Use Mole Ratios - Chemistry

1. Iron reacts with oxygen to form iron(III) oxide: $\textbf{4Fe} + \textbf{3O}_2 \rightarrow \textbf{2Fe}_2\textbf{O}_3$ If $6.0\ \text{mol}$ of $\text{Fe}$ react completely, how many moles of $\text{Fe}_2\text{O}_3$ form?
   Answer: $3.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation 4Fe + 3O₂ → 2Fe₂O₃, we're given 6.0 mol Fe and need to find moles of Fe₂O₃ formed. The mole ratio conversion factor is (2 moles Fe₂O₃ / 4 moles Fe) from the coefficients, so: 6.0 mol Fe × (2 mol Fe₂O₃ / 4 mol Fe) = 6.0 × (2/4) = 6.0 × (1/2) = 3.0 mol Fe₂O₃. Choice A correctly calculates 3.0 mol by applying the 2:4 (or 1:2) coefficient ratio as a conversion factor and performing accurate arithmetic. Common errors include using the wrong ratio or multiplying by 2 instead of dividing, which would give 12.0 mol. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification: 6.0 mol Fe produces 3.0 mol Fe₂O₃, giving ratio 6:3 = 2:1, matching the coefficient ratio 4:2 = 2:1 for Fe:Fe₂O₃ ✓.
2. For the balanced reaction: $\textbf{N}_2 + \textbf{3H}_2 \rightarrow \textbf{2NH}_3$ If $6.0\ \text{mol}$ of $\text{H}_2$ react completely, how many moles of $\text{NH}_3$ form?
   Answer: $4.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation N₂ + 3H₂ → 2NH₃, we're given 6.0 mol H₂ and need to find moles of NH₃. The mole ratio conversion factor is (2 moles NH₃ / 3 moles H₂) from the coefficients, so: 6.0 mol H₂ × (2 mol NH₃ / 3 mol H₂) = 6.0 × (2/3) = 4.0 mol NH₃. Choice B correctly calculates 4.0 mol by applying the 2:3 coefficient ratio as a conversion factor and performing accurate arithmetic. A common error would be inverting the ratio to get 9.0 mol or using the wrong coefficients to get 12.0 mol. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification: 6.0 mol H₂ produces 4.0 mol NH₃, giving ratio 6:4 = 3:2, which matches the coefficient ratio 3:2 for H₂:NH₃ ✓.
3. For the balanced reaction $\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3,$ if $6.0\ \text{mol}$ of $\text{H}_2$ react completely, how many moles of $\text{NH}_3$ form?
   Answer: $4.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation N₂ + 3H₂ → 2NH₃, we're given 6.0 mol H₂ and need to find moles of NH₃ produced. The conversion factor is (2 mol NH₃ / 3 mol H₂) from the coefficients, so: 6.0 mol H₂ × (2 mol NH₃ / 3 mol H₂) = 4.0 mol NH₃. Choice C correctly calculates 4.0 mol by applying the 2:3 coefficient ratio as a conversion factor and performing accurate arithmetic. Choice A (9.0 mol) incorrectly inverts and misapplies the ratio, while choice D (12.0 mol) incorrectly multiplies coefficients instead of using them as a ratio. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio - here 4:6 simplifies to 2:3, matching the NH₃:H₂ coefficient ratio of 2:3 ✓.
4. Hydrogen peroxide decomposes according to: $2 \text{H}_2 \text{O}_2 \rightarrow 2 \text{H}_2 \text{O} + \text{O}_2$ If $6.0\ \text{mol}$ of $\text{H}_2 \text{O}$ form, how many moles of $\text{O}_2$ form?
