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Question

On burning sulfur in oxygen, sulfur dioxide is produced

S + O2 → SO2

For producing 2240 L of SO2 at STP

(i) How many grams of sulfur and (ii) how many moles of O2 will be required? (0 = 16, S = 32) [3]

OR

On burning 480 g of a solid compound in 352 g of oxygen, 320 g of another solid compound and a gaseous compound are produced. If the vapour density of the gaseous compound is 32, how many moles of the gaseous compound are formed? [3]

WBBSE Class X Physical Science Chemical Calculations 03 Mark 2023

Answer

Balanced Chemical Equation:

S        +      O2 →     SO2

32 g         1 mol       22.4 L

(i) Amount of S required to produce 22.4 L of SO2 = 32 g

⇒ Amount of S required to produce 2240 L of SO2 = 32\over 22.4 × 2240 = 3200 g

(ii) The number of moles of oxygen required to produce 22.4 L of SO2 = 1

⇒ The number of moles of oxygen required to produce 2240 L of SO2 = 1\over 22.4 × 2240 = 100 mol

OR

Given Data

  • Mass of solid compound burned = 480 g
  • Mass of oxygen used = 352 g
  • Mass of solid compound produced = 320 g
  • Vapor density of gaseous compound = 32

Molar Mass = 2 × Vapor Density

= 2 × 32

= 64

Mass of gaseous compound=480 g + 352 g − 320 g

= 512 g

∴ Moles of gaseous compound = 512/64 = 8 mol

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