Q: A student mixes 17.0 mL of $7.50 \times 10^{-4}\ \text{M}$ crystal violet (CV) solution and 3.00 mL of $0.30\ \text{M}$ NaOH solution. What is the initial $[OH^-]$ concentration after mixing?

$4.29 \times 10^{-2}\ \text{M}$

Q: A calibration curve for FeSCN$^{2+}$ is given by $y = 5521x + 0.043$, where $y$ is absorbance and $x$ is concentration in M. If a sample has an absorbance of 0.187, what is the FeSCN$^{2+}$ concentration?

$2.61 \times 10^{-3}\ \text{M}$

Q: A student is preparing a standard solution of FeSCN$^{2+}$ by mixing $10.0\ \text{mL}$ of $0.00100\ \text{M}$ Fe(NO$_3$)$_3$ and $10.0\ \text{mL}$ of $0.00200\ \text{M}$ KSCN$. What is the final FeSCN$^{2+}$ concentration at equilibrium, assuming all SCN$^-$ is converted?

$5.21 \times 10^{-4}\ \text{M}$

Q: A student is preparing a buffer solution using acetic acid and sodium acetate. Which equation should be used to calculate the pH of the buffer?

$\text{pH} = pK_a + \log \frac{[A^-]}{[HA]}$

Question 1

A kinetics experiment for the reaction $N_2(g) + 3Cl_2(g) ightarrow 2NCl_3(g)$ yields the following initial rates:
Trial I: $[N_2] = 0.200\ 	ext{M}$, $[Cl_2] = 0.300\ 	ext{M}$, rate $= 0.0100\ 	ext{M/min}$
Trial II: $[N_2] = 0.200\ 	ext{M}$, $[Cl_2] = 0.600\ 	ext{M}$, rate $= 0.0200\ 	ext{M/min}$
Trial III: $[N_2] = 0.400\ 	ext{M}$, $[Cl_2] = 0.300\ 	ext{M}$, rate $= 0.0200\ 	ext{M/min}$
What is the correct rate law for this reaction?

Accepted Answer

$	ext{rate} = k[N_2][Cl_2]$

Question 2

A student mixes 17.0 mL of $7.50 	imes 10^{-4}\ 	ext{M}$ crystal violet (CV) solution and 3.00 mL of $0.30\ 	ext{M}$ NaOH solution. What is the initial $[OH^-]$ concentration after mixing?

Accepted Answer

$4.29 	imes 10^{-2}\ 	ext{M}$

Question 3

A calibration curve for FeSCN$^{2+}$ is given by $y = 5521x + 0.043$, where $y$ is absorbance and $x$ is concentration in M. If a sample has an absorbance of 0.187, what is the FeSCN$^{2+}$ concentration?

Accepted Answer

$2.61 	imes 10^{-3}\ 	ext{M}$

Question 4

A $0.250\ 	ext{M}$ solution of a weak acid is $1.25\%$ dissociated. What is the percent ionization of this acid?

Accepted Answer

$1.25\%$

Question 5

A $0.250\ 	ext{M}$ solution of a weak base has a pH of $11.28$. What is the $K_b$ of this base?

Accepted Answer

$3.5 	imes 10^{-3}$

Question 6

A $0.585\ 	ext{g}$ sample of toilet cleaner is titrated with $0.1327\ 	ext{M}$ NaOH. The titration curve shows an equivalence point at $16.34\ 	ext{mL}$ of NaOH. How many moles of HCl are in the sample?

Accepted Answer

$2.17 	imes 10^{-3}$ mol

Question 7

A $0.585\ 	ext{g}$ sample of toilet cleaner is titrated with $0.1327\ 	ext{M}$ NaOH. The titration curve shows an equivalence point at $16.34\ 	ext{mL}$ of NaOH. What is the percent by mass of HCl in the sample? (Molar mass of HCl = $36.46\ 	ext{g/mol}$)

Accepted Answer

$13.6\%$

Question 8

A student is preparing a standard solution of FeSCN$^{2+}$ by mixing $10.0\ 	ext{mL}$ of $0.00100\ 	ext{M}$ Fe(NO$_3$)$_3$ and $10.0\ 	ext{mL}$ of $0.00200\ 	ext{M}$ KSCN$. What is the final FeSCN$^{2+}$ concentration at equilibrium, assuming all SCN$^-$ is converted?

