Percentage by mass of water in CuSO4.5H20 is 36.07% .
In this problem we have - copper(II) sulfate pentahydrate and it's molecular formula is (CuSO₄.5H₂O) .
There are 5 molecules of water are present.
Now we calculate it's molar mass-
We know that-
molar mass of Cu = 63.5u
Molar mass of SO₄ = 96 u
Molar mass of H₂O = 18 u
Now, molar mass of (CuSO₄.5H₂O) = 63.5 + 96 + 5 × 18
Now, molar mass of (CuSO₄.5H₂O) = 249.5u
And mass of water in CuSO₄.5H₂O = 90 u
now mass percentage of water = mass of water ÷ Total mass ×100
now mass percentage of water = 90 ÷ 249.5 × 100
now mass percentage of water = 36.07 %
So we find out mass percent by dividing given mass with total mass and then multiplying it with hundred and it came out to be 36.07 % .
Learn more about mass percent here: https://brainly.com/question/13896694
#SPJ10