Q: If 2.891 g $$\mathrm{$$MgCl_2$$} is $$dissolved in enough water to make 500.0 mL of solution, what is the molarity of the magnesium chloride solution? (Molar mass $$\mathrm{$$MgCl_2$$} = 95.21 g/$$mol)

6.073 \times $$10^{-2}$$\ \mathrm{M}

Question 1

What is the mass percent of chlorine in iron(II) chloride ($$\mathrm{$$FeCl_2$$}$$)? (Atomic masses: Fe = 55.85, Cl = 35.45)

Accepted Answer

55.9\%

Question 2

A sample of dichloromethane ($$\mathrm{CH_2Cl_2}) is $$analyzed. What is the mass percent of each element in the compound? (Atomic masses: C = 12.01, H = 1.008, Cl = 35.45)

Accepted Answer

14.14\%\ \mathrm{C},\ 2.37\%\ \mathrm{H},\ 83.48\%\ \mathrm{Cl}

Question 3

A nitrogen oxide contains 46.68\% nitrogen by mass. What is its empirical formula? (Atomic masses: N = 14.01, O = 16.00)

Accepted Answer

NO

Question 4

A molecule is found to contain 47.35\% C, 10.60\% H, and 42.05\% O by mass. What is its empirical formula?

Accepted Answer

C_3H_8O_2

Question 5

A 1.031-g sample of a compound containing only C, H, and O produces 2.265 g of $$\mathrm{CO_2$}$$ and 1.236 g of $$\mathrm{H_2O}$$ upon combustion. What is the empirical formula of the compound?

Accepted Answer

C_3H_8O

Question 6

Cyclohexene, a hydrocarbon, has a molar mass of 82.1 g/mol. If combustion of 0.8300 g cyclohexene produces 0.9102 g $$\mathrm{H_2O}$$ and 2.668 g $$\mathrm{CO_2$}$$, what is the molecular formula of cyclohexene?

Accepted Answer

C_6H_{10}

Question 7

When methanol undergoes complete combustion, the products are carbon dioxide and water. What are the respective coefficients when the equation is balanced with the smallest whole numbers?

$$\_\_\ \mathrm{CH_3OH}(l) + \_\_\ \mathrm{O_2$}(g) \rightarrow \_\_\ \mathrm{CO_2$}(g) + \_\_\ \mathrm{H_2O}(g)$$

Accepted Answer

2, 3, 2, 4

Question 8

Iron reacts with hydrochloric acid to produce iron(II) chloride and hydrogen gas:

$$\mathrm{Fe}(s) + 2\ \mathrm{HCl}(aq) \rightarrow \mathrm{$$FeCl_2$$}(aq) + \mathrm{H_2$}(g)$$

How many moles of HCl will react with 4.6 moles of Fe?

Accepted Answer

9.2\ \mathrm{mol}

Question 9

Which of the following statements about the combustion of propane is INCORRECT?

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

Accepted Answer

Three grams of carbon dioxide are formed per five grams of oxygen consumed.

Question 10

Aluminum reacts with oxygen to produce aluminum oxide:

$$4\ \mathrm{Al}(s) + 3\ \mathrm{O_2$}(g) \rightarrow 2\ \mathrm{Al_2O_3}(s)

If 5.0 $$moles of Al react with excess $$\mathrm{O_2$}$$, how many moles of $$\mathrm{Al_2O_3}$$ can be formed?

Accepted Answer

2.5\ \mathrm{mol}

Question 11

Dinitrogen trioxide ($$\mathrm{N_2O_3}) $$decomposes to form nitrogen monoxide and nitrogen dioxide gases. What mass of nitrogen dioxide is formed from the decomposition of 13.1 g of $$\mathrm{N_2O_3}$$? (Molar masses: $$\mathrm{N_2O_3} = 76.01 g/$$mol, $$\mathrm{NO_2$} = 46.01 g/$$mol)

$$\mathrm{N_2O_3}(s) \rightarrow \mathrm{NO}(g) + \mathrm{NO_2$}(g)$$

Accepted Answer

7.93\ \mathrm{g}

Question 12

If 0.250 moles of bromine and 0.600 moles of ammonia react according to the equation below, what is the maximum amount of ammonium bromide (in moles) produced?