   Answer: $3.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For example, from $2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$, if given 5 moles of $\text{O}_2$ and asked to find moles of $\text{H}_2\text{O}$, the mole ratio conversion factor is $(2 \text{ moles } \text{H}_2\text{O} / 1 \text{ mole } \text{O}_2)$ from the coefficients, so 5 moles $\text{O}_2$ × $(2 \text{ moles } \text{H}_2\text{O} / 1 \text{ mole } \text{O}_2)$ = 10 moles $\text{H}_2\text{O}$. The "moles $\text{O}_2$" units cancel, leaving "moles $\text{H}_2\text{O}$"—dimensional analysis ensures you set up the fraction correctly! In this case, for $2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2$ with 6.0 mol $\text{H}_2\text{O}$ given and $\text{O}_2$ wanted, the conversion factor is $(1 \text{ mol } \text{O}_2 / 2 \text{ mol } \text{H}_2\text{O})$, so 6.0 mol $\text{H}_2\text{O}$ × $(1/2)$ = 3.0 mol $\text{O}_2$. Choice C correctly calculates moles by applying the appropriate coefficient ratio as a conversion factor and performing accurate arithmetic. Choice A might result from using $(2/1)$ instead of $(1/2)$, essentially inverting the ratio, but double-check by ensuring units cancel properly. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Example step-by-step: $\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3$. Given: 9 moles $\text{H}_2$. Find: moles $\text{NH}_3$. Coefficients: $\text{H}_2$ has 3, $\text{NH}_3$ has 2. Conversion factor: $(2 \text{ moles } \text{NH}_3 / 3 \text{ moles } \text{H}_2)$. Calculation: 9 moles $\text{H}_2$ × $(2/3)$ = 6 moles $\text{NH}_3$. Check: 9:6 simplifies to 3:2, matching coefficient ratio 3:2 for $\text{H}_2$: $\text{NH}_3$ ✓. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. If equation shows 2:1 ratio and you got 6 moles from 3 moles given, does 6:3 equal 2:1? Yes (both are 2:1), so answer likely correct! If equation shows 1:3 ratio and you got 9 moles from 3 moles, does 9:3 equal 1:3? No (9:3 = 3:1, not 1:3), so error occurred—probably inverted the ratio! This proportion check catches most mistakes and takes 3 seconds.
5. Consider the balanced equation: $\mathrm{2H_2 + O_2 \rightarrow 2H_2O}$ If $5.0\ \text{mol}$ of $\mathrm{H_2}$ react completely, how many moles of $\mathrm{H_2O}$ form?
   Answer: $5.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For example, from $2\mathrm{H_2 + O_2 \rightarrow 2H_2O}$, if given 5 moles of O2 and asked to find moles of H2O, the mole ratio conversion factor is (2\ \text{moles H_2O} / 1\ \text{mole O_2}) from the coefficients, so 5\ \text{moles O_2} \times (2\ \text{moles H_2O} / 1\ \text{mole O_2}) = 10\ \text{moles H_2O}. The "moles O2" units cancel, leaving "moles H2O"—dimensional analysis ensures you set up the fraction correctly! For this problem, with $2\mathrm{H_2 + O_2 \rightarrow 2H_2O}$ and 5.0 mol H2 given to find mol H2O, the conversion factor is (2\ \text{mol H_2O} / 2\ \text{mol H_2}), so 5.0\ \text{mol H_2} \times (2/2) = 5.0\ \text{mol H_2O}. Choice C correctly calculates moles by applying the appropriate coefficient ratio as a conversion factor and performing accurate arithmetic. A common distractor like choice A might result from mistakenly using a 1:2 ratio instead of 2:2, but remember to always use the exact coefficients—here it's 1:1 after simplifying, so keep practicing to avoid inversion errors. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) $\times$ (conversion factor) = answer in moles. Example step-by-step: $\mathrm{N_2 + 3H_2 \rightarrow 2NH_3}$. Given: 9 moles H2. Find: moles NH3. Coefficients: H2 has 3, NH3 has 2. Conversion factor: (2\ \text{moles NH_3} / 3\ \text{moles H_2}). Calculation: 9\ \text{moles H_2} \times (2/3) = 6\ \text{moles NH_3}. Check: 9:6 simplifies to 3:2, matching coefficient ratio 3:2 for H2:NH3 ✓. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. If equation shows 2:1 ratio and you got 6 moles from 3 moles given, does 6:3 equal 2:1? Yes (both are 2:1), so answer likely correct! If equation shows 1:3 ratio and you got 9 moles from 3 moles, does 9:3 equal 1:3? No (9:3 = 3:1, not 1:3), so error occurred—probably inverted the ratio! This proportion check catches most mistakes and takes 3 seconds.
6. Calcium carbonate decomposes as shown: $\mathrm{CaCO_3 \rightarrow CaO + CO_2}$ If $0.75 \text{ mol}$ of $\mathrm{CaCO_3}$ decompose completely, how many moles of $\mathrm{CO_2}$ are produced?
