To 400 g of a 12-solution naoh, 100 g of water was added to determine the mass fraction

To 400 g of a 12-solution naoh, 100 g of water was added to determine the mass fraction of a solute in the resulting solution.

m (NaOH) = 400 g.
W (NaOH) = 12%.
m (H2O) = 100 g.
Determine the mass fraction of the substance in the solution. We write down the solution.
First, determine the mass of sodium hydroxide in the solution. We use the following formula.
W = m r.v. / m r-ra * 100%.
m = 400 * 0.12 = 48 g.
Next, we determine the total mass of the solution. We write down the solution.
m solution = m (H2O) + m (NaOH).
m solution = 100 + 400 = 500 g.
Next, we determine the mass fraction of sodium hydroxide in the resulting solution. We write down the resulting solution.
W = 48/500 * 100% = 9.6%.
Answer: W (NaOH) = 9.6%.