After 20.0g of Na2SO4 is added to a 0.5L saturated solution of CaSO4, does the concentration of Ca2+ increase, decrease, or stay the same? Assume that the overall volume of the solution does not change.
.......CaSO4 --> Ca^2+ + SO4^2-
I......solid......0.......0
C......solid......x.......x
E......solid......x.......x
Ksp CaSO4 = (Ca^2+)(SO4^2-)
Now if we add a large excess of sulfate as Na2SO4, that makes SO4^2- very large, Le Chatelier's Principle says the reaction has too much sulfate so the reaction shifts to the left. That decreases (Ca^2+).
To determine whether the concentration of Ca2+ increases, decreases, or stays the same after adding Na2SO4 to a saturated solution of CaSO4, we need to consider the following steps:
Step 1: Write the balanced equation for the reaction that occurs between Na2SO4 and CaSO4:
Na2SO4 + CaSO4 -> 2Na+ + Ca2+ + 2SO42-
Step 2: Verify the stoichiometry of the reaction:
From the balanced equation, we can see that for every mole of Na2SO4, one mole of Ca2+ is produced.
Step 3: Calculate the moles of Na2SO4:
To determine the moles of Na2SO4, we can use the formula:
moles = mass / molar mass
The molar mass of Na2SO4 is:
2(22.99 g/mol) + 1(32.07 g/mol) + 4(16.00 g/mol) = 142.04 g/mol
Therefore, the moles of Na2SO4 are:
moles = 20.0 g / 142.04 g/mol = 0.1409 mol
Step 4: Determine the change in concentration of Ca2+:
Since the overall volume of the solution does not change, the concentration of Ca2+ is affected by whether the additional Ca2+ ions from the reaction with Na2SO4 will cause precipitation or remain dissolved.
If the additional Ca2+ ions cause precipitation, then the concentration of Ca2+ will decrease. If the additional Ca2+ ions remain dissolved, then the concentration of Ca2+ will stay the same.
Step 5: Evaluate the solubility of CaSO4:
CaSO4 is sparingly soluble in water, and its solubility can be exceeded by adding more Ca2+ ions to the solution. As a result, the additional Ca2+ ions from the reaction with Na2SO4 will likely remain dissolved rather than precipitate.
Therefore, the concentration of Ca2+ will stay the same after adding 20.0g of Na2SO4 to the saturated solution of CaSO4, assuming that the overall volume of the solution does not change.
To determine whether the concentration of Ca2+ increases, decreases, or stays the same after adding 20.0g of Na2SO4 to a 0.5L saturated solution of CaSO4, you need to consider the chemical reaction that occurs when the two compounds are mixed.
Na2SO4 dissociates into two Na+ ions and one SO4^2- ion:
Na2SO4 --> 2Na+ + SO4^2-
CaSO4 dissociates into one Ca2+ ion and one SO4^2- ion:
CaSO4 --> Ca2+ + SO4^2-
When you add Na2SO4 to the solution of CaSO4, the SO4^2- ions from both compounds remain in solution. The Na+ ions from Na2SO4 will not interfere with the concentration of Ca2+.
Since the concentration of Ca2+ is determined solely by the concentration of CaSO4 in the saturated solution, the addition of Na2SO4 does not directly affect the concentration of Ca2+. Therefore, the concentration of Ca2+ will stay the same after adding 20.0g of Na2SO4 to the solution.