Lessons

Eamcet Chemistry
1st Year : Unit 1.4 (Basics & Concepts) - Stoichiometric Calculations

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Q.

6 grams of magnesite mineral on heating liberated carbondioxide which measures 1.12 L at STP.The percentage purity of mineral is

View Answer

Correct choice: C

Explanation:

magnesite is magnesium carbonate. On heating it liberates carbondioxide.
MgCO3 →MgO + CO2
1 mole of CO2 is given by 1 mole of MgCO3
22.4 L of CO2 at STP is given by 84 grams of MgCO3
1.12 L of CO2 at STP = ?
The weight of pure MgCO3 to be decomposed =(1.12 × 84/22.4) = 4.2 grams
6 grams mineral has 4.2 grams MgCO3
Percent purity = × 100 = 70%
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