Q: A student needs to prepare 250.0 mL of a 0.200 M NaCl solution from a 1.00 M NaCl stock solution. What volume of the stock solution should be used?

$$V_1$$ = \frac{M_2V_2}{$$M_1$$} = \frac{0.200 \times 250.0}{1.00} = 50.0\ \mathrm{mL}$$

Q: A 25.0 mL sample of 0.100 M $$\mathrm{H_2SO_4} is $$completely neutralized by 50.0 mL of $$\mathrm{NaOH}$$ solution. What is the concentration of the $$\mathrm{NaOH}$$ solution?

$$0.100\ \mathrm{M} \times \frac{25.0\ \mathrm{mL} \times 2}{50.0\ \mathrm{mL}} = 0.100\ \mathrm{M}$$

Q: A reaction has a theoretical yield of 12.0 g, but only 9.0 g of product is actually obtained. What is the percent yield?

$$\mathrm{Percent\ yield = \frac{9.0\ g}{12.0\ g} \times 100\% = 75\%}$$

Question 1

Which of the following correctly represents the balanced molecular equation for the reaction between aqueous sodium sulfate and barium chloride, and what is the precipitate formed?

Accepted Answer

$$\mathrm{Na_2SO_4(aq) + $$BaCl_2$$(aq) \rightarrow 2NaCl(aq) + $$BaSO_4$$(s)}$$; the precipitate is $$\mathrm{$$BaSO_4$$}.$$

Question 2

A student needs to prepare 250.0 mL of a 0.200 M NaCl solution from a 1.00 M NaCl stock solution. What volume of the stock solution should be used?

Accepted Answer

$$V_1$$ = \frac{M_2V_2}{$$M_1$$} = \frac{0.200 	imes 250.0}{1.00} = 50.0\ \mathrm{mL}$$

Question 3

Which of the following compounds is a strong electrolyte when dissolved in water?

Accepted Answer

$$\mathrm{$$NaNO_3$$}$$

Question 4

Which of the following is the correct net ionic equation for the neutralization of hydrochloric acid with sodium hydroxide?

Accepted Answer

$$\mathrm{H^+(aq) + OH^-(aq) \rightarrow H_2O(l)}$$

Question 5

Which of the following is the correct empirical formula for a compound containing 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 6

Which of the following is NOT a diatomic element in its natural state?

Accepted Answer

Sulfur ($$\mathrm{S_8$})$$

Question 7

A 25.0 mL sample of 0.100 M $$\mathrm{H_2SO_4} is $$completely neutralized by 50.0 mL of $$\mathrm{NaOH}$$ solution. What is the concentration of the $$\mathrm{NaOH}$$ solution?

Accepted Answer

$$0.100\ \mathrm{M} 	imes \frac{25.0\ \mathrm{mL} 	imes 2}{50.0\ \mathrm{mL}} = 0.100\ \mathrm{M}$$

Question 8

Which of the following is the correct name for $$\mathrm{Fe_2$(SO_4$)_3}$$?

Accepted Answer

Iron(III) sulfate

Question 9

Which of the following best describes the dissolution of acetic acid ($$\mathrm{CH_3COOH}) in $$water?

Accepted Answer

$$\mathrm{CH_3COOH(aq) \rightleftharpoons CH_3COO^-(aq) + H^+(aq)} ($$partial ionization, equilibrium arrow)

Question 10

Which of the following is the correct molar mass of $$\mathrm{Ca(NO_3$)_2}$$?

Accepted Answer

$$164.10\ \mathrm{g/mol}$$

Question 11

Which of the following is a correct net ionic equation for the precipitation reaction between aqueous solutions of potassium iodide and lead(II) nitrate?

Accepted Answer

$$\mathrm{Pb$$^{2+}$$(aq) + 2I^-(aq) \rightarrow $$PbI_2$$(s)}$$

Question 12

A solution is prepared by dissolving 5.00 g of $$\mathrm{NaCl} in $$enough water to make 250.0 mL of solution. What is the molarity of the solution? ($$\mathrm{M_{NaCl}} = 58.44\ \mathrm{g/mol})$$

Accepted Answer

$$\mathrm{M} = \frac{5.00\ \mathrm{g}}{58.44\ \mathrm{g/mol} 	imes 0.2500\ \mathrm{L}} = 0.342\ \mathrm{M}$$

Question 13

Which of the following is the correct name for $$\mathrm{N_2O_5}$$?

Accepted Answer

Dinitrogen pentoxide

Question 14

Which of the following is a nonelectrolyte when dissolved in water?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} ($$glucose)

Question 15

Which of the following is the correct balanced chemical equation for the reaction of aluminum with hydrochloric acid?

Accepted Answer

$$\mathrm{2Al(s) + 6HCl(aq) \rightarrow 2AlCl_3(aq) + 3H_2(g)}$$

Question 16

A reaction has a theoretical yield of 12.0 g, but only 9.0 g of product is actually obtained. What is the percent yield?

Accepted Answer

$$\mathrm{Percent\ yield = \frac{9.0\ g}{12.0\ g} 	imes 100\% = 75\%}$$

Question 17

Which of the following is the correct formula for ammonium phosphate?

Accepted Answer

$$\mathrm{(NH_4$)_3PO_4}$$

Question 18

Which of the following is a strong acid?

Accepted Answer

$$\mathrm{$$HNO_3$$} ($$nitric acid)

Question 19

Which of the following best describes the process of preparing a solution of known molarity from a solid solute?

Accepted Answer

Weigh the required mass of solute, dissolve it in less than the final volume of solvent, transfer to a volumetric flask, and dilute to the mark.

CHEM105 Exam 3 Study Guide: Stoichiometry, Solutions, Acids & Bases

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