Percent Composition Calculations

Chemistry ⇒ Stoichiometry and Chemical Calculations

Percent Composition Calculations starts at 9 and continues till grade 12. QuestionsToday has an evolving set of questions to continuously challenge students so that their knowledge grows in Percent Composition Calculations. How you perform is determined by your score and the time you take. When you play a quiz, your answers are evaluated in concept instead of actual words and definitions used.

See sample questions for grade 9

A 100 g sample of a compound contains 40 g of sulfur and 60 g of oxygen. What is the percent composition of oxygen?

A 200 g sample of a compound contains 80 g of oxygen. What is the percent composition of oxygen?

A 50 g sample of a compound contains 10 g of hydrogen. What is the percent composition of hydrogen?

A compound contains 12 g of carbon, 2 g of hydrogen, and 16 g of oxygen. What is the percent composition of hydrogen?

A compound contains 24 g of carbon and 64 g of oxygen. What is the percent composition of carbon in the compound?

A compound has a molar mass of 100 g/mol and contains 20 g of hydrogen per mole. What is the percent composition of hydrogen?

A compound has a percent composition of 52.2% carbon, 13.0% hydrogen, and 34.8% oxygen. What is the empirical formula?

A student claims that the percent composition of sodium in Na₂SO₄ is 50%. Is this claim correct? Explain your answer. (Na = 23, S = 32, O = 16)

Which of the following best describes why percent composition is important in chemistry? (1) It helps identify unknown compounds. (2) It determines the color of a compound. (3) It measures the temperature of a reaction. (4) It tells the boiling point of a compound.

Which of the following compounds has the highest percent by mass of oxygen? (1) H₂O (2) CO₂ (3) SO₂ (4) Na₂O (H = 1, C = 12, O = 16, S = 32, Na = 23)

Which of the following compounds has the lowest percent by mass of hydrogen? (1) H₂O (2) CH₄ (3) NH₃ (4) C₂H₆ (H = 1, C = 12, N = 14, O = 16)

Which of the following is NOT a use of percent composition? (1) Identifying unknown substances (2) Calculating empirical formulas (3) Determining melting point (4) Checking purity of a sample

Fill in the blank: The percent composition of calcium in CaCO₃ (Ca = 40, C = 12, O = 16) is ______%.

Fill in the blank: The percent composition of chlorine in KCl (K = 39, Cl = 35.5) is ______%.

Fill in the blank: The percent composition of iron in Fe₂O₃ (Fe = 56, O = 16) is ______%.

Fill in the blank: The percent composition of nitrogen in (NH₄)₂SO₄ (N = 14, H = 1, S = 32, O = 16) is ______%.

True or False: Percent composition can be calculated for both elements and compounds.

True or False: Percent composition can be used to check the purity of a chemical sample.

True or False: Percent composition can be used to determine the empirical formula of a compound.

True or False: The percent composition of a compound depends on the amount of sample taken.