Q: Which equation correctly relates molarity, moles of solute, and volume of solution?

$M = \frac{\text{moles of solute}}{\text{volume of solution in liters}}$

Q: How many grams of NaF are present in 75 mL of a 0.4 M NaF solution? (Molar mass of NaF = 42 g/mol)

$\text{moles} = 0.075 \times 0.4 = 0.03$ mol; $0.03 \times 42 = 1.26$ g

Q: A 20.0 mL sample of 2.00 M HCl is diluted with 15.5 mL of water. What is the new concentration?

$M_{\text{dilute}} = \frac{2.00 \times 20.0}{20.0 + 15.5} = 1.22$ M

Q: How many mL of 4.0 M AgNO$_3$ are needed to make 320 mL of 0.2 M AgNO$_3$?

$V_{\text{conc}} = \frac{0.2 \times 320}{4.0} = 16$ mL

Q: A titration is performed using 48.0 mL of NaOH to neutralize 35.0 mL of 0.144 M H$_2$SO$_4$. What is the molarity of the NaOH solution?

$M_{\text{NaOH}} = \frac{1.01 \times 10^{-2}}{0.048} = 0.21$ M

Q: How many grams of NaOH are needed to neutralize 20 mL of 0.150 M H$_2$SO$_4$? (Molar mass of NaOH = 40 g/mol)

$\text{moles H}_2\text{SO}_4 = 0.02 \times 0.150 = 0.003$ mol; $\text{moles NaOH} = 0.003 \times 2 = 0.006$ mol; $0.006 \times 40 = 0.24$ g

Question 1

A student prepares a solution by dissolving 8.4 g of KCl (molar mass = 74.5 g/mol) in enough water to make 500 mL of solution. What is the molarity of the KCl solution?

Accepted Answer

$\frac{8.4}{74.5} = 0.113$ mol; $\frac{0.113}{0.5} = 0.226$ M

Question 2

Which equation correctly relates molarity, moles of solute, and volume of solution?

Accepted Answer

$M = \frac{	ext{moles of solute}}{	ext{volume of solution in liters}}$

Question 3

How many grams of NaF are present in 75 mL of a 0.4 M NaF solution? (Molar mass of NaF = 42 g/mol)

Accepted Answer

$	ext{moles} = 0.075 	imes 0.4 = 0.03$ mol; $0.03 	imes 42 = 1.26$ g

Question 4

A 1.0 M solution of Na$_2$SO$_4$ contains what concentration of Na$^+$ ions?

Accepted Answer

$2.0$ M

Question 5

What volume of 0.5 M NaF solution is needed to obtain 0.01 mol of NaF?

Accepted Answer

$V = \frac{0.01}{0.5} = 0.02$ L = $20$ mL

Question 6

A 20.0 mL sample of 2.00 M HCl is diluted with 15.5 mL of water. What is the new concentration?

Accepted Answer

$M_{	ext{dilute}} = \frac{2.00 	imes 20.0}{20.0 + 15.5} = 1.22$ M

Question 7

How many mL of 4.0 M AgNO$_3$ are needed to make 320 mL of 0.2 M AgNO$_3$?

Accepted Answer

$V_{	ext{conc}} = \frac{0.2 	imes 320}{4.0} = 16$ mL

Question 8

Which statement about dilution is correct?

Accepted Answer

The number of moles of solute remains the same before and after dilution.

Question 9

A titration is performed using 48.0 mL of NaOH to neutralize 35.0 mL of 0.144 M H$_2$SO$_4$. What is the molarity of the NaOH solution?

Accepted Answer

$M_{	ext{NaOH}} = \frac{1.01 	imes 10^{-2}}{0.048} = 0.21$ M

Question 10

In a titration, what is the equivalence point?

Accepted Answer

The point at which stoichiometrically equivalent quantities of reactants are mixed.

Question 11

How many grams of NaOH are needed to neutralize 20 mL of 0.150 M H$_2$SO$_4$? (Molar mass of NaOH = 40 g/mol)

Accepted Answer

$	ext{moles H}_2	ext{SO}_4 = 0.02 	imes 0.150 = 0.003$ mol; $	ext{moles NaOH} = 0.003 	imes 2 = 0.006$ mol; $0.006 	imes 40 = 0.24$ g

Question 12

Which of the following best describes the process of titration?

Accepted Answer

A solution of known concentration is added to a solution of unknown concentration until the reaction is complete.

Question 13

If 20.2 mL of 0.1 M Ag$^+$ is needed to react with all the Cl$^-$ in a sample, how many grams of Cl$^-$ are present? (Molar mass of Cl$^-$ = 35.5 g/mol)

Accepted Answer

$	ext{moles Ag}^+ = 0.0202 	imes 0.1 = 0.00202$ mol; $0.00202 	imes 35.5 = 0.0717$ g

Question 14

Which step is necessary when solving a solution stoichiometry problem involving grams and molarity?

Accepted Answer

Convert grams to moles using molar mass before using molarity.

Question 15

A solution is prepared by diluting 10 mL of 3.0 M HNO$_3$ to a final volume of 100 mL. What is the final concentration?

Accepted Answer

$M_{	ext{dilute}} = \frac{3.0 	imes 10}{100} = 0.3$ M

Question 16

Which of the following is NOT a type of reaction commonly used in titrations?

Accepted Answer

Combustion reaction

Question 17

If you have a 1.0 M solution of CaCl$_2$, what is the concentration of Cl$^-$ ions?

Accepted Answer

$2.0$ M

Question 18

Which formula is used to calculate the volume of solution needed for dilution?

Accepted Answer

$M_{	ext{conc}} 	imes V_{	ext{conc}} = M_{	ext{dilute}} 	imes V_{	ext{dilute}}$

Chapter 4: Reactions in Aqueous Solutions – Concentration, Dilution, and Titration

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