   Answer: $0.75 \text{ mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For example, from $2\mathrm{H_2} + \mathrm{O_2} \rightarrow 2\mathrm{H_2O}$, if given 5 moles of O2 and asked to find moles of H2O, the mole ratio conversion factor is $(2 \text{ moles H2O} / 1 \text{ mole O2})$ from the coefficients, so 5 moles O2 × $(2 \text{ moles H2O} / 1 \text{ mole O2}) = 10 \text{ moles H2O}$. The "moles O2" units cancel, leaving "moles H2O"—dimensional analysis ensures you set up the fraction correctly! For this problem, with $\mathrm{CaCO_3} \rightarrow \mathrm{CaO} + \mathrm{CO_2}$ and 0.75 mol CaCO3 given to find mol CO2, the conversion factor is $(1 \text{ mol CO2} / 1 \text{ mol CaCO3})$, so 0.75 mol CaCO3 × $(1/1) = 0.75 \text{ mol CO2}$. Choice A correctly calculates moles by applying the appropriate coefficient ratio as a conversion factor and performing accurate arithmetic. Choice D might come from misreading coefficients or adding extras, but it's a clean 1:1 ratio—you're on the right track! The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Example step-by-step: $\mathrm{N_2} + 3\mathrm{H_2} \rightarrow 2\mathrm{NH_3}$. Given: 9 moles H2. Find: moles NH3. Coefficients: H2 has 3, NH3 has 2. Conversion factor: $(2 \text{ moles NH3} / 3 \text{ moles H2})$. Calculation: 9 moles H2 × $(2/3) = 6 \text{ moles NH3}$. Check: 9:6 simplifies to 3:2, matching coefficient ratio 3:2 for H2:NH3 ✓. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. If equation shows 2:1 ratio and you got 6 moles from 3 moles given, does 6:3 equal 2:1? Yes (both are 2:1), so answer likely correct! If equation shows 1:3 ratio and you got 9 moles from 3 moles, does 9:3 equal 1:3? No (9:3 = 3:1, not 1:3), so error occurred—probably inverted the ratio! This proportion check catches most mistakes and takes 3 seconds.
7. Given the balanced equation: $\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}$ If $3.0$ mol of $\text{CH}_4$ burn completely, how many moles of $\text{O}_2$ are required?
   Answer: 6.0 mol $\text{O}_2$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation CH₄ + 2O₂ → CO₂ + 2H₂O, we're given 3.0 mol CH₄ and need to find moles of O₂ required. The mole ratio conversion factor is (2 moles O₂ / 1 mole CH₄) from the coefficients, so 3.0 mol CH₄ × (2 mol O₂ / 1 mol CH₄) = 6.0 mol O₂. Choice D correctly calculates 6.0 mol by applying the appropriate 2:1 coefficient ratio as a conversion factor and performing accurate arithmetic. Choice A (1.5 mol) incorrectly inverts the ratio and divides by 2, while Choice B (3.0 mol) incorrectly assumes a 1:1 ratio between CH₄ and O₂. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. Here, CH₄:O₂ has ratio 1:2, and our answer 3.0:6.0 simplifies to 1:2, confirming the answer is correct!
8. Hydrogen peroxide decomposes as shown: $2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2.$ If $7.0\ \text{mol}$ of $\text{H}_2\text{O}$ form, how many moles of $\text{O}_2$ form (assuming complete reaction)?
   Answer: $3.5\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation 2H₂O₂ → 2H₂O + O₂, we're given 7.0 mol H₂O formed and need to find moles of O₂ formed. The conversion factor is (1 mol O₂ / 2 mol H₂O) from the coefficients, so: 7.0 mol H₂O × (1 mol O₂ / 2 mol H₂O) = 3.5 mol O₂. Choice A correctly calculates 3.5 mol by applying the 1:2 coefficient ratio as a conversion factor and performing accurate arithmetic. Choice B (14.0 mol) incorrectly inverts the ratio and multiplies by 2, while choice C (7.0 mol) incorrectly assumes a 1:1 ratio between H₂O and O₂. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio - here 3.5:7 simplifies to 1:2, matching the O₂:H₂O coefficient ratio of 1:2 ✓.
