For each of the following chemical reactions, calculate the mass of the underlined reactant that is required to produce 1.000 g of the underlined product. (a) Mg + 2 HCI → H2 + MgCl2, (b) 2 CuSO4 + 4KI → 2 Cul + I2 + 2 K2SO4, (c) NaBH 4 + 2H2O → NaBO2 + 4H2

To calculate the mass of the underlined reactant that is required to produce 1.000 g of the underlined product.

Explanation:

Mg + 2 HCI → H2 + MgCl2, here 1 mol of Mg gives 1 mol of H2

Given, no of mol of H2 = mass/molar mass = 1/2=0.5gmol

Therefore, 0.5 mol of H2 produced required 0.5mol of Mg

In mass value, molar mass off Mg = 24g/mol

m = 0.5mol x 24 g/mol = 12g

2 CuSO4 + 4KI → 2 Cul + I2 + 2 K2SO4, here 2 mol of CuSO4 gives 1 mol of I2

Given, MOLAR MASS OF I = 254g/mol

no of mol of I2 = mass/molar mass = 1/254=0.00394gmol

Therefore, 0.00394 mol of I2 produced required 0.00787mol of CuSO4

In mass value, molar mass of CuSO4 = 159.6g/mol

m = 0.00787mol x 159.6 g/mol = 1.257g

NaBH 4 + 2H2O → NaBO2 + 4H2, here 1 mol of NaBH 4 gives 4 mol of H2

Given, MOLAR MASS OF H2 = 2g/mol

no of mol of H2 = mass/molar mass = 1/2=0.5gmol

Therefore, 0.5 mol of H2 produced required 0.125mol of NaBH 4

In mass value, molar mass of NaBH 4 = 37.83g/mol

m = 0.125mol x 37.83 g/mol = 4.692g of NaBH 4