A 75.0 sample of 1.50×10^−2 Na2SO4 is added to 75.0 mL of 1.26×10−2 Ca(NO3)2. What is the % Ca undissolved
Na2SO4 + Ca(NO3)2 ==> CaSO4(s) +2NaNO3
millimols Na2SO4 = mL x M = 1.125
millimols Ca(NO3)2 = 0.945.
I don't know what % Ca undissolved means? and % of what?
It will form 0.000945 mols CaSO4 solid
To calculate the percentage of Ca undissolved, we need to determine the amount of Ca that does dissolve and the total amount of Ca present in the initial solution.
First, let's calculate the amount of Ca that dissolves.
Given:
Volume of Ca(NO3)2 solution = 75.0 mL
Concentration of Ca(NO3)2 = 1.26x10^(-2) mol/L
To find the amount of Ca that dissolves, we use the formula:
Amount of Ca dissolved = Concentration of Ca(NO3)2 x Volume of Ca(NO3)2 solution
Amount of Ca dissolved = (1.26x10^(-2) mol/L) x (75.0 mL / 1000 mL/L)
Amount of Ca dissolved = 0.00945 mol
Now, let's determine the total amount of Ca in the initial solution.
Given:
Mass of Na2SO4 = 75.0 g
Molar mass of Na2SO4 = 22.99 g/mol + 32.07 g/mol + (4 x 16.00 g/mol) = 142.04 g/mol
Moles of Na2SO4 = Mass / Molar mass
Moles of Na2SO4 = 75.0 g / 142.04 g/mol
Moles of Na2SO4 = 0.528 mol
Since the Na2SO4 dissociates into two Na+ ions and one SO4^2- ion, the number of moles of Ca ions present is the same as the number of moles of Na2SO4.
Moles of Ca = Moles of Na2SO4 = 0.528 mol
Finally, we can calculate the percentage of Ca undissolved:
% Ca undissolved = (Amount of Ca undissolved / Total amount of Ca) x 100
Amount of Ca undissolved = Total amount of Ca - Amount of Ca dissolved
Amount of Ca undissolved = 0.528 mol - 0.00945 mol
Amount of Ca undissolved = 0.51855 mol
Total amount of Ca = Moles of Ca = 0.528 mol
% Ca undissolved = (0.51855 mol / 0.528 mol) x 100
% Ca undissolved ≈ 98.06%
Therefore, the percentage of Ca undissolved in the solution is approximately 98.06%.