AP Chemistry Flashcards: Concentration Changes Over Time

What this deck covers

This deck focuses on Concentration Changes Over Time, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.

How to use these flashcards

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: What is the half-life formula for a second-order reaction?

Answer: $t_{1/2} = \frac{1}{k[\text{A}]_0}$. Half-life inversely proportional to initial concentration.

Flashcard 2: What is the effect of a catalyst on the rate of reaction?

Answer: Increases the reaction rate. Lowers activation energy without being consumed.

Flashcard 3: What does the slope of a second-order reaction plot $\frac{1}{[\text{A}]}$ vs. time represent?

Answer: Rate constant $k$. Slope of reciprocal concentration vs time plot.

Flashcard 4: Identify the graph shape for a first-order reaction concentration vs. time plot.

Answer: Exponential decay curve. Rate proportional to concentration creates exponential decay.

Flashcard 5: How do you determine the reaction order from a concentration vs. time graph?

Answer: Analyze the shape of the plot. Different orders produce characteristic curve shapes.

Flashcard 6: How do you determine the reaction order from a concentration vs. time graph?

Answer: Analyze the shape of the plot. Different orders produce characteristic curve shapes.

Flashcard 7: What is the half-life formula for a first-order reaction?

Answer: $t_{1/2} = \frac{\ln(2)}{k}$. Constant half-life independent of initial concentration.

Flashcard 8: Which order of reaction has a constant half-life regardless of initial concentration?

Answer: First-order reaction. Constant half-life is characteristic of first-order kinetics.

Flashcard 9: Determine the reaction order: Rate is independent of $[\text{A}]$ concentration.

Answer: Zero-order reaction. Rate independent of concentration changes.

Flashcard 10: Which factor does NOT affect the rate constant $k$?

Answer: Concentration of reactants. Rate constant depends only on temperature and catalyst.

Flashcard 11: What is the half-life formula for a second-order reaction?

Answer: $t_{1/2} = \frac{1}{k[\text{A}]_0}$. Half-life inversely proportional to initial concentration.

Flashcard 12: What is the rate law expression for a reaction $aA + bB \rightarrow cC$?

Answer: $\text{rate} = k[A]^m[B]^n$. Rate depends on concentrations raised to their respective orders.

Flashcard 13: State the integrated rate law for a first-order reaction.

Answer: $[\text{A}]_t = [\text{A}]_0 e^{-kt}$. Exponential decay relationship for first-order kinetics.

Flashcard 14: What does the slope of a second-order reaction plot $\frac{1}{[\text{A}]}$ vs. time represent?

Answer: Rate constant $k$. Slope of reciprocal concentration vs time plot.

Flashcard 15: Identify the graph shape for a first-order reaction concentration vs. time plot.

Answer: Exponential decay curve. Rate proportional to concentration creates exponential decay.

Flashcard 16: Identify the graph shape for a second-order reaction concentration vs. time plot.

Answer: Inversely proportional curve. Rate proportional to concentration squared.

Flashcard 17: Identify the units of the rate constant $k$ for a second-order reaction.

Answer: Units: $\text{M}^{-1} \text{s}^{-1}$. Second-order rate constant has units of reciprocal concentration-time.

Flashcard 18: Determine the reaction order: Rate is independent of $[\text{A}]$ concentration.

Answer: Zero-order reaction. Rate independent of concentration changes.

Flashcard 19: Which order of reaction has a constant half-life regardless of initial concentration?

Answer: First-order reaction. Constant half-life is characteristic of first-order kinetics.

Flashcard 20: State the integrated rate law for a zero-order reaction.

Answer: $[\text{A}]_t = [\text{A}]_0 - kt$. Linear decrease with time for zero-order kinetics.

Flashcard 21: What is the role of the frequency factor $A$ in the Arrhenius equation?

Answer: Represents collision frequency factor. Pre-exponential factor in Arrhenius equation.

Flashcard 22: Identify the units of the rate constant $k$ for a first-order reaction.

Answer: Units: $\text{s}^{-1}$. First-order rate constant has units of reciprocal time.

Flashcard 23: State the Arrhenius equation.

Answer: $k = A e^{-\frac{E_a}{RT}}$. Exponential relationship between rate constant and temperature.

Flashcard 24: Identify the graph shape for a second-order reaction concentration vs. time plot.

Answer: Inversely proportional curve. Rate proportional to concentration squared.

