The mass of table salt, which must be added to 70 g of a 2% NaCl solution to obtain a 6% solution, is …
September 20, 2021 | education
| 1. Let’s calculate the mass of sodium chloride in the first solution:
m1 (NaCl) = w1 (NaCl) * m1 (solution);
m1 (NaCl) = 0.02 * 70 = 1.4 g
2.Let x = the mass of the added salt, then the mass of the resulting solution:
m2 (solution) = m1 (solution) + x = 70 + x;
3.express the total mass of salt:
m2 (NaCl) = m1 (NaCl) + x = 1.4 + x;
4.we write down the expression for calculating the mass fraction:
w2 (NaCl) = m2 (NaCl): m2 (solution);
5. find the mass of added chloride – x:
0.06 = (1.4 + x): (70 + x);
(70 + x) * 0.06 = 1.4 + x;
2.8 = 0.94x
x = 2.98, that is, m2 (NaCl) = 2.98 g.
Answer: 2.98 g.
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