Question

Which two solutions have similar solubilities at 40°C? Na2SO4 and NaCl Na2HAsO4 and NaCl Na2HAsO4 and Na2SO4 Ba(NO3)2 and Ce2(SO4)3 • 9H2O

Answer 1

Answer is: Na₂HAsO₄ and Na₂SO₄.

1) Solubility of NaCl (sodium chloride) at 40°C is 36.3 grams.

2) Solubility of Na₂SO₄ (sodium sulfate) at 40°C is 48.8 grams.

3) Solubility of Na₂HAsO₄ (sodium arsenate dibasic) at 40°C is 48.9 grams.

4) Solubility of Ba(NO₃)₂ (barium nitrate) at 40°C is 14.1 grams.

5) Solubility of Ce₂(SO₄)₃·9H₂O (ceasium sulfate nonahydrate) at 40°C is 6.2 grams.

Answer 2

The correct answer is option C i.e. Na2HAsO4 and Na2SO4 Ba(NO3)2 

Refer to the graph attached below which shows how the solubility of a mixture changes with temperature variation.

As you can see in the graph at 40 °C, both Na2HAsO4 and Na2SO4 Ba(NO3)2  have same solubility coefficients. Thus, the answer is Na2HAsO4 and Na2SO4 Ba(NO3)2