9. Aluminum reacts with oxygen to form aluminum oxide: $\textbf{4Al} + \textbf{3O}_2 \rightarrow \textbf{2Al}_2\textbf{O}_3$ If $1.5\ \text{mol}$ of $\text{Al}_2\text{O}_3$ form, how many moles of $\text{Al}$ were consumed?
   Answer: $3.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation 4Al + 3O₂ → 2Al₂O₃, we're given 1.5 mol Al₂O₃ formed and need to find moles of Al consumed. The mole ratio conversion factor is (4 moles Al / 2 moles Al₂O₃) from the coefficients, so: 1.5 mol Al₂O₃ × (4 mol Al / 2 mol Al₂O₃) = 1.5 × (4/2) = 1.5 × 2 = 3.0 mol Al. Choice C correctly calculates 3.0 mol by applying the 4:2 (or 2:1) coefficient ratio as a conversion factor and performing accurate arithmetic. Common errors include using the inverted ratio to get 0.75 mol or using wrong coefficients. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification: 3.0 mol Al produces 1.5 mol Al₂O₃, giving ratio 3.0:1.5 = 2:1, matching the coefficient ratio 4:2 = 2:1 for Al:Al₂O₃ ✓.
10. Consider the balanced equation: $2Na + Cl_2 \rightarrow 2NaCl$ How many moles of $Na$ are required to react completely with $3.0\ \text{mol}$ of $Cl_2$?
    Answer: $6.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For example, from 2H2 + O2 → 2H2O, if given 5 moles of O2 and asked to find moles of H2O, the mole ratio conversion factor is (2 moles H2O / 1 mole O2) from the coefficients, so 5 moles O2 × (2 moles H2O / 1 mole O2) = 10 moles H2O. The "moles O2" units cancel, leaving "moles H2O"—dimensional analysis ensures you set up the fraction correctly! For this specific question, with the balanced equation 2Na + Cl2 → 2NaCl and 3.0 mol of Cl2 given, the conversion factor to find moles of Na required is (2 mol Na / 1 mol Cl2), so 3.0 mol Cl2 × (2/1) = 6.0 mol Na. Choice C correctly calculates the moles by applying the appropriate coefficient ratio as a conversion factor and performing accurate arithmetic. A common distractor like choice B (3.0 mol) might result from assuming a 1:1 ratio without checking coefficients, but always extract ratios directly from the equation. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Example step-by-step: N2 + 3H2 → 2NH3. Given: 9 moles H2. Find: moles NH3. Coefficients: H2 has 3, NH3 has 2. Conversion factor: (2 moles NH3 / 3 moles H2). Calculation: 9 moles H2 × (2/3) = 6 moles NH3. Check: 9:6 simplifies to 3:2, matching coefficient ratio 3:2 for H2:NH3 ✓. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. If equation shows 2:1 ratio and you got 6 moles from 3 moles given, does 6:3 equal 2:1? Yes (both are 2:1), so answer likely correct! If equation shows 1:3 ratio and you got 9 moles from 3 moles, does 9:3 equal 1:3? No (9:3 = 3:1, not 1:3), so error occurred—probably inverted the ratio! This proportion check catches most mistakes and takes 3 seconds.
11. Methane burns according to: $\textbf{CH}_4 + \textbf{2O}_2 \rightarrow \textbf{CO}_2 + \textbf{2H}_2\textbf{O}$ If $3.5\ \text{mol}$ of $\text{CH}_4$ react completely, how many moles of $\text{O}_2$ are required?
    Answer: $7.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation CH₄ + 2O₂ → CO₂ + 2H₂O, we're given 3.5 mol CH₄ and need to find moles of O₂ required. The mole ratio conversion factor is (2 moles O₂ / 1 mole CH₄) from the coefficients, so: 3.5 mol CH₄ × (2 mol O₂ / 1 mol CH₄) = 7.0 mol O₂. Choice D correctly calculates 7.0 mol by applying the 2:1 coefficient ratio as a conversion factor and performing accurate arithmetic. Common errors include using the wrong ratio or dividing instead of multiplying, which would give 1.75 mol instead of 7.0 mol. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification: 3.5 mol CH₄ requires 7.0 mol O₂, giving ratio 3.5:7.0 = 1:2, matching the coefficient ratio 1:2 for CH₄:O₂ ✓.
