Question

Test 2 CHE 111 Name Danielle Hot 1. (10 pts) Using molar mass, determine the following: maior mons =MIL a. The number of moles in 15 grams of Naci. b. The number of moles in 15 grams of Na S04. C. The mass of 3 moles of CaCO3- d. The mass of 3 moles of MgCO3. e. The mass of 0.4 moles of NH3. 2. (10 pts) Balance a. CzH6 + 02 → CO2 + H20

Answer 1

1a) Molar mass of NaCl = 58.5 g/mol

Moles = mass/molar mass = 15/58.5 = 0.256 moles

b) Molar mass of Na2SO4 = 142 g/mol

Moles = 15/142 = 0.106 moles

c) Molar mass of CaCO3 = 100 g/mol

1 mole contain 100 g

3 mole contain 3×100 = 300 g

d) Molar mass of MgCO3 = 84.31 g/mol

1 mole MgCO3 contain 84.31 g

3 mole MgCO3 contain 3×84.31 = 252.93 g

e) Molar mass of NH3 = 17 g/mol

1 mole NH3 contain 17 g

0.4 mole NH3 contain 17×0.4 = 6.8 g

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