$$3\ \mathrm{Br_2$}(l) + 8\ \mathrm{NH_3$}(g) \rightarrow 6\ \mathrm{NH_4Br}(s) + \mathrm{N_2$}(g)$$

Accepted Answer

0.450\ \mathrm{mol}

Question 13

What mass of carbon dioxide is produced by the complete combustion of 5.50 grams of hexane ($$\mathrm{C_6H_{14}}$$)? (Molar mass $$\mathrm{C_6H_{14}} = 86.18 g/$$mol, $$\mathrm{CO_2$} = 44.01 g/$$mol)

$$2\ \mathrm{C_6H_{14}} + 19\ \mathrm{O_2$} \rightarrow 12\ \mathrm{CO_2$} + 14\ \mathrm{H_2O}$$

Accepted Answer

16.9\ \mathrm{g}

Question 14

Sulfur trioxide is made from the reaction of sulfur dioxide and oxygen:

$$2\ \mathrm{SO_2$}(g) + \mathrm{O_2$}(g) \rightarrow 2\ \mathrm{SO_3$}(g)$$

How many grams of $$\mathrm{SO_3$}$$ can be made from the reaction of 3.00 g $$\mathrm{SO_2$}$$ with 2.02 g $$\mathrm{O_2$}$$? (Molar masses: $$\mathrm{SO_2$} = 64.07 g/$$mol, $$\mathrm{O_2$} = 32.00 g/$$mol, $$\mathrm{SO_3$} = 80.07 g/$$mol)

Accepted Answer

3.75\ \mathrm{g}

Question 15

What mass of carbon reacts completely with 17.8 grams of $$\mathrm{$$SiO_2$$}$$ according to the following equation?

$$\mathrm{$$SiO_2$$}(s) + 3\ \mathrm{C}(s) \rightarrow \mathrm{SiC}(s) + 2\ \mathrm{CO}(g)

($$Molar masses: $$\mathrm{$$SiO_2$$} = 60.09 g/$$mol, C = 12.01 g/mol)

Accepted Answer

10.7\ \mathrm{g}

Question 16

Disulfur dichloride is produced by reacting chlorine gas with molten sulfur:

$$\mathrm{S_8$}(l) + 4\ \mathrm{Cl_2$}(g) \rightarrow 4\ \mathrm{S_2Cl_2}(g)$$

What is the percent yield if 6.25 g $$\mathrm{S_2Cl_2} is $$isolated from the reaction of 10.0 g $$\mathrm{S_8$}$$ and 7.50 g $$\mathrm{Cl_2$}$$? (Molar masses: $$\mathrm{S_8$} = 256.56 g/$$mol, $$\mathrm{Cl_2$} = 70.90 g/$$mol, $$\mathrm{S_2Cl_2} = 135.04 g/$$mol)

Accepted Answer

43.8\%

Question 17

Under certain conditions, the reaction of ammonia with excess oxygen produces a 38.2\% yield of NO. How many grams of $$\mathrm{NH_3$}$$ must be reacted with excess oxygen to produce 17.5 g of NO?

$$4\ \mathrm{NH_3$}(g) + 5\ \mathrm{O_2$}(g) \rightarrow 4\ \mathrm{NO}(g) + 6\ \mathrm{H_2O}(g)

($$Molar masses: $$\mathrm{NH_3$} = 17.03 g/$$mol, NO = 30.01 g/mol)

Accepted Answer

26.0\ \mathrm{g}

Question 18

If 2.891 g $$\mathrm{$$MgCl_2$$} is $$dissolved in enough water to make 500.0 mL of solution, what is the molarity of the magnesium chloride solution? (Molar mass $$\mathrm{$$MgCl_2$$} = 95.21 g/$$mol)

Accepted Answer

6.073 	imes $$10^{-2}$$\ \mathrm{M}

Question 19

What is the mass of solute in 225 mL of $$5.91 	imes 10$$^{-2}$$ M $$\mathrm{$$KIO_3$$}$$? (Molar mass $$\mathrm{$$KIO_3$$}$$ = 214.00 g/mol)

Accepted Answer

2.85\ \mathrm{g}

Question 20

If 0.10 mole of each of the following compounds is dissolved to a volume of 1.0 L in water, which one will have the highest concentration of dissolved ions?

Accepted Answer

Al($$NO_3)_3$$

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