IB Chemistry Quiz: Understand Amount Of Chemical Change

In the thermite reaction, 10.8 g of aluminium is reacted with 30.0 g of iron(III) oxide. The equation for the reaction is: $\text{2Al(s) + Fe}_2\text{O}_3\text{(s)} \rightarrow \text{Al}_2\text{O}_3\text{(s) + 2Fe(l)}$. What is the maximum mass of iron that can be produced? ($A_r$: Al = 26.98, Fe = 55.85, O = 16.00)

A 12.5 g sample of impure limestone is heated strongly, causing the calcium carbonate within it to decompose. After the reaction, 5.50 g of calcium oxide is collected. $\text{CaCO}_3\text{(s)} \rightarrow \text{CaO(s) + CO}_2\text{(g)}$. If the limestone sample is known to be 92.0% CaCO₃ by mass, what is the percentage yield of calcium oxide? ($M_r$: CaCO₃ = 100.09, CaO = 56.08)

The decomposition of sodium azide, NaN₃, is used in some automobile airbags. $\text{2NaN}_3\text{(s)} \rightarrow \text{2Na(s) + 3N}_2\text{(g)}$. What volume of nitrogen gas, in dm³, is produced from the decomposition of 13.0 g of NaN₃ if the gas is collected at 25 °C and 101 kPa? ($M_r$: NaN₃ = 65.02; R = 8.31 J K⁻¹ mol⁻¹)

Which type of reaction is most likely to have a theoretical atom economy of 100%?

Titanium is extracted from its ore (TiO₂) in a two-step process: Step 1: $\text{TiO}_2 + \text{2C} + \text{2Cl}_2 \rightarrow \text{TiCl}_4 + \text{2CO}$ (90% yield) Step 2: $\text{TiCl}_4 + \text{2Mg} \rightarrow \text{Ti} + \text{2MgCl}_2$ (95% yield)

What is the minimum mass of TiO₂ required to produce 100.0 g of pure titanium, assuming the yields are as stated? ($A_r$: Ti = 47.87, O = 16.00)

100 cm³ of 0.20 mol dm⁻³ barium chloride solution is mixed with 100 cm³ of 0.10 mol dm⁻³ aluminium sulfate solution, forming a precipitate of barium sulfate. $\text{3BaCl}_2\text{(aq) + Al}_2\text{(SO}_4\text{)}_3\text{(aq)} \rightarrow \text{3BaSO}_4\text{(s) + 2AlCl}_3\text{(aq)}$. What is the final concentration of chloride ions, [Cl⁻], in the solution, assuming the volumes are additive?

A piece of zinc metal of mass 6.54 g is added to 150 cm³ of 0.500 mol dm⁻³ silver nitrate solution. The reaction that occurs is: $\text{Zn(s) + 2AgNO}_3\text{(aq)} \rightarrow \text{Zn(NO}_3\text{)}_2\text{(aq) + 2Ag(s)}$. Which statement is correct? ($A_r$: Zn = 65.38, Ag = 107.87)

A 4.58 g sample of a mixture of sodium chloride (NaCl) and anhydrous sodium carbonate (Na₂CO₃) was dissolved in water and made up to 250.0 cm³. A 25.00 cm³ aliquot of this solution required 22.80 cm³ of 0.150 mol dm⁻³ HCl for complete reaction with the carbonate. What is the percentage by mass of Na₂CO₃ in the original mixture? ($M_r$: Na₂CO₃ = 105.99)

Equal volumes of all gases at the same temperature and pressure contain equal numbers of particles. Consider the reaction: $\text{N}_2\text{(g) + 3H}_2\text{(g)} \rightarrow \text{2NH}_3\text{(g)}$. If 20 cm³ of nitrogen is reacted with 40 cm³ of hydrogen under constant conditions, what is the total volume of gas remaining in the container?

