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#water mass

3 public questions tagged with this topic.

Vapour Pressure and Raoult's Law - Ideal and Non-ideal Solutions

The vapor pressure of pure water is 30 mm Hg at a certain temperature. A solution with a non-volatile solute has a vapor

(p⁰ - p/p⁰) = xsolute . (30 - 28.5/30) = 0.05 = (nsolute/nsolute + nwater) . Molality = (nsolute/wwater) = 0.5 . Assume wwater = 1 kg , then nsolute = 0.5 . nwater = (1000/18) ≈ 55.56 . xsolute = (0.5/0.5 + 55.56) ≈ 0.0089 , adjust wwater = (0.5 × 18/0.05) = 180 g .

Ref: NCERT Class 12 Chemistry > Chapter 1: Solutions > Topic: Vapour Pressure and Raoult's Law - Ideal and Non-ideal Solutions

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Dalton's Atomic Theory and Atomic and Molecular Masses

What is the mass of H₂O produced when 8 g of H₂ reacts with 32 g of O₂? (Atomic masses: H = 1, O = 16)

Reaction: 2 H₂ + O₂ → 2 H₂O. Moles: H₂ = 8/2 = 4 mol, O₂ = 32/32 = 1 mol. 2 mol H₂ need 1 mol O₂; 1 mol O₂ limits, reacts with 2 mol H₂. 2 mol H₂O formed = 2 × 18 = 36 g.

Ref: NCERT Class 11 Chemistry > Chapter 1: Some Basic Concepts of Chemistry > Topic: Dalton's Atomic Theory and Atomic and Molecular Masses

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