Question

To four significant figures, determine the percent by mass H2O in CuSO4·12 H2O ___ % H2O?

Answer 1

Answer 2

To determine the percent by mass of H2O in CuSO4·12H2O, we need to calculate the molar mass of H2O and CuSO4·12H2O and then find the ratio.

The molar mass of H2O is calculated as follows: H: 2.016 g/mol (hydrogen atomic mass) O: 15.999 g/mol (oxygen atomic mass) Total molar mass of H2O = 2.016 g/mol + 15.999 g/mol = 18.015 g/mol

The molar mass of CuSO4·12H2O is calculated as follows: Cu: 63.546 g/mol (copper atomic mass) S: 32.07 g/mol (sulfur atomic mass) O: 15.999 g/mol (oxygen atomic mass) H: 1.008 g/mol (hydrogen atomic mass) Total molar mass of CuSO4·12H2O = 63.546 g/mol + 32.07 g/mol + (15.999 g/mol × 4) + (18.015 g/mol × 12) = 249.685 g/mol

To find the percent by mass of H2O, we divide the molar mass of H2O by the molar mass of CuSO4·12H2O and multiply by 100:

Percent by mass H2O = (18.015 g/mol / 249.685 g/mol) × 100 = 7.21%

Therefore, the percent by mass of H2O in CuSO4·12H2O is approximately 7.21%.