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Sodium chloride percentage mass calculation
The total mass of dissolved solids in a 100 cm³ sample of sea water is 3.50 g.
The percentage of sodium chloride in the dissolved solids is 77.8%.
Calculate the mass of sodium chloride dissolved in the 100 cm³ sample of sea water.
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Marking points
- 1 Multiplies 3.50 g by 77.8/100.
- 2 Gives 2.72 g, with 2.723 g also accepted.
Full-mark answer
Mass of sodium chloride = (77.8 ÷ 100) × 3.50 g = 2.723 g, so the mass is 2.72 g.
Why this answer loses marks
Multiply the total mass by the percentage as a whole number.
A percentage must first become a fraction of the whole before it scales the total mass.