Given the reaction $\text{2SO}_2\text{(g) + O}_2\text{(g)} \rightarrow \text{2SO}_3\text{(g)}$, what is the theoretical yield of SO₃, if the reaction starts with 50.0 g of SO₂ and 50.0 g of O₂? ($M_r$: SO₂ = 64.07, O₂ = 32.00, SO₃ = 80.07)

In the Ostwald process for producing nitric acid, ammonia is oxidized: $\text{4NH}_3\text{(g) + 5O}_2\text{(g)} \rightarrow \text{4NO(g) + 6H}_2\text{O(g)}$. If 10.0 g of NH₃ is reacted with 20.0 g of O₂, what mass of the excess reactant remains after the reaction is complete? ($M_r$: NH₃ = 17.03, O₂ = 32.00)

Which of the following would result in an experimentally determined percentage yield greater than 100% for the precipitation of a solid product?

When hydrated copper(II) sulfate, CuSO₄·5H₂O, is heated, it decomposes: $\text{CuSO}_4\cdot\text{5H}_2\text{O(s)} \rightarrow \text{CuSO}_4\text{(s) + 5H}_2\text{O(g)}$. A student heats 10.0 g of the hydrated salt and collects 5.80 g of anhydrous copper(II) sulfate. What is the percentage yield for this reaction? ($M_r$: CuSO₄·5H₂O = 249.72, CuSO₄ = 159.62)

A 2.50 g sample of impure calcium carbonate was added to 50.0 cm³ of 1.00 mol dm⁻³ hydrochloric acid, which was in excess. Once the reaction finished, the unreacted acid was titrated with 0.500 mol dm⁻³ sodium hydroxide solution, and 16.5 cm³ was required for neutralization. Reaction 1: $\text{CaCO}_3\text{(s) + 2HCl(aq)} \rightarrow \text{CaCl}_2\text{(aq) + H}_2\text{O(l) + CO}_2\text{(g)}$ Reaction 2: $\text{HCl(aq) + NaOH(aq)} \rightarrow \text{NaCl(aq) + H}_2\text{O(l)}$

What is the percentage purity of the calcium carbonate sample? ($M_r$: CaCO₃ = 100.09)

Methanol can be produced by two different processes. Process 1: $\text{CO(g) + 2H}_2\text{(g)} \rightarrow \text{CH}_3\text{OH(l)}$ Process 2: $\text{CO}_2\text{(g) + 3H}_2\text{(g)} \rightarrow \text{CH}_3\text{OH(l) + H}_2\text{O(l)}$ Which statement correctly compares the atom economy of the two processes for producing methanol?

A student aims to prepare 12.8 g of copper by reacting excess zinc with copper(II) sulfate solution. $\text{Zn(s) + CuSO}_4\text{(aq)} \rightarrow \text{ZnSO}_4\text{(aq) + Cu(s)}$. After collecting and drying the product, the student finds the actual mass of copper to be 11.5 g. Which statement correctly identifies a possible reason for the percentage yield being less than 100% and a way to improve it?

When 2.40 g of magnesium ribbon is completely burned in oxygen, the mass of magnesium oxide produced is 3.98 g. If the same amount of magnesium were burned in a limited oxygen supply where only 75% of the magnesium reacts, what mass of unreacted magnesium would remain?

When 4.80 g of $\text{CaCO}_3$ is heated, it decomposes according to: $\text{CaCO}_3(s) \rightarrow \text{CaO}(s) + \text{CO}_2(g)$. If the reaction goes to 85% completion, what volume of $\text{CO}_2$ gas is produced at STP?

A hydrated salt has the formula $\text{MgSO}_4 \cdot x\text{H}_2\text{O}$. When 2.466 g of the hydrated salt is heated to remove all water, 1.204 g of anhydrous $\text{MgSO}_4$ remains. Determine the value of x and the percentage of water in the original hydrated salt.

A student performs a titration using 25.00 mL of 0.1050 M $\text{NaOH}$ to neutralize 30.00 mL of $\text{HCl}$ solution. If the student accidentally reads the burette incorrectly and records the volume as 24.50 mL instead of 25.00 mL, what is the percent error in the calculated concentration of the $\text{HCl}$?