Question

How much Copper nitrate, water, and sodium phospate is needed to make 2 grams of pigment.

Answer 1

By combining aqueous solution of copper nitrate and sodium phosphate, copper phosphate ( Cu₃(PO₄)₂) is precipitated

2Na₃PO₄ +3 Cu(NO₃)₂ Cu₃(PO₄)₂ + 6NaNO₃

2 moles of of sodium suphate reacts with 3 moles of copper nitrate to give 1 mole of precipitate

Number of moles in 2g of pigment (Cu₃(PO₄)₂) = mass given /molecular mass = 2 / 380.58 = 0.00525 moles

Moles of Sodium sulphate required = 2 x 0.00525 = 0.0105

Moles of copper nitrate required = 3 x 0.00525 = 0.01575

Now we can calculate mass of reactants required:

Mass of sodium phosphate = No. of moles x molecular mass = 0.0105 x 163.94 = 1.7213 g

Mass of copper nitrate = 0.01575 x 187.56 = 2.9540 g

Water is used as solvent.