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Question 1

What is the empirical formula of a compound containing 60.0% sulfur and 40.0% oxygen by mass?

Question 2

A compound is found to contain 23.3% magnesium, 30.7% sulfur, and 46.0% oxygen. What is the empirical formula of this compound?

Question 3

What is the empirical formula for a compound containing 38.8% carbon, 16.2% hydrogen, and 45.1% nitrogen?

Question 4

A sample of an oxide of nitrogen is found to contain 30.4% nitrogen. What is its empirical formula?

Question 5

A sample of an oxide of arsenic is found to contain 75.74% arsenic. What is its empirical formula?

Question 6

What is the empirical formula for a compound containing 26.57% potassium, 35.36% chromium, and 38.07% oxygen?

Question 7

A compound with an empirical formula of C2OH4 and a molar mass of 88. What is the molecular formula of this compound?

Question 8

A compound with an empirical formula of C4H4O and a molar mass of 136. What is the molecular formula of this compound?

Question 9

A compound that is 9.4% C, 14.9% F, 62.7% Br, and 6.3% Oxygen has a molar mass of 237.8. What is the molecular formula of this compound?

Question 10

A carbohydrate on analysis gave the following composition: carbon = 40.0%; hydrogen = 6.71%, and oxygen made up the rest. Calculate the molecular formula of this organic compound which has a molecular mass of 181.

Question 11

Nicotine is mainly responsible for the addictive nature of cigarettes. A typical cigarette contains 12.33 mg C, 1.45 mg H, & 2.87 mg N. If the molar mass of nicotine is 162 g/mol, what is the molecular formula of nicotine?

Question 12

An unknown compound was found to have a percent composition as follows: 47.0 % potassium, 14.5 % carbon, and 38.5 % oxygen. What is its empirical formula? If the true molar mass of the compound is 166.22 g/mol, what is its molecular formula?

Question 13

NutraSweet is 57.14% C, 6.16% H, 9.52% N, and 27.18% O. Calculate the empirical formula of NutraSweet and find the molecular formula. (The molar mass of NutraSweet is 294.30 g/mol)

Question 14

What’s the empirical formula of a molecule containing 65.5% carbon, 5.5% hydrogen, and 29% Oxygen? If the molar mass is 110 g/mol, what is the molecular formula?

Question 15

Caffeine has the following percent composition: 49.47% C, 5.201% H, 28.84% N, and 16.48% O If the molecular mass of caffeine is 194.2 amu, what is it’s molecular formula?

Question 16

The combustion of 3.42 g of a compound is known to contain only nitrogen and hydrogen gave 9.82 g of NO₂ and 3.85 g of water. Determine the empirical formula of this compound.

Question 17

A 2.52 g sample of a compound containing carbon, hydrogen, nitrogen, oxygen, and sulfur was burned in excess oxygen gas to yield 4.36 grams of CO₂ and 0.892 grams of H₂O as the only carbon and hydrogen products respectively. Another sample of the same compound of mass 4.14 g yielded 2.60 g of SO₃ as the only sulfur containing product. A third sample of mass 5.66 g was burned under different conditions to yield 2.80 g of HNO₃ as the only nitrogen containing product. Determine the empirical formula of the compound.

Question 18

A compound with a known molecular weight (146.99 g/mol) that contains only C, H, and Cl was studied by combustion analysis. When a 0.367 g sample was combusted, 0.659 g of CO₂ and 0.0892 g of H₂O formed. What are the empirical and molecular formulas?

Question 19

A 6.20-g sample of an unknown compound containing only C, H, and O combusts in an oxygen rich environment. When the products have cooled to 20.0 °C at 1 bar, there are 8.09 L of CO₂ and 3.99 mL of H₂O. The density of water at 20.0 °C is 0.998 g/mL.