Chemistry numerical

[ashwinkandel]

What mass of solid residue can be obtained from the thermal decomposition of 4.10 g of
anhydrous calcium nitrate?
A 0.70 g B 1.00 g C 1.40 g D 2.25 g

my friend asked me this question. i said D but he said C is the answer given in marking scheme. Can someone tell me why and how?

[Deadly_king]

What mass of solid residue can be obtained from the thermal decomposition of 4.10 g of
anhydrous calcium nitrate?
A 0.70 g B 1.00 g C 1.40 g D 2.25 g

my friend asked me this question. i said D but he said C is the answer given in marking scheme. Can someone tell me why and how?

I guess I already answered that  

Anyway here it is once more :
First you need to write the equation of the decomposition of the nitrate which will be :
Ca(NO₃)₂ ---> CaO + NO₂
NO₂ will escape as it is a gas. Residue will consist of CaO only.

Mr Of Ca(NO₃)₂ = 164.1
Mr of CaO = 56.1
From equation :
1 mole of Calcium nitrate produces one mole pf CaO
Hence 164.1g of Ca(NO₃)₂ produces 56.1g of CaO
Therefore 4.1g of Ca(NO₃)₂ will produce (56.1/164.1)*4.1 = 1.40g

Hence answer is C

[ashwinkandel]

thanks deadly_king +rep

[Deadly_king]

thanks deadly_king +rep

Anytime dude