Mixed 0.2 liters of 0.01 M calcium chloride solution and 0.5 liters of 0.02 M sodium carbonate

Mixed 0.2 liters of 0.01 M calcium chloride solution and 0.5 liters of 0.02 M sodium carbonate solution. Determine if a precipitate forms.

Given:
V solution (CaCl2) = 0.2 l
Cm (CaCl2) = 0.01 M
V solution (Na2CO3) = 0.5 l
Cm (Na2CO3) = 0.02 M

To find:
sediment -?

Decision:
1) CaCl2 + Na2CO3 => CaCO3 ↓ + 2NaCl;
2) PR (CaCO3) = 3.8 * 10-9;
3) [Ca2 +] 1 = Cm (CaCl2) = 0.01 M;
4) [CO32-] 1 = Cm (Na2CO3) = 0.02 M;
5) V solution = V solution (CaCl2) + V solution (Na2CO3) = 0.2 + 0.5 = 0.7 l;
6) [Ca2 +] 2 = Cm (CaCl2) * V solution (CaCl2) / V solution = 0.01 * 0.2 / 0.7 = 0.003 M;
7) [CO32-] 2 = Cm (Na2CO3) * V solution (Na2CO3) / V solution = 0.02 * 0.5 / 0.7 = 0.014 M;
8) PC = [Ca2 +] 2 * [CO32-] 2 = 0.003 * 0.014 = 0.000042 = 4.2 * 10-5;
9) PC> PR – a precipitate is formed.

Answer: A precipitate is formed.