Flashcard 25: How does the concentration of reactants change over time in a second-order reaction?

Answer: Decreases more steeply than first-order. Rate proportional to concentration squared.

Flashcard 26: State the integrated rate law for a zero-order reaction.

Answer: $[\text{A}]_t = [\text{A}]_0 - kt$. Linear decrease with time for zero-order kinetics.

Flashcard 27: What is the effect of concentration on the rate for a zero-order reaction?

Answer: Rate is independent of concentration. Rate remains constant regardless of concentration.

Flashcard 28: Which factor does NOT affect the rate constant $k$?

Answer: Concentration of reactants. Rate constant depends only on temperature and catalyst.

Flashcard 29: What is the effect of a catalyst on activation energy $E_a$?

Answer: Decreases activation energy $E_a$. Provides alternative pathway with lower energy barrier.

Flashcard 30: State the integrated rate law for a zero-order reaction.

Answer: $[\text{A}]_t = [\text{A}]_0 - kt$. Linear decrease with time for zero-order kinetics.

Flashcard 31: How does the concentration of reactants change over time in a first-order reaction?

Answer: Decreases exponentially. Rate proportional to remaining concentration.

Flashcard 32: What is the relationship between reaction rate and concentration for a first-order reaction?

Answer: Rate is directly proportional to concentration. Rate equals rate constant times concentration.

Flashcard 33: What is the relationship between reaction rate and concentration for a first-order reaction?

Answer: Rate is directly proportional to concentration. Rate equals rate constant times concentration.

Flashcard 34: Which order of reaction has a constant half-life regardless of initial concentration?

Answer: First-order reaction. Constant half-life is characteristic of first-order kinetics.

Flashcard 35: What is the effect of a catalyst on the overall reaction rate?

Answer: Increases overall reaction rate. Provides faster pathway without changing equilibrium.

Flashcard 36: What is the effect of a catalyst on the overall reaction rate?

Answer: Increases overall reaction rate. Provides faster pathway without changing equilibrium.

Flashcard 37: Identify the units of the rate constant $k$ for a first-order reaction.

Answer: Units: $\text{s}^{-1}$. First-order rate constant has units of reciprocal time.

Flashcard 38: State the integrated rate law for a zero-order reaction.

Answer: $[\text{A}]_t = [\text{A}]_0 - kt$. Linear decrease with time for zero-order kinetics.

Flashcard 39: What is the effect of a catalyst on the overall reaction rate?

Answer: Increases overall reaction rate. Provides faster pathway without changing equilibrium.

Flashcard 40: Calculate the rate if $k = 0.5 \text{s}^{-1}$ and $[\text{A}] = 2 \text{M}$ for a first-order reaction.

Answer: Rate = $1 \text{M} \text{s}^{-1}$. Rate equals $k$ times concentration for first-order.

Flashcard 41: Determine the reaction order: Doubling $[\text{A}]$ quadruples the reaction rate.

Answer: Second-order reaction. Rate proportional to concentration squared.

Flashcard 42: Identify the units of the rate constant $k$ for a second-order reaction.

Answer: Units: $\text{M}^{-1} \text{s}^{-1}$. Second-order rate constant has units of reciprocal concentration-time.

Flashcard 43: What is the relationship between reaction rate and concentration for a first-order reaction?

Answer: Rate is directly proportional to concentration. Rate equals rate constant times concentration.

Flashcard 44: Calculate the rate if $k = 0.5 \text{s}^{-1}$ and $[\text{A}] = 2 \text{M}$ for a first-order reaction.

Answer: Rate = $1 \text{M} \text{s}^{-1}$. Rate equals $k$ times concentration for first-order.

Flashcard 45: What is the effect of a catalyst on activation energy $E_a$?

Answer: Decreases activation energy $E_a$. Provides alternative pathway with lower energy barrier.

Flashcard 46: Identify the graph shape for a zero-order reaction concentration vs. time plot.

Answer: Straight line downward. Constant rate produces linear concentration decrease.

Flashcard 47: Determine the reaction order: $[\text{A}]$ halves every 20 seconds regardless of initial concentration.

Answer: First-order reaction. Constant half-life indicates first-order kinetics.

Flashcard 48: Determine the reaction order: Doubling $[\text{A}]$ quadruples the reaction rate.

Answer: Second-order reaction. Rate proportional to concentration squared.

Flashcard 49: How does the concentration of reactants change over time in a second-order reaction?

