Moles/Mass/Molecules Practice Problem Worksheet

Complete the following problems:

1. Convert 11.03 moles of calcium nitrate to grams.

2. How many molecules are contained in 103.4g of sulfuric acid?

3. 3.25 x 1024 molecules of dinitrogen pentoxide would be how many moles?

4. What would be the mass of 9.03 x 1021 molecules of hydrobromic acid?

5. A sample of iron (III) chloride has a mass of 26.29g. How many moles would this be?

1. Converting 11.03 moles of calcium nitrate to grams gives 1,809.89 grams.

2. The number of molecules that are contained in 103.4 g of sulfuric acid is    molecules.

3. Converting molecules of dinitrogen pentoxide to moles is equal to 5.3987 moles.

4. The mass of molecules of hydrobromic acid is 1.2135 grams.

5. The number of moles contained in 26.29 g of iron (III) chloride is 0.1621 moles.

Given the following data:

Scientific data:

1. To convert 11.03 moles of calcium nitrate to grams:

Mass of calcium nitrate = 1,809.89 grams.

2. To calculate how many molecules are contained in 103.4 g of sulfuric acid:

First of all, we would determine the number of moles contained in 103.4 g of sulfuric acid.

Number of moles = 1.0543 moles

By stoichiometry:

1 mole of sulfuric acid =  molecules

1.0543 mole of sulfuric acid = X molecules

Cross-multiplying, we have:

X =  molecules

3. To convert molecules of dinitrogen pentoxide to moles:

By stoichiometry:

1 mole of dinitrogen pentoxide =  molecules

X mole of dinitrogen pentoxide = molecules

Cross-multiplying, we have:

X = 5.3987 moles

4. To calculate the mass of molecules of hydrobromic acid:

First of all, we would determine the number of moles contained in molecules of hydrobromic acid.

By stoichiometry:

1 mole of hydrobromic acid =  molecules

X mole of hydrobromic acid =  molecules

Cross-multiplying, we have:

X = 0.015 moles

Mass of hydrobromic acid = 1.2135 grams.

5. To calculate the number of moles contained in 26.29 g of iron (III) chloride:

Number of moles = 0.1621 moles.

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Explanation:

1) Convert 11.03 moles of calcium nitrate to grams.

Given data:

Number of moles = 11.03 mol

Mass of calcium nitrate = ?

Solution:

Formula:

Number of moles = mass / molar mass

Now we will rearrange the formula because we have to calculate the mass.

Mass = number of moles × molar mass

Molar mass of calcium nitrate =  164.088 g/mol

Mass = 11.03 mol ×  164.088 g/mol

Mass = 1809.89 g

2. How many molecules are contained in 103.4g of sulfuric acid?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Given data:

Number of molecules = ?

Mass of sulfuric acid = 103.4 g

Solution:

Formula:

Number of moles = mass / molar mass

Number of moles = 103.4 g/ 98.079 g/mol

Number of moles = 1.05 mol

1 mole =  6.022 × 10²³ molecules

1.05 mol × 6.022 × 10²³ molecules / 1mol

6.323 × 10²³ molecules of sulfuric acid

3. 3.25 x 1024 molecules of dinitrogen pentoxide would be how many moles?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Given data:

Number of molecules of dinitrogen pentoxide = 3.25 × 10²⁴

Moles of dinitrogen pentoxide = ?

Solution:

1 mole =  6.022 × 10²³ molecules

1 mol  × 3.25 × 10²⁴ molecules / 6.022 × 10²³ molecules

5.4 moles

4. What would be the mass of 9.03 x 1021 molecules of hydrobromic acid?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Given data:

Number of molecules of hydrobromic acid = 9.03 × 10²¹

Mass of hydrobromic acid = ?

Solution:

First of all we will calculate the moles of hydrobromic acid.

1 mole =  6.022 × 10²³ molecules

1 mol  × 9.03 × 10²¹ molecules / 6.022 × 10²³ molecules

0.015  moles

Mass of hydrobromic acid:

Mass =  number of moles × molar mass

Mass = 0.015 mol × 80.9 g/mol

Mass =1.21 g

5. A sample of iron (III) chloride has a mass of 26.29g. How many moles would this be?

Given data:

Number of moles =?

Mass of iron(III) chloride = 26.29 g

Solution:

Formula:

Number of moles = mass / molar mass

Molar mass of iron chloride  =  162.2 g/mol

Now we will put the values in formula.

Moles = 26.29 g/ 162.2 g/mol

Moles = 0.16 g