AP Chemistry Flashcards: Deviation From Ideal Gas Law

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This deck focuses on Deviation From Ideal Gas Law, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.

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Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: Identify a gas that behaves nearly ideally under ordinary conditions.

Answer: Helium. Small, light atoms with weak intermolecular forces.

Flashcard 2: Find the pressure correction in Van der Waals equation for $1 \text{mol}$ of gas.

Answer: $\frac{a}{V^2}$. For 1 mole, $n = 1$, so the correction becomes $\frac{a}{V^2}$.

Flashcard 3: What is the Van der Waals equation?

Answer: $(P + \frac{an^2}{V^2})(V - nb) = nRT$. Modified ideal gas law accounting for real gas behavior.

Flashcard 4: What does a high value of 'a' indicate in Van der Waals equation?

Answer: Strong intermolecular forces. Large 'a' means strong attractive forces between molecules.

Flashcard 5: Provide the value of the universal gas constant 'R'.

Answer: $R = 0.0821 \frac{L \times atm}{mol \times K}$. The standard value used in gas law calculations.

Flashcard 6: How does Van der Waals equation modify the Ideal Gas Law?

Answer: Corrects for volume and pressure deviations. Adds corrections for molecular size and intermolecular forces.

Flashcard 7: State the definition of an ideal gas.

Answer: An ideal gas perfectly follows the Ideal Gas Law. A theoretical gas that obeys all gas law assumptions perfectly.

Flashcard 8: What is the primary cause of deviation at low temperatures?

Answer: Increased intermolecular attractions. Lower temperatures enhance attractive forces between gas molecules.

Flashcard 9: Name another condition for deviation from ideal behavior.

Answer: Low temperature. Reduces kinetic energy, allowing intermolecular forces to dominate.

Flashcard 10: What is the Ideal Gas Law equation?

Answer: $PV = nRT$. The fundamental relationship between pressure, volume, moles, and temperature.

Flashcard 11: What is the primary focus of the Van der Waals equation?

Answer: Correcting Ideal Gas Law for real gases. Modifies ideal gas law to account for real gas behavior.

Flashcard 12: What is the significance of 'R' in the Ideal Gas Law?

Answer: 'R' is the universal gas constant. A proportionality constant linking pressure, volume, moles, and temperature.

Flashcard 13: Calculate pressure deviation using $P = 4 \text{atm}$, $a = 0.8$, $V = 20 \text{L}$.

Answer: $\text{Deviation} = \frac{0.8}{20^2}$. Pressure correction term: $\frac{a}{V^2}$ for 1 mole of gas.

Flashcard 14: What does 'a' in Van der Waals equation account for?

Answer: Intermolecular attraction forces. Parameter representing strength of intermolecular attractive forces.

Flashcard 15: Identify another assumption of the Ideal Gas Law.

Answer: Gas particles exert no intermolecular forces. Assumes no attractive or repulsive forces between particles.

Flashcard 16: What is the effect of molecular size on gas deviation?

Answer: Larger size increases deviation. Larger molecules occupy more space, increasing deviation from ideality.

Flashcard 17: Identify a situation where Ideal Gas Law fails.

Answer: At very high pressures. Extreme pressure makes particle volume and forces significant.

Flashcard 18: What is the effect of intermolecular forces on gas pressure?

Answer: Decreases observed pressure. Attractive forces reduce pressure exerted on container walls.

Flashcard 19: What does the term $nb$ in Van der Waals equation represent?

Answer: Volume occupied by gas particles. Total volume excluded due to finite molecular size.

Flashcard 20: What is the main limitation of the Ideal Gas Law?

Answer: Assumes no volume and no interactions between particles. Ignores real effects: molecular size and intermolecular forces.

Flashcard 21: Name a condition under which real gases deviate from ideal behavior.

Answer: High pressure. Forces particles closer, making volume and intermolecular forces significant.