12. Photosynthesis can be represented by $\mathrm{6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2}$ If a plant uses $12\ \text{mol}$ of $\mathrm{CO_2}$, how many moles of $\mathrm{O_2}$ are produced (assume enough water is available)?
    Answer: $12\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For example, from $2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$, if given 5 moles of O2 and asked to find moles of H2O, the mole ratio conversion factor is $(2\ \text{moles H}_2\text{O} / 1\ \text{mole O}_2)$ from the coefficients, so $5\ \text{moles O}_2 \times (2\ \text{moles H}_2\text{O} / 1\ \text{mole O}_2) = 10\ \text{moles H}_2\text{O}$. The "moles O2" units cancel, leaving "moles H2O"—dimensional analysis ensures you set up the fraction correctly! For this problem, with $6\mathrm{CO_2} + 6\mathrm{H_2O} \rightarrow \mathrm{C_6H_{12}O_6} + 6\mathrm{O_2}$ and 12 mol CO2 given to find mol O2, the conversion factor is $(6\ \text{mol O}_2 / 6\ \text{mol CO}_2)$, so $12\ \text{mol CO}_2 \times (6/6) = 12\ \text{mol O}_2$. Choice D correctly calculates moles by applying the appropriate coefficient ratio as a conversion factor and performing accurate arithmetic. Choice B might arise from confusing with other ratios or arithmetic errors, but since it's 1:1 simplified, it's direct—keep practicing these larger coefficients! The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Example step-by-step: $N_2 + 3H_2 \rightarrow 2NH_3$. Given: 9 moles H2. Find: moles NH3. Coefficients: H2 has 3, NH3 has 2. Conversion factor: $(2\ \text{moles NH}_3 / 3\ \text{moles H}_2)$. Calculation: $9\ \text{moles H}_2 \times (2/3) = 6\ \text{moles NH}_3$. Check: 9:6 simplifies to 3:2, matching coefficient ratio 3:2 for H2:NH3 ✓. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. If equation shows 2:1 ratio and you got 6 moles from 3 moles given, does 6:3 equal 2:1? Yes (both are 2:1), so answer likely correct! If equation shows 1:3 ratio and you got 9 moles from 3 moles, does 9:3 equal 1:3? No (9:3 = 3:1, not 1:3), so error occurred—probably inverted the ratio! This proportion check catches most mistakes and takes 3 seconds.
13. Consider the balanced equation: $2H_2O_2 \rightarrow 2H_2O + O_2$ If $6.0 \text{ mol}$ of $H_2O$ form, how many moles of $O_2$ form?
    Answer: $3.0 \text{ mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For example, from $2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$, if given 5 moles of $\text{O}_2$ and asked to find moles of $\text{H}_2\text{O}$, the mole ratio conversion factor is $(2 \text{ moles } \text{H}_2\text{O} / 1 \text{ mole } \text{O}_2)$ from the coefficients, so 5 moles $\text{O}_2$ × $(2 \text{ moles } \text{H}_2\text{O} / 1 \text{ mole } \text{O}_2)$ = 10 moles $\text{H}_2\text{O}$. The "moles $\text{O}_2$" units cancel, leaving "moles $\text{H}_2\text{O}$"—dimensional analysis ensures you set up the fraction correctly! For this specific question, with the balanced equation $2\text{H}_2\text{O}_2 \rightarrow 2\text{H}_2\text{O} + \text{O}_2$ and 6.0 mol of $\text{H}_2\text{O}$ formed, the conversion factor to find moles of $\text{O}_2$ formed is $(1 \text{ mol } \text{O}_2 / 2 \text{ mol } \text{H}_2\text{O})$, so 6.0 mol $\text{H}_2\text{O}$ × $(1/2)$ = 3.0 mol $\text{O}_2$. Choice B correctly calculates the moles by applying the appropriate coefficient ratio as a conversion factor and performing accurate arithmetic. A common distractor like choice A (12.0 mol) might result from inverting the ratio to $(2/1)$ or confusing the products, but ensure the wanted substance is in the numerator. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Example step-by-step: $\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3$. Given: 9 moles $\text{H}_2$. Find: moles $\text{NH}_3$. Coefficients: $\text{H}_2$ has 3, $\text{NH}_3$ has 2. Conversion factor: $(2 \text{ moles } \text{NH}_3 / 3 \text{ moles } \text{H}_2)$. Calculation: 9 moles $\text{H}_2$ × $(2/3)$ = 6 moles $\text{NH}_3$. Check: 9:6 simplifies to 3:2, matching coefficient ratio 3:2 for $\text{H}_2$: $\text{NH}_3$ ✓. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. If equation shows 2:1 ratio and you got 6 moles from 3 moles given, does 6:3 equal 2:1? Yes (both are 2:1), so answer likely correct! If equation shows 1:3 ratio and you got 9 moles from 3 moles, does 9:3 equal 1:3? No (9:3 = 3:1, not 1:3), so error occurred—probably inverted the ratio! This proportion check catches most mistakes and takes 3 seconds.