Answer: Decreases more steeply than first-order. Rate proportional to concentration squared.

Flashcard 50: How is the rate constant $k$ affected by temperature increase?

Answer: The rate constant $k$ increases. Higher temperature provides more kinetic energy for reactions.

Flashcard 51: What is the half-life formula for a zero-order reaction?

Answer: $t_{1/2} = \frac{ { [ \text{A} ] } _0 }{2k}$. Half-life depends on initial concentration for zero-order.

Flashcard 52: How does temperature affect reaction rate?

Answer: Higher temperature increases reaction rate. More molecular collisions occur at higher temperatures.

Flashcard 53: Identify the units of the rate constant $k$ for a zero-order reaction.

Answer: Units: $\text{M} \text{s}^{-1}$. Zero-order reactions have rate units of concentration per time.

Flashcard 54: How does the concentration of reactants change over time in a first-order reaction?

Answer: Decreases exponentially. Rate proportional to remaining concentration.

Flashcard 55: How is the rate constant $k$ affected by temperature increase?

Answer: The rate constant $k$ increases. Higher temperature provides more kinetic energy for reactions.

Flashcard 56: Identify the units of the rate constant $k$ for a first-order reaction.

Answer: Units: $\text{s}^{-1}$. First-order rate constant has units of reciprocal time.

Flashcard 57: Identify the units of the rate constant $k$ for a zero-order reaction.

Answer: Units: $\text{M} \text{s}^{-1}$. Zero-order reactions have rate units of concentration per time.

Flashcard 58: What is the half-life formula for a zero-order reaction?

Answer: $t_{1/2} = \frac{[\text{A}]_0}{2k}$. Half-life depends on initial concentration for zero-order.

Flashcard 59: What is the effect of concentration on the rate for a zero-order reaction?

Answer: Rate is independent of concentration. Rate remains constant regardless of concentration.

Flashcard 60: Calculate the half-life if $k = 0.693 \text{s}^{-1}$ for a first-order reaction.

Answer: $t_{1/2} = 1 \text{s}$. Using $t_{1/2} = \frac{\ln(2)}{k}$ formula.

Flashcard 61: State the integrated rate law for a second-order reaction.

Answer: $\frac{1}{[\text{A}]_t} = \frac{1}{[\text{A}]_0} + kt$. Reciprocal concentration increases linearly with time.

Flashcard 62: How does the concentration of reactants change over time in a second-order reaction?

Answer: Decreases more steeply than first-order. Rate proportional to concentration squared.

Flashcard 63: How does temperature affect reaction rate?

Answer: Higher temperature increases reaction rate. More molecular collisions occur at higher temperatures.

Flashcard 64: Identify the graph shape for a zero-order reaction concentration vs. time plot.

Answer: Straight line downward. Constant rate produces linear concentration decrease.

Flashcard 65: Determine the reaction order: $[\text{A}]$ halves every 20 seconds regardless of initial concentration.

Answer: First-order reaction. Constant half-life indicates first-order kinetics.

Flashcard 66: State the Arrhenius equation.

Answer: $k = A e^{-\frac{E_a}{RT}}$. Exponential relationship between rate constant and temperature.

Flashcard 67: Calculate the half-life if $k = 0.693 \text{s}^{-1}$ for a first-order reaction.

Answer: $t_{1/2} = 1 \text{s}$. Using $t_{1/2} = \frac{\ln(2)}{k}$ formula.

Flashcard 68: Calculate the half-life if $k = 0.693 \text{s}^{-1}$ for a first-order reaction.

Answer: $t_{1/2} = 1 \text{s}$. Using $t_{1/2} = \frac{\ln(2)}{k}$ formula.

Flashcard 69: What is the Arrhenius equation used for?

Answer: Calculating the temperature dependence of the rate constant. Relates rate constant to temperature and activation energy.

Flashcard 70: How do you determine the reaction order from a concentration vs. time graph?

Answer: Analyze the shape of the plot. Different orders produce characteristic curve shapes.

Flashcard 71: What is the half-life formula for a zero-order reaction?

Answer: $t_{1/2} = \frac{[\text{A}]_0}{2k}$. Half-life depends on initial concentration for zero-order.

Flashcard 72: What is the rate law expression for a reaction $aA + bB \rightarrow cC$?

Answer: $\text{rate} = k[A]^m[B]^n$. Rate depends on concentrations raised to their respective orders.

