Question

Moles/Mass/Molecules Practice Problem Worksheet

Answer 1

Answer:

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