A sample of H2O2 labelled as 25% (w/w) has a density of 1.25g/mL. Which among the following correctly represents its concentration?
i. Molarity =9.2M
ii. Molality =9.8m
iii. % w/V =33.6%
iv. ppm (w/w) =2500ppm
A
i, ii
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B
i, ii, iii
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C
ii, iii, iv
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D
i, iii
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Solution
The correct option is A i, ii 25% (w/w) H2O2 = 25 g H2O2 in 100 g solution ⇒250 g H2O2 will be present in 1000 g solution
Volume of the solution=massdensity=10001.25=800mL
Molarity=No. of moles of soluteVolume of solution in L=25034×1000800=9.2M
Molality=No. of moles of soluteMass of solvent in kg=25034×1000750=9.8m