chapter 3

What is the molar mass of Cl?

• 16.00 g/mol

• 35.45 g/mol

• 40.08 g/mol

• 22.99 g/mol

How many atoms of oxygen, O, in 6.2 mg (6.2x10−3 g) KMnO4?

• 3.0x10^19

• 2.4x10^15

• 1.2x10^17

• 9.5x10^19

What is the mass of 7.5x10^7 atoms of 19F?

• 1.8x10^-20g

• 2.4x10^-15g

• 3.1x10^-17g

• 5.0x10^-19g

Calculate the % composition of H, P, and O in phosphoric acid, H3PO4.

• 3.1% H, 31.6% P, 65.3% O

• 5.2% H, 28.4% P, 66.4% O

• 2.7% H, 35.2% P, 62.1% O

• 4.5% H, 29.8% P, 65.7% O

Balance the following reaction equations: C2H6 + O2 → CO2 + H2O

• 1,4,3,3

• 2,4,1,3

• 1,6,6,6

• 2,7,4,6

Consider the unbalanced reaction: Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O. Balance the reaction and calculate the amount of calcium phosphate formed when 3.70 g calcium hydroxide reacts with excess phosphoric acid.

• 5.18 g

• 4.90 g

• 6.20 g

• 7.30 g

Cu + HNO3 → Cu(NO3)2 + NO2 + H2O. Balance the reaction and calculate how much copper(II) nitrate will be formed when 31.7 g copper reacts with excess nitric acid.

• 93.3 g

• 105.6 g

• 87.2 g

• 76.8 g

Consider the reaction 2Fe + KClO3 → Fe2O3 + KCl. When 2.46 g Fe is mixed with when 3.68 g KClO3, 2.60 g Fe2O3 is formed. Calculate the %yield of the reaction.

• 74%

• 82%

• 90%

• 68%

What is the average molar mass of potassium?

• 39.1g/mol

• 38.5g/mol

• 40.0g/mol

• 41.0g/mol

An oxide of manganese, Mn, consists of 36.8% O and 63.2% Mn. What is the empirical formula of the oxide?

• Mn2O3

• MnO

• Mn3O4

• MnO2