14. Consider the balanced equation: $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$ If a plant uses $12 \text{ mol}$ of $CO_2$ in photosynthesis, how many moles of $O_2$ are produced (assuming enough $H_2O$ is available)?
    Answer: $12 \text{ mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For example, from $2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$, if given 5 moles of $\text{O}_2$ and asked to find moles of $\text{H}_2\text{O}$, the mole ratio conversion factor is $(2 \text{ moles } \text{H}_2\text{O} / 1 \text{ mole } \text{O}_2)$ from the coefficients, so $5 \text{ moles } \text{O}_2 \times (2 \text{ moles } \text{H}_2\text{O} / 1 \text{ mole } \text{O}_2) = 10 \text{ moles } \text{H}_2\text{O}$. The "moles $\text{O}_2$" units cancel, leaving "moles $\text{H}_2\text{O}$"—dimensional analysis ensures you set up the fraction correctly! For this specific question, with the balanced equation $6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$ and 12 mol of $\text{CO}_2$ given, the conversion factor to find moles of $\text{O}_2$ is $(6 \text{ mol } \text{O}_2 / 6 \text{ mol } \text{CO}_2)$, so $12 \text{ mol } \text{CO}_2 \times (6/6) = 12 \text{ mol } \text{O}_2$. Choice D correctly calculates the moles by applying the appropriate coefficient ratio as a conversion factor and performing accurate arithmetic. A common distractor like choice B (72 mol) might result from multiplying coefficients unnecessarily, like 6×12, but stick to the ratio and given moles only. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Example step-by-step: $\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3$. Given: 9 moles $\text{H}_2$. Find: moles $\text{NH}_3$. Coefficients: $\text{H}_2$ has 3, $\text{NH}_3$ has 2. Conversion factor: $(2 \text{ moles } \text{NH}_3 / 3 \text{ moles } \text{H}_2)$. Calculation: $9 \text{ moles } \text{H}_2 \times (2/3) = 6 \text{ moles } \text{NH}_3$. Check: 9:6 simplifies to 3:2, matching coefficient ratio 3:2 for $\text{H}_2$: $\text{NH}_3$ ✓. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. If equation shows 2:1 ratio and you got 6 moles from 3 moles given, does 6:3 equal 2:1? Yes (both are 2:1), so answer likely correct! If equation shows 1:3 ratio and you got 9 moles from 3 moles, does 9:3 equal 1:3? No (9:3 = 3:1, not 1:3), so error occurred—probably inverted the ratio! This proportion check catches most mistakes and takes 3 seconds.
15. Calcium carbonate decomposes according to: $\text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2$ If $2.5\ \text{mol}$ of $\text{CaCO}_3$ decompose completely, how many moles of $\text{CO}_2$ are produced?
    Answer: $2.5\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For example, from 2H2 + O2 → 2H2O, if given 5 moles of O2 and asked to find moles of H2O, the mole ratio conversion factor is (2 moles H2O / 1 mole O2) from the coefficients, so 5 moles O2 × (2 moles H2O / 1 mole O2) = 10 moles H2O. The "moles O2" units cancel, leaving "moles H2O"—dimensional analysis ensures you set up the fraction correctly! In this case, for CaCO3 → CaO + CO2 with 2.5 mol CaCO3 given and CO2 wanted, the conversion factor is (1 mol CO2 / 1 mol CaCO3), so 2.5 mol CaCO3 × (1/1) = 2.5 mol CO2. Choice A correctly calculates moles by applying the appropriate coefficient ratio as a conversion factor and performing accurate arithmetic. Choice B might result from dividing by 2 unnecessarily, but note the 1:1 ratio means they are equal. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Example step-by-step: N2 + 3H2 → 2NH3. Given: 9 moles H2. Find: moles NH3. Coefficients: H2 has 3, NH3 has 2. Conversion factor: (2 moles NH3 / 3 moles H2). Calculation: 9 moles H2 × (2/3) = 6 moles NH3. Check: 9:6 simplifies to 3:2, matching coefficient ratio 3:2 for H2:NH3 ✓. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. If equation shows 2:1 ratio and you got 6 moles from 3 moles given, does 6:3 equal 2:1? Yes (both are 2:1), so answer likely correct! If equation shows 1:3 ratio and you got 9 moles from 3 moles, does 9:3 equal 1:3? No (9:3 = 3:1, not 1:3), so error occurred—probably inverted the ratio! This proportion check catches most mistakes and takes 3 seconds.