Flashcard 73: What does the slope of a first-order reaction plot $[\text{ln[A]}]$ vs. time represent?

Answer: Negative rate constant $-k$. Slope of $\ln[A]$ vs time plot.

Flashcard 74: Calculate the rate if $k = 0.5 \text{s}^{-1}$ and $[\text{A}] = 2 \text{M}$ for a first-order reaction.

Answer: Rate = $1 \text{M} \text{s}^{-1}$. Rate equals $k$ times concentration for first-order.

Flashcard 75: How does the concentration of reactants change over time in a second-order reaction?

Answer: Decreases more steeply than first-order. Rate proportional to concentration squared.

Flashcard 76: How does temperature affect reaction rate?

Answer: Higher temperature increases reaction rate. More molecular collisions occur at higher temperatures.

Flashcard 77: What is the half-life formula for a zero-order reaction?

Answer: $t_{1/2} = \frac{[\text{A}]_0}{2k}$. Half-life depends on initial concentration for zero-order.

Flashcard 78: How is the rate constant $k$ affected by temperature increase?

Answer: The rate constant $k$ increases. Higher temperature provides more kinetic energy for reactions.

Flashcard 79: Determine the reaction order: $[\text{A}]$ halves every 20 seconds regardless of initial concentration.

Answer: First-order reaction. Constant half-life indicates first-order kinetics.

Flashcard 80: What is the role of the frequency factor $A$ in the Arrhenius equation?

Answer: Represents collision frequency factor. Pre-exponential factor in Arrhenius equation.

Flashcard 81: What is the role of the frequency factor $A$ in the Arrhenius equation?

Answer: Represents collision frequency factor. Pre-exponential factor in Arrhenius equation.

Flashcard 82: Which factor does NOT affect the rate constant $k$?

Answer: Concentration of reactants. Rate constant depends only on temperature and catalyst.

Flashcard 83: Determine the reaction order: Rate is independent of $[\text{A}]$ concentration.

Answer: Zero-order reaction. Rate independent of concentration changes.

Flashcard 84: Identify the graph shape for a zero-order reaction concentration vs. time plot.

Answer: Straight line downward. Constant rate produces linear concentration decrease.

Flashcard 85: Identify the units of the rate constant $k$ for a second-order reaction.

Answer: Units: $\text{M}^{-1} \text{s}^{-1}$. Second-order rate constant has units of reciprocal concentration-time.

Flashcard 86: State the Arrhenius equation.

Answer: $k = A e^{-\frac{E_a}{RT}}$. Exponential relationship between rate constant and temperature.

Flashcard 87: What does the slope of a second-order reaction plot $\frac{1}{[\text{A}]}$ vs. time represent?

Answer: Rate constant $k$. Slope of reciprocal concentration vs time plot.

Flashcard 88: Which order of reaction has a constant half-life regardless of initial concentration?

Answer: First-order reaction. Constant half-life is characteristic of first-order kinetics.

Flashcard 89: Determine the reaction order: Doubling $[\text{A}]$ quadruples the reaction rate.

Answer: Second-order reaction. Rate proportional to concentration squared.

Flashcard 90: What does the slope of a first-order reaction plot $[\text{ln[A]}]$ vs. time represent?

Answer: Negative rate constant $-k$. Slope of $\ln[A]$ vs time plot.

Flashcard 91: Identify the units of the rate constant $k$ for a zero-order reaction.

Answer: Units: $\text{M} \text{s}^{-1}$. Zero-order reactions have rate units of concentration per time.

Flashcard 92: How does the concentration of reactants change over time in a first-order reaction?

Answer: Decreases exponentially. Rate proportional to remaining concentration.

Flashcard 93: How does the concentration of reactants change over time in a first-order reaction?

Answer: Decreases exponentially. Rate proportional to remaining concentration.

Flashcard 94: What is the half-life formula for a second-order reaction?

Answer: $t_{1/2} = \frac{1}{k[\text{A}]_0}$. Half-life inversely proportional to initial concentration.

Flashcard 95: What happens to the concentration of reactants over time in a zero-order reaction?

Answer: Decreases linearly over time. Constant rate independent of remaining concentration.

Flashcard 96: What is the rate law expression for a reaction $aA + bB \rightarrow cC$?

Answer: $\text{rate} = k[A]^m[B]^n$. Rate depends on concentrations raised to their respective orders.