How much water and salt do you need to take to prepare 250 g of 10% sodium nitrate solution?

To solve such problems, you need to use the formula for the mass fraction: the mass of the substance is divided by the mass of the solution and multiplied by 100%.
W = (mv-va / mr-ra) * 100%
1. Knowing the mass of the substance, we find the mass of the solution: 250 * 0.1 = 25g – of the pure substance.
2. To find the mass of water, subtract the mass of the substance from the total mass of the solution:
250-25 = 225g – H2O
Answer: 25g of salt; 225g water.