16. Calcium carbonate decomposes according to: $\textbf{CaCO}_3 \rightarrow \textbf{CaO} + \textbf{CO}_2$ If $2.25\ \text{mol}$ of $\text{CaCO}_3$ decompose completely, how many moles of $\text{CO}_2$ are produced?
    Answer: $2.25\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation CaCO₃ → CaO + CO₂, we're given 2.25 mol CaCO₃ and need to find moles of CO₂ produced. The mole ratio conversion factor is (1 mole CO₂ / 1 mole CaCO₃) from the coefficients, so: 2.25 mol CaCO₃ × (1 mol CO₂ / 1 mol CaCO₃) = 2.25 mol CO₂. Choice B correctly calculates 2.25 mol by applying the 1:1 coefficient ratio as a conversion factor - when the ratio is 1:1, the number of moles stays the same! Common errors include doubling or halving the amount unnecessarily. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification: 2.25 mol CaCO₃ produces 2.25 mol CO₂, giving ratio 2.25:2.25 = 1:1, matching the coefficient ratio 1:1 for CaCO₃:CO₂ ✓.
17. Sulfur dioxide reacts with oxygen to form sulfur trioxide: $2\text{SO}_2 + \text{O}_2 \rightarrow 2\text{SO}_3.$ If $3.0\ \text{mol}$ of $\text{SO}_2$ react completely, how many moles of $\text{O}_2$ are required?
    Answer: $1.5\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation 2SO₂ + O₂ → 2SO₃, we're given 3.0 mol SO₂ and need to find moles of O₂ required. The conversion factor is (1 mol O₂ / 2 mol SO₂) from the coefficients, so: 3.0 mol SO₂ × (1 mol O₂ / 2 mol SO₂) = 1.5 mol O₂. Choice B correctly calculates 1.5 mol by applying the 1:2 coefficient ratio as a conversion factor and performing accurate arithmetic. Choice A (6.0 mol) incorrectly inverts the ratio and multiplies, while choice C (3.0 mol) incorrectly assumes a 1:1 ratio between SO₂ and O₂. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio - here 1.5:3 simplifies to 1:2, matching the O₂:SO₂ coefficient ratio of 1:2 ✓.
18. Sulfuric acid neutralizes sodium hydroxide as shown: $\text{H}_2\text{SO}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}$ If $3.0\ \text{mol}$ of $\text{H}_2\text{SO}_4$ react completely, how many moles of $\text{NaOH}$ are required?
