Calculate the mass of the precipitate formed by draining 200 g of 20% sodium hydroxide solution

Calculate the mass of the precipitate formed by draining 200 g of 20% sodium hydroxide solution with a solution containing an excess of copper sulfate (||).

Given:

m (p-pa NaOH) = 200 g;

w% (NaOH) = 20%;

To find:

m (draft) -?

Decision:

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

1) Find the mass of sodium hydroxide in the solution:

m (NaOH) = 200 g * 0.2 = 40 g;

2) Next, we find the amount of sodium hydroxide:

n (NaOH) = 40 g: 40 g / mol = 1 mol;

3) Find the amount of copper hydroxide. To do this, we compose a logical expression:

if 2 mol NaOH gives 1 mol Cu (OH) 2,

then 1 mole of NaOH will give x mole of Cu (OH) 2,

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

4) Now we can find the mass of copper hydroxide precipitated during the reaction:

m (Cu (OH) 2) = 0.5 mol * 98 g / mol = 49 g.

Answer: Cu (OH) 2 = 49 g.