Question

how many mL of 5% BaCl2 X(multiplied) 2H2O are needed for 0.3500g pure sodium sulfate?

Answer 1

5% BaCl2.2H2O means 5g of that material in 100 mL soln IF you mean 5% w/v. Convert 5g to moles. moles = grams/molar mass That will be moles/100 mL, multiply by 10 to obtain moles/L or molarity. Then
use this example to find moles BaCl2.2H2O needed.
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