    Answer: $6.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For example, from $2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$, if given $5$ moles of $\text{O}_2$ and asked to find moles of $\text{H}_2\text{O}$, the mole ratio conversion factor is $(2 \text{ moles } \text{H}_2\text{O} / 1 \text{ mole } \text{O}_2)$ from the coefficients, so $5 \text{ moles } \text{O}_2 \times (2 \text{ moles } \text{H}_2\text{O} / 1 \text{ mole } \text{O}_2) = 10 \text{ moles } \text{H}_2\text{O}$. The "moles O2" units cancel, leaving "moles H2O"—dimensional analysis ensures you set up the fraction correctly! In this case, for $\text{H}_2\text{SO}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}$ with $3.0 \text{ mol } \text{H}_2\text{SO}_4$ given and $\text{NaOH}$ wanted, the conversion factor is $(2 \text{ mol } \text{NaOH} / 1 \text{ mol } \text{H}_2\text{SO}_4)$, so $3.0 \text{ mol } \text{H}_2\text{SO}_4 \times (2/1) = 6.0 \text{ mol } \text{NaOH}$. Choice D correctly calculates moles by applying the appropriate coefficient ratio as a conversion factor and performing accurate arithmetic. Choice A might result from halving instead of multiplying by 2, but confirm the ratio by checking the balanced equation. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Example step-by-step: $\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3$. Given: $9$ moles $\text{H}_2$. Find: moles $\text{NH}_3$. Coefficients: $\text{H}_2$ has 3, $\text{NH}_3$ has 2. Conversion factor: $(2 \text{ moles } \text{NH}_3 / 3 \text{ moles } \text{H}_2)$. Calculation: $9 \text{ moles } \text{H}_2 \times (2/3) = 6 \text{ moles } \text{NH}_3$. Check: 9:6 simplifies to 3:2, matching coefficient ratio 3:2 for $\text{H}_2$: $\text{NH}_3$ ✓. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio. If equation shows 2:1 ratio and you got 6 moles from 3 moles given, does 6:3 equal 2:1? Yes (both are 2:1), so answer likely correct! If equation shows 1:3 ratio and you got 9 moles from 3 moles, does 9:3 equal 1:3? No (9:3 = 3:1, not 1:3), so error occurred—probably inverted the ratio! This proportion check catches most mistakes and takes 3 seconds.
19. Methane burns according to the balanced equation $\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}.$ If $3.0\ \text{mol}$ of $\text{CH}_4$ react completely, how many moles of $\text{CO}_2$ are produced?
    Answer: $3.0\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation CH₄ + 2O₂ → CO₂ + 2H₂O, we're given 3.0 mol CH₄ and need to find moles of CO₂ produced. The conversion factor is (1 mol CO₂ / 1 mol CH₄) from the coefficients, so: 3.0 mol CH₄ × (1 mol CO₂ / 1 mol CH₄) = 3.0 mol CO₂. Choice C correctly calculates 3.0 mol by applying the 1:1 coefficient ratio as a conversion factor and performing accurate arithmetic. Choice B (6.0 mol) incorrectly uses the oxygen coefficient of 2, while choice A (1.5 mol) incorrectly inverts a ratio that shouldn't be inverted for a 1:1 relationship. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification trick: after calculating, check if your answer maintains the coefficient ratio - here 3:3 equals 1:1, matching the CO₂:CH₄ coefficient ratio of 1:1 ✓.
20. Sulfur burns in oxygen to form sulfur dioxide: $\textbf{S} + \textbf{O}_2 \rightarrow \textbf{SO}_2$ If $4.8\ \text{mol}$ of $\text{SO}_2$ are produced, how many moles of $\text{O}_2$ were required (assuming complete reaction)?
    Answer: $4.8\ \text{mol}$ This question tests your ability to use mole ratios from balanced equations as conversion factors to calculate how many moles of one substance react with or form from a given number of moles of another substance. Using mole ratios for stoichiometry calculations follows a simple pattern: from the balanced equation, create a conversion factor (fraction) using coefficients where the numerator is the coefficient of the substance you want to find and the denominator is the coefficient of the substance you're given, then multiply the given number of moles by this conversion factor. For the equation S + O₂ → SO₂, we're given 4.8 mol SO₂ produced and need to find moles of O₂ required. The mole ratio conversion factor is (1 mole O₂ / 1 mole SO₂) from the coefficients, so: 4.8 mol SO₂ × (1 mol O₂ / 1 mol SO₂) = 4.8 mol O₂. Choice B correctly calculates 4.8 mol by applying the 1:1 coefficient ratio as a conversion factor - when all coefficients are 1, the moles are equal! Common errors include halving to get 2.4 mol or doubling to get 9.6 mol. The mole ratio calculation recipe: (1) Write the balanced equation and identify the given substance and wanted substance. (2) Read their coefficients from the equation. (3) Set up conversion factor as fraction: (coefficient of wanted substance / coefficient of given substance). Put what you want on top, what you have on bottom! (4) Multiply: (given moles) × (conversion factor) = answer in moles. Quick verification: 4.8 mol O₂ produces 4.8 mol SO₂, giving ratio 4.8:4.8 = 1:1, matching the coefficient ratio 1:1 for O₂:SO₂ ✓.

Start this quiz