20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample ?

(At. Wt. : Mg = 24)

  • Option 1)

    75

  • Option 2)

    96

  • Option 3)

    60

  • Option 4)

    84

 

Answers (1)
V Vakul

As learnt in concept

Number of Moles -

No of moles = given mass of substance/ molar mass of substance

-

 

 MgCO_{3} \rightarrow MgO(s)+CO2(g)

supposed meals of = \frac{mass \:\:in\:\: grams}{molar \:\:mass}

 

 = \frac{20}{84} = 0.238 \:\:mal

By the stoichoimetry of the reaction alone, we know that 1 mal of the MgCO_{3} gives 1 mal of MgO moles of MgO obtained 

= \frac{8}{40} = 0.2 moles of MgO that should have been obtained in a pure sample = 0.238

\therefore moles of MgCO_{3} in the sample

= moles of MgO in the sample

= 0.2

\therefore % purity = \frac{0.2}{0.238} = 84\%

 


Option 1)

75

This solution is incorrect.

Option 2)

96

This solution is incorrect.

Option 3)

60

This solution is incorrect.

Option 4)

84

This solution is correct.

Preparation Products

Rank Booster NEET 2021

This course will help student to be better prepared and study in the right direction for NEET..

₹ 13999/- ₹ 9999/-
Buy Now
Knockout NEET May 2021

An exhaustive E-learning program for the complete preparation of NEET..

₹ 22999/- ₹ 14999/-
Buy Now
Knockout NEET May 2022

An exhaustive E-learning program for the complete preparation of NEET..

₹ 34999/- ₹ 24999/-
Buy Now
Test Series NEET May 2021

Take chapter-wise, subject-wise and Complete syllabus mock tests and get in depth analysis of your test..

₹ 6999/- ₹ 4999/-
Buy Now
Test Series NEET May 2022

Take chapter-wise, subject-wise and Complete syllabus mock tests and get an in-depth analysis of your test..

₹ 6999/-
Buy Now
Exams
Articles
Questions