In this set of practice problems, we will work on molar calculations such as converting between Mass, Moles, and Number of Ions and Atoms.

For all the problems, **calculating the molar mass** is not shown as it should be a relatively easy task using the periodic table. However, there is a **separate article** dedicated to this, so if you don’t feel comfortable with the concept of molar mass, please read it before working on these examples.

Other related topics are also covered in the following articles:

- Atomic and Molecular Masses
- The Mole and Molar Mass
- How To Calculate The Molar Mass
- How To Convert Grams To Moles
- Grams to Molecules and Molecules to Mass
- How To Convert Grams To Number of Atoms

#### Practice

**Calculating Moles from Mass**

Determine the number of moles in 59.7 grams of Al.

Calculate the number of moles in 0.647 grams of Al_{2}O_{3}.

Determine the number of moles in 3.56 grams of Mg(OH)_{2}.

Determine the number of moles in 0.385 grams of N_{2}O_{3}.

Determine the number of moles in 165 grams of CaSO_{4}.

Calculate the molar mass of N_{2}O_{4} and determine how many moles of it are in a 23.9 g sample.

Calculate the number of moles in 165 grams of C_{3}H_{6}O.

Determine the number of moles in 452 grams of Co(NO_{3})_{3}.

**Calculating Mass from Moles **

Calculate the mass in grams of 0.598 moles of Fe.

Calculate the mass in grams of 0.987 moles of (NH_{4})_{2}S.

Calculate the mass in grams of 6.81 moles of Al_{2}(SO_{4})_{3}.

Calculate the mass in grams of 2.64 moles of methanol, CH_{3}OH.

Calculate the mass in grams of 9.42 moles of NiCl_{2}·6H_{2}O.

**Calculating the Number of Molecules from the Moles**

How many molecules are there in a 0.487 mol sample of PCl_{5}?

How many molecules (formula units) are there in a 5.84 mol sample of Na_{2}SO_{3}.

How many molecules of sucrose, C_{12}H_{22}O_{11} are there in a 0.684 mol sample?

Calculate the number of molecules in a 3.25-mol sample of propane, C_{3}H_{8}.

How many moles is 5.80 x 10^{25} molecules of POCl_{3}?

**Calculating the Number of Molecules from the Mass**

How many molecules are there in a 5.12-g sample of K_{2}O?

How many molecules of glucose, C_{6}H_{12}O_{6} are there in a 35.0 g sample?

Calculate the number of molecules of butane, C_{4}H_{10}, in its 2.40-gram sample.

How many Ethylene, C_{2}H_{4} molecules are present in a 46.2 g sample? The molar mass of C_{2}H_{4} is 28.1 g/mol.

**Calculating the Number of Atoms**

Calculate the number of atoms in a 2.56-g sample of Ca.

How many carbon atoms are there in a 0.590 mol sample of CCl_{4}.

How many carbon atoms are there in a 0.964 mol sample of C_{2}H_{6}.

Which sample contains more Cl atoms: a) 1.25 moles of CH_{2}Cl_{2} b) 2.15 moles of CH_{3}Cl

The molecular formula of morphine is C_{17}H_{19}NO_{3}. How many carbon atoms are in a 34.7-gram sample of morphine?

Isopropyl alcohol, also known as isopropanol, has found a widespread application in the preparation of pharmaceutical products. Answer the following questions considering that the molecular formula of isopropanol is C_{3}H_{8}O.

a) How many moles of C_{3}H_{8}O are contained in a 12.0 g sample of the alcohol?

b) How many molecules of C_{3}H_{8}O are contained in a 12.0 g sample of the alcohol?

c) How many atoms of oxygen are contained in a 12.0 g sample of the isopropyl alcohol (C_{3}H_{8}O)?

d) How many atoms of carbon are contained in a 12.0 g sample of the isopropyl alcohol (C_{3}H_{8}O)?

**Check Also**

- Subatomic particles and Isotopes
- Naming Monatomic and Polyatomic Ions
- Naming Ionic Compounds
- Naming Covalent Compounds
- Naming Acids and Bases
- Atomic and Molecular Masses
- The Mole and Molar Mass
- Percent Composition and Empirical Formula
- Stoichiometry of Chemical Reactions
- Limiting Reactant
**Limiting Reactant Practice Problems**- Reaction/Percent Yield
**Stoichiometry Practice Problems**