Unit 5-6 Exam Review

What is percent composition?

• mass of each element in a compound compare to total mass of compound

• percent of a compound in a mixture

• percent of molecular mass compared to empirical mass

• mass of one mole of a substance

g/mol is the unit for

• mass

• particles

• molar mass

• percent composition

A compound's formula is CH₄N. If the molar mass is 60.0 g/mol, what is the molecular formula?

• CH₄N

• C₂H₈N₂

• C₂H₄N₂

• CHN

What is the mass of 6.022x10^23 atoms of carbon?

• 32.065 g

• 24.022 g

• 12.011g

• 15.999 g

The mass of one mole of a substance best describes the

• percent composition

• molecular formula

• empirical formula

• molar mass

The total mass of a compound is 62.0 g. When the compound is broke down, it is found to have 23.4 g of sodium. What is the percent by mass of sodium in this compound?

• 2.64%

• 37.7%

• 27.4%

• 23.4%

What is the best description for an empirical formula?

• the mass of each element in a compound compare to the entire mass of a compound

• the actual number of each atom in a compound

• the simplest whole number ratio of elements in a compound

• the mass of one mole of a substance

Which of the following is an empirical formula?

• N₂H₂

• N₂H₄

• NH₂

• N₄H₈

The molar mass of CO₂ is 44.01 g/mol. How many moles of CO₂ are present in 86.6 g of compound?

• 3811 mol

• 86.8 mol

• 0.508 mol

• 1.97 mol

The percent composition of carbon in CO₂ is about 27%. What is the percent oxygen in this compund?

• 73%

• 36%

• 41%

• 12%