What is the approximate molality of a 98 percent by mass sulfuric acid solution?
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Answer and explanation
Correct answer: 500 mol kg−1
Take 100 g of solution as a basis. It contains 98 g H2SO4 and 2 g water. Since the molar mass of H2SO4 is 98 g mol−1, the acid amount is 1 mol. Water mass is 0.002 kg. Molality = moles of solute divided by kilograms of solvent = 1/0.002 = 500 mol kg−1. Molality uses solvent mass, not solution mass.
Frequently asked questions
What is the correct answer to this question?
500 mol kg−1
Why is this the correct answer?
Take 100 g of solution as a basis. It contains 98 g H2SO4 and 2 g water. Since the molar mass of H2SO4 is 98 g mol−1, the acid amount is 1 mol. Water mass is 0.002 kg. Molality = moles of solute divided by kilograms of solvent = 1/0.002 = 500 mol kg−1. Molality uses solvent mass, not solution mass.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Chapter 01: Solutions.
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