To 160 g of a solution of potassium carbonate with a mass fraction of 5% was added 40 g of a solution

To 160 g of a solution of potassium carbonate with a mass fraction of 5% was added 40 g of a solution of the same salt with a mass fraction of 10%. The mass fraction of salt in the resulting solution is equal to ..

Given:

m (first solution) = 160 g

m (second solution) = 40 g

w% (first solution) = 5%

w% (second solution) = 10%

To find:

w% (in final solution) -?

Solution:

1) Find the mass of the total solution after draining:

m (solution) = 160 g + 40 g = 200 g;

2) Find the mass of salt in both solutions:

m1 (K2CO3) = 160 g * 0.05 = 8 g

m2 (K2CO3) = 40 g * 0.1 = 4 g

3) Find the mass of salt after draining the solutions:

m (K2CO3) = 8 g + 4 g = 12 g;

4) Find the mass fraction of potassium carbonate in the final solution:

w% (K2CO3) = m (K2CO3): m (solution) * 100% = 12 g: 200 g * 100% = 6%.

Answer: w% (K2CO3) = 6%.