Flashcard 22: Calculate $n$ if $P = 3 \text{atm}$, $V = 10 \text{L}$, $T = 400 \text{K}$, $R = 0.0821$.

Answer: $n = \frac{PV}{RT} = 0.914 \text{mol}$. Using $n = \frac{PV}{RT}$ with given values yields 0.914 mol.

Flashcard 23: What effect does increasing pressure have on gas behavior?

Answer: Gases deviate more from ideal behavior. Higher pressure compresses gas, making particle volume more significant.

Flashcard 24: Calculate corrected pressure using $P = 3 \text{atm}$, $a = 0.5$, $V = 10 \text{L}$.

Answer: $P' = 3 + \frac{0.5}{10^2} = 3.005 \text{atm}$. Adding pressure correction: $P + \frac{an^2}{V^2}$ for $n=1$.

Flashcard 25: What correction does $b$ account for in the Van der Waals equation?

Answer: Volume of gas particles. The finite size of gas molecules reduces available volume.

Flashcard 26: Calculate $T$ if $P = 2 \text{atm}$, $V = 5 \text{L}$, $n = 1 \text{mol}$, $R = 0.0821$.

Answer: $T = \frac{PV}{nR} = 121.95 \text{K}$. Rearranging ideal gas law: $T = \frac{PV}{nR}$ gives 121.95 K.

Flashcard 27: Identify the correction factor for intermolecular forces in Van der Waals.

Answer: $\frac{an^2}{V^2}$. Accounts for attractive forces reducing observed pressure.

Flashcard 28: Calculate $P$ if $V = 10 \text{L}$, $n = 1 \text{mol}$, $T = 300 \text{K}$, $R = 0.0821$.

Answer: $P = \frac{nRT}{V} = 2.463 \text{atm}$. Using $P = \frac{nRT}{V}$ with given values yields 2.463 atm.

Flashcard 29: Which gas law relates pressure and volume at constant temperature?

Answer: Boyle's Law. States that $PV$ is constant at fixed temperature.

Flashcard 30: What happens to $PV/nRT$ for an ideal gas?

Answer: Equals 1. Compressibility factor equals 1 for perfect ideal behavior.

Flashcard 31: Name one assumption of the Ideal Gas Law.

Answer: Gas particles have no volume. Assumes particles are point masses with negligible size.

Flashcard 32: What modification do real gases have compared to ideal gases?

Answer: Non-zero volume and intermolecular forces. Real gases have finite size and experience intermolecular attractions.

Flashcard 33: Which real gas behavior is corrected by the term $(P + \frac{an^2}{V^2})$?

Answer: Pressure correction for intermolecular forces. Accounts for reduced pressure due to intermolecular attractions.

Flashcard 34: Identify the term for the effective volume in Van der Waals equation.

Answer: $V - nb$. Available volume after subtracting space occupied by gas particles.

Flashcard 35: What effect does increasing pressure have on gas behavior?

Answer: Gases deviate more from ideal behavior. Higher pressure compresses gas, making particle volume more significant.

Flashcard 36: What happens to gas particles at low temperatures?

Answer: Intermolecular forces become significant. Reduced kinetic energy allows attractive forces to affect behavior.

Flashcard 37: Which gas law relates volume and temperature at constant pressure?

Answer: Charles's Law. States that $V/T$ is constant at fixed pressure.

Flashcard 38: State the critical temperature's influence on gas behavior.

Answer: Above it, gases behave more ideally. Higher temperatures overcome intermolecular forces, approaching ideal behavior.

Flashcard 39: Calculate volume if $P = 1 \text{atm}$, $n = 1 \text{mol}$, $T = 273 \text{K}$, $R = 0.0821$.

Answer: $V = \frac{nRT}{P} = 22.414 \text{L}$. Standard molar volume calculation at STP conditions.

Flashcard 40: What causes real gases to deviate from ideal behavior at high pressures?

Answer: Finite volume of gas particles. Molecular volume becomes significant fraction of container volume.