Q: A sample of glucose ($$\mathrm{C_6H_{12}O_6$}) $$weighing 18.0 g is completely combusted in excess oxygen. How many molecules of glucose are present in the sample? (Molar mass of glucose = 180.0 g/mol, Avogadro's number $$= 6.022 \times 10$$^{23}$$ mol$$^{-1}$$)

$$6.02 \times 10$$^{22}$$ molecules

Question 1

A sample of glucose ($$\mathrm{C_6H_{12}O_6$}) $$weighing 18.0 g is completely combusted in excess oxygen. How many molecules of glucose are present in the sample? (Molar mass of glucose = 180.0 g/mol, Avogadro's number $$= 6.022 	imes 10$$^{23}$$ mol$$^{-1}$$)

Accepted Answer

$$6.02 	imes 10$$^{22}$$ molecules

Question 2

A compound is found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 3

Which of the following is the correctly balanced chemical equation for the combustion of propane ($$\mathrm{C_3H_8}) in $$oxygen?

Accepted Answer

$$\mathrm{C_3H_8} + 5\mathrm{O_2$} \rightarrow 3\mathrm{CO_2$} + 4\mathrm{H_2O}$$

Question 4

If 10.0 g of $$\mathrm{$$CaCO_3$$}$$ reacts with excess $$\mathrm{HCl}$$ according to the equation $$\mathrm{$$CaCO_3$$} + 2\mathrm{HCl} \rightarrow \mathrm{$$CaCl_2$$} + \mathrm{CO_2$} + \mathrm{H_2O}$$, how many grams of $$\mathrm{CO_2$}$$ are produced? (Molar mass: $$\mathrm{$$CaCO_3$$} = 100.1 g/$$mol, $$\mathrm{CO_2$} = 44.0 g/$$mol)

Accepted Answer

4.40 g

Question 5

A reaction mixture contains 5.0 g of $$\mathrm{Al}$$ and 10.0 g of $$\mathrm{Cl_2$}$$, which react according to $$2\mathrm{Al} + 3\mathrm{Cl_2$} \rightarrow 2\mathrm{$$AlCl_3$$}. $$Which reactant is the limiting reactant?

Accepted Answer

$$\mathrm{Cl_2$}$$

Question 6

In a laboratory experiment, 2.50 g of $$\mathrm{$$CuSO_4$$} is $$obtained from a reaction with a theoretical yield of 3.00 g. What is the percent yield?

Accepted Answer

83.3%

Question 7

Which of the following is the correct chemical equation for the combustion of ethanol ($$\mathrm{C_2H_5OH}$$)?

Accepted Answer

$$\mathrm{C_2H_5OH} + 3\mathrm{O_2$} \rightarrow 2\mathrm{CO_2$} + 3\mathrm{H_2O}$$

Question 8

Which of the following equations correctly represents the reaction between sodium metal and chlorine gas?

Accepted Answer

$$2\mathrm{Na} + \mathrm{Cl_2$} \rightarrow 2\mathrm{NaCl}$$

Question 9

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

Accepted Answer

0.342 M

Question 10

How many grams of $$\mathrm{AgCl} ($$molar mass = 143.32 g/mol) will precipitate when 50.0 mL of 0.200 M $$\mathrm{$$AgNO_3$$} is $$mixed with 50.0 mL of 0.200 M $$\mathrm{NaCl}$$? The reaction is $$\mathrm{$$AgNO_3$$} + \mathrm{NaCl} \rightarrow \mathrm{AgCl} + \mathrm{$$NaNO_3$$}.$$

Accepted Answer

1.43 g

Question 11

Which of the following compounds is soluble in water and acts as a strong electrolyte?

Accepted Answer

$$\mathrm{Na_2SO_4}$$

Question 12

Which of the following is the correct molecular equation for the precipitation reaction between aqueous solutions of $$\mathrm{Pb(NO_3$)_2}$$ and $$\mathrm{KI}$$?

Accepted Answer

$$\mathrm{Pb(NO_3$)_2} (aq) + 2\mathrm{KI} (aq) \rightarrow 2\mathrm{$$KNO_3$$} (aq) + \mathrm{$$PbI_2$$} (s)$$

Question 13

Express the following molecular equation as a net ionic equation: $$\mathrm{$$BaCl_2$$} (aq) + \mathrm{Na_2SO_4} (aq) \rightarrow 2\mathrm{NaCl} (aq) + \mathrm{$$BaSO_4$$} (s).$$

Accepted Answer

$$\mathrm{Ba$$^{2+}$$} (aq) + \mathrm{SO_4$^{2-}} (aq) \rightarrow \mathrm{$$BaSO_4$$} (s)$$

Question 14

Which of the following is the correct net ionic equation for the neutralization of hydrochloric acid with ammonia ($$\mathrm{NH_3$}$$)?

Accepted Answer

$$\mathrm{H^+} (aq) + \mathrm{NH_3$} (aq) \rightarrow \mathrm{NH_4$^+} (aq)$$

Question 15

A 25.0 mL sample of 0.100 M $$\mathrm{HCl} is $$titrated with 0.0500 M $$\mathrm{NaOH}. $$What volume of $$\mathrm{NaOH} is $$required to reach the equivalence point?

Accepted Answer

50.0 mL

Question 16

Which of the following is a correct molecular equation for a gas-evolution reaction between sodium carbonate and hydrochloric acid?

Accepted Answer

$$\mathrm{Na_2CO_3} (aq) + 2\mathrm{HCl} (aq) \rightarrow 2\mathrm{NaCl} (aq) + \mathrm{H_2O} (l) + \mathrm{CO_2$} (g)$$

Question 17

Determine the oxidation state of sulfur in $$\mathrm{H_2SO_4}.$$

Accepted Answer

+6

Question 18

Which of the following reactions is a redox reaction, and what are the oxidizing and reducing agents?

$$\mathrm{Zn} (s) + \mathrm{$$CuSO_4$$} (aq) \rightarrow \mathrm{$$ZnSO_4$$} (aq) + \mathrm{Cu} (s)$$

Accepted Answer

Redox; oxidizing agent: $$\mathrm{Cu$$^{2+}$$}$$, reducing agent: $$\mathrm{Zn}$$

Question 19

Which of the following redox reactions is spontaneous under standard conditions?

Accepted Answer

$$\mathrm{2Ag^+} (aq) + \mathrm{Cu} (s) \rightarrow 2\mathrm{Ag} (s) + \mathrm{Cu$$^{2+}$$} (aq)$$

Chemical Reactions, Stoichiometry, and Aqueous Solutions: Study Notes

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