Question

Calculate the number of grams contained in each of the following number of moles. Report your answer with the appropriate number of significant figures.

a. 0.410 mol of NaCl (sodium chloride)
b. 4.80 mol of C2H4 (ethylene)

Answer 1

Mass in gram of NaCl = 23.96 g

Mass in gram of C2H4 = 134.64 g

Part 1.

Given data:

Moles of NaCl =0.42 mol

Molecular mass of NaCl = 58.44 g/mol

Mass in grams of NaCl = ?

Solution:

The formula of number of moles = Mass in grams / Molecular mass

For the mass in grams = Molecular mass × Number of moles

By putting the given values in second formula:

Mass in grams of NaCl = 58.44 × 0.41

= 23.96 g

So the sodium chloride is 0.42 molar it means its mass in gram is 23.96.

Part 2.

Given data:

Moles of C2H4 = 4.80 mol

Molecular mass of C2H4 = 28.05 g/mol

Mass in grams of C2H4 = ?

Solution:

The formula of number of moles = Mass in grams / Molecular mass

For the mass in grams = Molecular mass × Number of moles

By putting the given values in second formula:

Mass in grams of C2H4 = 28.05 × 4.8

= 134.64 g

So 134.64 grams of ethylene contains 4.8 mol of ethylene.

Answer 2

Answers:

a. 131.85 grams

b. 134.69 grams

To calculate the number of grams in the number of moles given for each compound, consider the formula:

Moles = No. of grams / molar mass

Therefore, to find the gram it will become:

No. of grams = moles x molar mass

a. 0.410 mol of NaCl (sodium chloride)

Molar mass of NaCl = (286.14 + 35.45) = 321.59

No. of grams = moles x molar mass

No. of grams = 0.410 x 321.59 = 131.85 grams

b. 4.80 mol of C2H4 (ethylene)

Molar mass of C2H4 = (12.01 x 2) + (1.01 x 4) = 28.06

No. of grams = moles x molar mass

No. of grams = 4.80 x 28.06 = 134.69 grams