# Worksheet: Formula Mass

In this worksheet, we will practice defining formula mass and calculating its value for given molecular formulas using atomic masses.

**Q2: **

To the nearest g/mol, what is the relative formula mass of (sodium oxide)?

**Q3: **

What is the M_{r} of phosphorus trifluoride ?

**Q4: **

What is the of silane ?

**Q5: **

What is the of xenon difluoride ?

**Q6: **

The relative atomic mass (A_{r}) of sodium is 23 g/mol, that of oxygen is 16 g/mol, and that of hydrogen is 1 g/mol. What is the relative formula mass (M_{r}) of (sodium hydroxide)?

**Q7: **

Using the Periodic Table to find the relative atomic masses of its elements, calculate the relative formula mass (M_{r}) of (carbon dioxide) to the nearest g/mol.

**Q8: **

Using the Periodic Table to find the relative atomic masses of its elements, calculate the relative formula mass of (formaldehyde).

**Q9: **

What is the relative formula mass of (methanol)? Use the periodic table to find the relative atomic masses of the elements.

**Q10: **

What is the relative formula mass of (magnesium fluoride)?

**Q11: **

What is the relative formula mass of (ammonia)?

**Q12: **

A substance has the formula unit . What is the relative formula mass of this substance in terms of and , the relative atomic masses of and ?

- A
- B
- C
- D

**Q13: **

A substance has the formula unit . What is the relative formula mass of this substance in terms of and , the relative atomic masses of and ?

- A
- B
- C
- D
- E

**Q14: **

The relative atomic mass of carbon is 12 g/mol, and the of oxygen is 16 g/mol. What is the relative formula mass of (carbon monoxide)?

**Q15: **

The relative atomic mass (A_{r}) of carbon is 12 g/mol, and the A_{r} of hydrogen is 1 g/mol. What is the relative formula mass (M_{r}) of (methane)?

**Q16: **

The displayed formula for -tribromocyclohexane is shown below. What is its relative formula mass? Give your answer to the nearest whole number.

**Q17: **

What is the relative formula mass of ?

**Q18: **

Which of the following compounds has a relative formula mass of 44?

- A
- B
- C
- D
- E

**Q19: **

Tricalcium phosphate is an anticaking agent that prevents granular food from forming lumps. The chemical equation for the production of is shown below.

Which compound has the largest relative formula mass?

- A
- B and
- C
- D
- E

**Q20: **

The balanced equation for the oxidation of an organic molecule is shown below. The total relative formula mass of the products is 96. Identify what compound is.

- A
- B
- C
- D
- E

**Q21: **

The atomic mass unit (u) is defined as th of the mass of an atom of carbon-12. What is the mass of a silicon-30 atom in atomic mass units?

**Q22: **

The atomic mass unit (u) is defined as th of the mass of an atom of carbon-12. What is the mass of a fluorine-19 atom in atomic mass units?

**Q23: **

The relative atomic mass of an element is the average mass of one atom on a scale .

- Awhere hydrogen-1 has a mass of 1
- Bwhere carbon-12 has a mass of 12
- Cwhere the most common isotope of the element has a mass of 100
- Dfrom 0โ100, where 0 is the mass of hydrogen and 100 is the mass of the heaviest element

**Q24: **

A scientist is given the chemical formula and the relative formula mass of two unknown compounds, as shown below. If the atomic mass of element is twice that of element , which of the following are elements and ?

- A,
- B,
- C,
- D,
- E,