Calculate the mass of the precipitate obtained by the interaction of 20 g of sodium hydroxide and copper sulfate.

Given:

m (NaOH) = 20 g;

To find:

m (draft) -?

Decision:

2NaOH + CuSO4 = Na2SO4 + Cu (OH) 2, – we solve the problem using the obtained reaction equation:

1) Find the amount of sodium hydroxide contained in 20 grams of the substance:

n (NaOH) = m: M = 20 g: 40 g / mol = 0.5 mol;

2) Next, find the amount of copper hydroxide. To do this, we compose a logical expression:

if 2 mol of NaOH gives 1 mol of Cu (OH) 2 in the reaction,

then 0.5 mol of NaOH will give a mol of Cu (OH) 2 in the reaction x,

then x = 0.5 mol * 1 mol: 2 mol = 0.25 mol.

3) Now we can find the mass of copper hydroxide precipitated as a result of the reaction:

m (Cu (OH) 2) = n * M = 0.25 mol * 98 g / mol = 24.5 g.

Answer: m (Cu (OH) 2) = 24.5 g.