Q: How many molecules are present in 0.789 moles of ammonia ($$NH_3$$)?

$$1.31 \times 10$$^{24}$$ molecules

Q: How many atoms of carbon are in a 4.56-gram sample of methane ($$CH_4$$)? (Molar mass $$= 16.04\ g/mol)$$

$$1.71 \times 10$$^{23}$$ atoms

Question 1

Which of the following best describes the type of reaction represented by the equation $$2NH_3(g) \rightarrow N_2$(g) + 3H_2(g)$$?

Accepted Answer

Decomposition reaction

Question 2

What is the balanced chemical equation for the reaction between solid magnesium and gaseous nitrogen to form solid magnesium nitride?

Accepted Answer

$$3Mg(s) + N_2$(g) \rightarrow Mg_3N_2(s)$$

Question 3

Calculate the formula weight of calcium nitrate, $$Ca(NO_3$)_2$$, using the periodic table provided.

Accepted Answer

$$164.10\ 	ext{amu}$$

Question 4

How many molecules are present in 0.789 moles of ammonia ($$NH_3$$)?

Accepted Answer

$$1.31 	imes 10$$^{24}$$ molecules

Question 5

A compound is found to be 27.0% S, 13.4% O, and 59.6% Cl by mass. What is its empirical formula?

Accepted Answer

$$SOCl_2$$

Question 6

What is the percentage by mass of oxygen in $$KMnO_4$$?

Accepted Answer

$$40.5\%$$

Question 7

How many grams of $$CO_2$$ are produced from the complete combustion of 7.010 grams of glucose ($$C_6H_{12}O_6$)? (Molar mass of C_6H$$_{12}$$O_6 = 180.16$$\ g/mol$$, CO_2$ = 44.01\ g/mol)$$

Accepted Answer

$$10.29\ g$$

Question 8

Which of the following is the correct molar mass for dinitrogen pentoxide ($$N_2O_5$$)?

Accepted Answer

$$108.02\ g/mol$$

Question 9

If 3.0 g of $$N_2 is $$mixed with 3.0 g of $$H_2 in $$the reaction $$N_2(g) + 3H_2(g$$) \rightarrow 2NH_3(g)$$, which is the limiting reactant?

Accepted Answer

$$H_2$$

Question 10

A sample contains $$1.60 	imes 10$$^{21}$$ molecules of CO_2$. What is the mass of this sample in grams? (M$$_{$$CO_2$$} = 44.01\ g/mol$$)

Accepted Answer

$$0.117\ g$$

Question 11

Which of the following best describes the reaction: $$CH_4(g) + 2O_2(g$$) \rightarrow $$CO_2(g) + 2H_2O(l$$)$$?

Accepted Answer

Combustion reaction

Question 12

What is the empirical formula of a compound if a 2.144 g sample contains 0.260 g C, 0.347 g O, and 1.537 g Cl?

Accepted Answer

$$COCl_2$$

Question 13

How many atoms of carbon are in a 4.56-gram sample of methane ($$CH_4$$)? (Molar mass $$= 16.04\ g/mol)$$

Accepted Answer

$$1.71 	imes 10$$^{23}$$ atoms

Question 14

A compound has an empirical formula of $$CH_2O$$ and a molecular weight of $$180\ g/mol. $$What is its molecular formula?

Accepted Answer

$$C_6H_{12}O_6$

Question 15

Which of the following is the correct sequence of steps to determine the limiting reactant in a chemical reaction?

Accepted Answer

Convert grams to moles, use the molar ratio, compare required and available amounts

Question 16

What is the maximum mass of ammonia ($$NH_3) $$that can be produced when 3.0 g of $$N_2$$ reacts with 3.0 g of $$H_2$$? ($$M_{N_2$} = 28.02\ g/mol$$, $$M_{H_2$} = 2.02\ g/mol$$, $$M_{NH_3$} = 17.03\ g/mol)$$

Accepted Answer

$$5.06\ g$$

Question 17

Which of the following is the correct balanced equation for the reaction of solid calcium carbonate with aqueous hydrochloric acid?

Accepted Answer

$$CaCO_3(s) + 2$$HCl(aq) \rightarrow $$CO_2(g$$) + $$CaCl_2(aq) + H_2O(l$$)$$

Question 18

If the actual yield of $$CO_2 in a $$reaction is 50.0 g and the theoretical yield is 68.0 g, what is the percent yield?

Accepted Answer

$$73.5\%$$

Chemical Reactions and Stoichiometry: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards