To prepare a dilute sodium carbonate solution, 580 g of water was added to 40 g

To prepare a dilute sodium carbonate solution, 580 g of water was added to 40 g of its 50% solution. What is the concentration of the solution?

1) Calculate the mass of the solute in 40 g of 50% sodium carbonate solution. the calculation is carried out according to the formula: W = (mr.v – wa / mr – pa) / 100%. We substitute the available data into the formula: 50% = (mr.v – va / 40) / 100. mr.v – va = 20g.
2) Find the mass of the solution after adding water: 580 + 40 = 620.
3) and finally, according to the formula presented in paragraph 1, we find the mass fraction of acid in the resulting solution: W = (20/620) * 100 = 3.2%.
The resulting solution has a percentage concentration of 3.2%.