Calculate the mass percent (m/m) for the solute?

65 g of NaOH in 355 g of NaOH solution
%m/m = 65g/355g*100 = 18.3%m/m
Answer to 2 significant digits = 18%m/m

2.0 g of KOH and 25.0 g of H2O
Total mass of solution = 27.0g
%m/m = 2.0g/27.0g*100 = 7.4%m/m ( 2 significant digits)

48.5 g of Na2CO3 in 260.0 g of Na2CO3 solution
%m/m = 48.5g/260.0g*100 = 18.6%m/m ( 3 significant digits)

65 g of NaOH in 355 g of NaOH solution

Mass percent for the solute
= [(Mass of solute)/(Mass of solution)] × 100(%)
= (65/355) × 100(%)
= 18(%) (to 2 sig. fig.)


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2.0 g of KOH and 25.0 g of H₂O

Mass percent for the solute
= [(Mass of solute)/(Mass of solution)] × 100(%)
= [2.0/(2.0 + 25.0)] × 100(%)
= 7.4(%) (to 2 sig. fig.)


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48.5 g of Na₂CO₃ in 260.0 g of Na₂CO₃ solution

Mass percent for the solute
= [(Mass of solute)/(Mass of solution)] × 100(%)
= (48.5/260.0) × 100(%)
= 18.7(%) (to 3 sig. fig.)