Q: Which of the following is the correct formula for calculating percent yield?

$$\mathrm{\frac{\text{actual yield}}{\text{theoretical yield}} \times 100\%}$$

Question 1

Which of the following best describes why chemical equations must be balanced?

Accepted Answer

To conserve mass by having the same number of each type of atom on both sides of the equation.

Question 2

Given the balanced equation $$\mathrm{CH_4$(g) + 2O_2(g) \rightarrow CO_2$(g) + 2H_2O(g)}$$, how many grams of water are produced from 50.0 g of methane ($$\mathrm{CH_4$}$$)? (Molar masses: $$\mathrm{CH_4$} = 16.0 g/$$mol, $$\mathrm{H_2O} = 18.0 g/$$mol)

Accepted Answer

112.5 g

Question 3

A solution is made by dissolving 10.0 g of NaCl in enough water to make 500.0 mL of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$0.171\ \mathrm{M}$$

Question 4

Which of the following statements about strong acids is correct?

Accepted Answer

Strong acids completely dissociate in water.

Question 5

Which of the following compounds will form a precipitate when mixed with a solution of $$\mathrm{$$AgNO_3$$}$$?

Accepted Answer

$$\mathrm{NaCl}$$

Question 6

What is the net ionic equation for the reaction between $$\mathrm{NaOH(aq)}$$ and $$\mathrm{HCl(aq)}$$?

Accepted Answer

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

Question 7

A student needs to prepare 250.0 mL of a 0.100 M $$\mathrm{H_2SO_4}$$ solution from a 1.00 M stock solution. What volume of the stock solution should be used?

Accepted Answer

50.0 mL

Question 8

Which of the following best describes a saturated solution?

Accepted Answer

A solution that contains the maximum amount of solute that can dissolve at a given temperature.

Question 9

Which of the following is a correct application of the ideal gas law $$PV = nRT$$?

Accepted Answer

Determining the volume of a gas at a given pressure, temperature, and number of moles.

Question 10

A 2.00 L sample of oxygen gas is at 793 Torr and 25.0°C. If the volume is expanded to 4.00 L and the pressure is reduced to 511 Torr, what is the final temperature in Kelvin? (Use the combined gas law.)

Accepted Answer

$$T_2 = 387$$\ \mathrm{K}$$

Question 11

Which of the following is true about electrolytes in aqueous solution?

Accepted Answer

They conduct electricity because ions move freely in solution.

Question 12

Which of the following is the correct net ionic equation for the precipitation reaction between $$\mathrm{Pb(NO_3$)_2(aq)}$$ and $$\mathrm{2KI(aq)}$$?

Accepted Answer

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

Question 13

Which of the following is a correct statement about oxidation and reduction?

Accepted Answer

Oxidation is the loss of electrons; reduction is the gain of electrons.

Question 14

A sample of $$\mathrm{H_2$}$$ gas has a density of $$0.09000\ \mathrm{g/L} at $$STP. What is the molar mass of $$\mathrm{H_2$}$$? (Molar volume at STP = $$22.4\ \mathrm{L/mol})$$

Accepted Answer

$$2.016\ \mathrm{g/mol}$$

Question 15

Which of the following ions is always soluble in water?

Accepted Answer

$$\mathrm{NO_3$^-}$$

Question 16

A 0.100 L sample of 0.500 M HBr is titrated with 0.200 M NaOH. What volume of NaOH is required to reach the equivalence point? (Reaction: $$\mathrm{HBr(aq) + NaOH(aq) \rightarrow NaBr(aq) + H_2O(l)})$$

Accepted Answer

0.250 L

Question 17

Which of the following best describes a limiting reagent in a chemical reaction?

Accepted Answer

The reactant that is completely consumed and determines the amount of product formed.

Question 18

Which of the following is the correct formula for calculating percent yield?

Accepted Answer

$$\mathrm{\frac{	ext{actual yield}}{	ext{theoretical yield}} 	imes 100\%}$$

Question 19

Which of the following best describes the role of water in an aqueous solution?

Accepted Answer

Water is the solvent, present in the greatest amount.

Chemical Reactions, Stoichiometry, Solutions, and Gases: Core Concepts in General Chemistry

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