Chemical Quantities (Calculations)

How many moles are in 16.94g of water?

• 16.94 mol H₂O
• 0.9401 mol H₂O
• 305.3 mol H₂O
• 1.063 mol H₂O

How many grams are in 1.2 x 10²⁴ molecules of CO?

• 28 grams
• 56 grams
• 6.02 grams
• 1.2 grams

A container with a volume of 893 L contains how many moles of air at STP?

• 20003.2 mol

• 39.9 mol

• 22.4 mol

• none of the choices

What is the percent composition of Benzene, C₆H₆?

• C = 50%
  H = 50%
• C = 85.7 %
  H = 14.3%
• C = 92.2%
  H = 7.8%
• C = 71.9%
  H = 28.1%

If 45.0 g of Mg react with 19.5 g of oxygen, what is the % of magnesium in the resulting compound?

• 69.8%

• 30.2%

• 43.3%

• 12.9%

What is the empirical formula for C₄H₆?

• CH

• CH₃

• C₂H₃

• C₄H₆

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇
• C₂H₄O₂ and C₆H₁₂O₆
• C₃H₆O₃ and C₂H₆O₂
• CH₄ and C₂H₆

You are given the following percentages: 40.05% S and 59.95% O. Find the empirical formula for these elements. (keep two decimal places throughout calculations)

• SO
• SO₂
• SO₃
• SO₄

What is the molecular formula if the empirical formula is C₂H₅ and the molecular molar mass is 58.14 g/mol?

• C₂H₅
• C₄H₁₀
• C₁H_2.5
• C₄H₈

Balance the following reaction :
 
CaC₂(s)   +   H₂O(l)   -->   C₂H₂(g)   +   Ca(OH)₂(aq)

• 1,2,2,2
• 1,2,1,1
• 2,1,1,1
• 2,1,2,1