Q: A solution is prepared by dissolving $$0.75$$ mol of NaCl in $$500 mL of $$water. What is the molarity of the solution?

$$M = \frac{0.75}{0.500} = 1.5\ \text{M}$$

Q: A hospital pharmacist needs to prepare $$250 mL of a$$ $$1.0 M $$KCl solution from a $$4.0 M $$stock solution. What volume of the stock solution should be used?

$$M_1V_1 = M_2V_2$$; $$V_1$$ = \frac{1.0 \times 0.250}{4.0} = 0.0625\ \text{L} = 62.5\ \text{mL}$$

Q: If the $$[H^+] in a $$solution is $$1 \times 10$$^{-8}$$ M, what is the pH of the solution?

$$pH = -\log(1 \times 10$$^{-8}$$) = 8$$

Q: A student mixes $$50 mL of$$ $$6.0 M $$HCl with $$150 mL of $$water. What is the final concentration of HCl after dilution?

$$M_2$$ = \frac{6.0 \times 0.050}{0.200} = 1.5\ \text{M}$$

Q: A laboratory titration uses $$0.100 L of$$ $$0.50 M $$NaOH to neutralize $$0.050 L of $$HCl. What is the concentration of the HCl?

$$M_1V_1 = M_2V_2$$; $$M_1$$ = \frac{0.50 \times 0.100}{0.050} = 1.0\ \text{M}$$

Question 1

Which of the following best describes a double replacement reaction, and which is a correct example?

Accepted Answer

Ions in two compounds exchange partners; e.g., $$AgNO_3 + $$NaCl \rightarrow AgCl + $$NaNO_3$$

Question 2

A student is asked to balance the following equation: $$C_2H_6 + O_2$ \rightarrow CO_2$ + H_2O. $$Which of the following is the correct balanced equation?

Accepted Answer

$$2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O$$

Question 3

A solution is prepared by dissolving $$0.75$$ mol of NaCl in $$500 mL of $$water. What is the molarity of the solution?

Accepted Answer

$$M = \frac{0.75}{0.500} = 1.5\ 	ext{M}$$

Question 4

Which of the following statements about electrolytes is correct?

Accepted Answer

Nonelectrolytes produce no ions in solution, like sugar.

Question 5

A hospital pharmacist needs to prepare $$250 mL of a$$ $$1.0 M $$KCl solution from a $$4.0 M $$stock solution. What volume of the stock solution should be used?

Accepted Answer

$$M_1V_1 = M_2V_2$$; $$V_1$$ = \frac{1.0 	imes 0.250}{4.0} = 0.0625\ 	ext{L} = 62.5\ 	ext{mL}$$

Question 6

Which of the following best explains why the carbonate buffer system is critical in human blood?

Accepted Answer

It maintains blood pH by resisting changes when acids or bases are added.

Question 7

If the $$[H^+] in a $$solution is $$1 	imes 10$$^{-8}$$ M, what is the pH of the solution?

Accepted Answer

$$pH = -\log(1 	imes 10$$^{-8}$$) = 8$$

Question 8

Which of the following is a strong acid and will fully dissociate in water?

Accepted Answer

HNO$$_3$$

Question 9

A student mixes $$50 mL of$$ $$6.0 M $$HCl with $$150 mL of $$water. What is the final concentration of HCl after dilution?

Accepted Answer

$$M_2$$ = \frac{6.0 	imes 0.050}{0.200} = 1.5\ 	ext{M}$$

Question 10

Which of the following best describes a buffer solution?

Accepted Answer

A solution that resists changes in pH, typically made from a weak acid and its conjugate base.

Question 11

A laboratory titration uses $$0.100 L of$$ $$0.50 M $$NaOH to neutralize $$0.050 L of $$HCl. What is the concentration of the HCl?

Accepted Answer

$$M_1V_1 = M_2V_2$$; $$M_1$$ = \frac{0.50 	imes 0.100}{0.050} = 1.0\ 	ext{M}$$

Question 12

Which of the following is true about the conservation of mass in chemical reactions?

Accepted Answer

The number and type of atoms are the same before and after the reaction.

Question 13

Which of the following is an example of an endothermic reaction?

Accepted Answer

A reaction that absorbs heat from the surroundings, such as photosynthesis.

Question 14

A solution has a pH of $$4. $$What is the $$[H^+]$$ concentration?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$\ 	ext{M}$$

Question 15

Which of the following best describes the relationship between pH and pOH in aqueous solutions at $$25^\circC$$?

Accepted Answer

$$pH + pOH = 14$$

Question 16

Which of the following is a correct identification of an acid and a base according to the Brønsted-Lowry definition?

Accepted Answer

Acid: HCl (donates $$H^+$$); Base: NaOH (accepts $$H^+)$$

Question 17

A solution is described as saturated. What does this mean?

Accepted Answer

It contains undissolved solute and cannot dissolve more at that temperature.

Question 18

Which of the following best explains why ionic compounds like NaCl dissolve in water?

Accepted Answer

Water is polar and stabilizes the ions, allowing them to separate.

Question 19

A student is given $$100 mL of$$ $$0.20 M $$HNO$$_3$$ and asked to dilute it to $$0.050 M. $$What will be the final volume after dilution?

Accepted Answer

$$V_2$$ = \frac{0.20 	imes 0.100}{0.050} = 0.40\ 	ext{L} = 400\ 	ext{mL}$$

Question 20

Which of the following is a correct application of the 'like dissolves like' rule?

Accepted Answer

Ionic and polar solutes dissolve best in polar solvents like water.

CHE 107 Exam Study Guide: Chemical Reactions, Solutions, and Acids/Bases (Ch. 9–11)

Guida di studio - Domande di pratica

Study guide - Flashcard