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Question
What is the concentration of sugar (C12H22O11) in mol L–1 if its 20 g are dissolved in enough water to make a final volume up to 2 L?
Solution
Molarity (M) of a solution is given by,
`="Number of moles of solute"/"Volume of solution in Litres"`
`="Mass of sugar/molar mass of sugar"/(2 "L")`
`=(20 "g"//[(12xx12)+(1xx22)+(11xx16)]"g")/(2"L")`
`=(20 "g"//342 "g")/(2"L")`
`=(0.0585" mol")/(2"L")`
= 0.02925 mol L-1
∴ Molar concentration of sugar = 0.02925 mol L–1
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