Accepted Answer

$5.21 	imes 10^{-4}\ 	ext{M}$

Question 9

A $20.00\ 	ext{mL}$ sample of $0.1234\ 	ext{M}$ monoprotic weak acid is titrated with NaOH of unknown concentration. The equivalence point is reached at $24.00\ 	ext{mL}$ of NaOH. What is the concentration of the NaOH solution?

Accepted Answer

$0.1027\ 	ext{M}$

Question 10

A $20.00\ 	ext{mL}$ sample of $0.1234\ 	ext{M}$ monoprotic weak acid is titrated with NaOH. The initial pH of the acid is $3.17$. What is the $K_a$ of this weak acid?

Accepted Answer

$1.8 	imes 10^{-4}$

Question 11

A solution is prepared by mixing $16.0\ 	ext{mL}$ of $0.025\ 	ext{M}$ Cu(NO$_3$)$_2$ and $16.0\ 	ext{mL}$ of $0.015\ 	ext{M}$ KIO$_3$. The solution is heated until saturated, then cooled. The equilibrium concentration of Cu(IO$_3$)$_2$ is $1.7 	imes 10^{-4}\ 	ext{M}$. What is the experimental $K_{sp}$ of Cu(IO$_3$)$_2$?

Accepted Answer

$5.3 	imes 10^{-7}$

Question 12

Which of the following best describes the effect of increasing the wavelength of light used in a colorimeter when measuring the absorbance of a blue solution?

Accepted Answer

Absorbance will decrease as the wavelength moves away from the absorption maximum.

Question 13

A student is analyzing the kinetics of a reaction and finds that doubling the concentration of reactant Z doubles the rate, while doubling the concentration of reactant Y has no effect. What is the order of the reaction with respect to Z and Y?

Accepted Answer

First order in Z, zero order in Y

Question 14

A student is preparing to work in the chemistry lab. Which of the following is NOT an appropriate safety practice?

Accepted Answer

Wearing sandals or flip-flops

Question 15

A solution is prepared by mixing $10.0\ 	ext{mL}$ of $0.00100\ 	ext{M}$ Fe(NO$_3$)$_3$ and $10.0\ 	ext{mL}$ of $0.00200\ 	ext{M}$ KSCN. What is the limiting reagent?

Accepted Answer

Fe(NO$_3$)$_3$

Question 16

A student is asked to calculate the pH of a $0.250\ 	ext{M}$ solution of a weak acid that is $1.25\%$ dissociated. What is the correct pH?

Accepted Answer

$2.52$

Question 17

A student is analyzing a reaction and finds that the rate law is $	ext{rate} = k[OH^-][CV]$. If $[OH^-]$ is doubled and $[CV]$ is halved, what happens to the rate?

Accepted Answer

The rate remains the same

Question 18

A student is using a spectrophotometer to measure the concentration of a colored solution. Which of the following best describes the relationship between absorbance (A), molar absorptivity ($\epsilon$), path length (l), and concentration (c)?

Accepted Answer

$A = \epsilon l c$

Question 19

A student is analyzing the titration curve of a weak acid with a strong base. At the half-equivalence point, what is the relationship between pH and $pK_a$?

Accepted Answer

$	ext{pH} = pK_a$

Question 20

A student is preparing a buffer solution using acetic acid and sodium acetate. Which equation should be used to calculate the pH of the buffer?

Accepted Answer

$	ext{pH} = pK_a + \log \frac{[A^-]}{[HA]}$

General Chemistry Exam Study Guide: Chemical Kinetics, Equilibrium, Acid-Base Chemistry, and Laboratory Calculations

Study Guide - Practice Questions

Study Guide - Flashcards