Question

Calculate the number of moles of the indicated sub- stance in each of the following samples. a. 41.5 g of MgCl2 b. 135 mg of Li2O c. 1.21 kg of Cr d. 62.5 g of H2SO4 e. 42.7 g of C6H6 f. 135 g of H2O2

Answer 1

A: 0.436 moles MgCl2

B: 0.00452 moles Li2O

C: 23.3 moles Cr

D: 0.637 moles H2SO4

E: 0.547 moles C6H6

F: 3.97 moles H2O2

Step-by-step explanation:

A: Calculate the number of moles of 41.5 grams of MgCl2

Molar mass of MgCl2 = 95.21 g/mol

Moles MgCl2 = 41.5 grams / 95.21 g/mol = 0.436 moles

B: Calculate the number of moles of 135 mg of Li2O

Molar mass of Li2O = 29.88 g/mol

Moles Li2O = 0.135 grams / 29.88 g/mol = 0.00452 moles

C: Calculate the number of moles of 1.21 kg of Cr

Molar mass of Cr = 52.0 g/mol

Moles Cr = 1210 grams / 52.0 g/mol = 23.3 moles

D: Calculate the number of moles of 62.5 grams of H2SO4

Molar mass of H2SO4 = 98.08 g/mol

Moles H2SO4 = 62.5 grams / 98.08 g/mol = 0.637 moles

E: Calculate the number of moles of 42.7 grams of C6H6

Molar mass of C6H6 = 78.11 g/mol

Moles C6H6 = 42.7 grams / 78.11 g/mol = 0.547 moles

F: Calculate the number of moles of 135 grams of H2O2

Molar mass of H2O2 = 34.01 g/mol

Moles H2O2 = 135 grams / 34.01 g/mol = 3.97 moles