The mass of a 30% baking soda solution is 700 g how many grams of water you need to add to get a 20% solution.

From the outset, you should determine how much baking soda your stock solution contains. T. to. its mass is 700 g, and the% of soda content in it is 30%, then the soda in it:

m = 700 * 30% = 700 * 0.3 = 210 (g).

Therefore, when we add water to this solution, the same 210 g of baking soda should make up 20% of the total mass of the solution. Then the new mass of the solution will be equal to:

M = 210: 20% = 210: 0.2 = 210 * 10/2 = 210 * 5 = 1050 (g).

Then add to the solution:

1050 – 700 = 350 (g).

Answer: 350 g of water.