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ICSE Class 10 Chemistry Question 20 of 23

Solved 2024 Specimen Paper ICSE Class 10 Chemistry — Question 19

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19
Question

Question 7(iii)

8.2 grams of calcium nitrate is decomposed by heating according to the equation

2Ca(NO3)2 ⟶ 2CaO + 4NO2 + O2

Calculate the following:

(a) Volume of nitrogen dioxide obtained at STP

(b) Mass of CaO formed

[Atomic weights: Ca –40 , N—14, O—16]

Answer

2Ca(NO3)2⟶2CaO+4NO2+O22[(40)+2(404[22.4]2(14+3(16))]+16) lit.=328 g=112g\begin{matrix} 2\text{Ca}(\text{NO}_3)_2 & \longrightarrow & 2\text{CaO} & + & 4\text{NO}_2 & + & \text{O}_2 \\ 2[(40) + & & 2(40 & & 4[22.4] \\ 2(14 +3(16))] & & + 16) & & \text{ lit.} \\ = 328 \text{ g} & & = 112 \text{g} \\ \end{matrix}

(i) 328 g of Ca(NO3)2 produces 4(22.4) lit of nitrogen dioxide.

∴ 8.2 g of Ca(NO3)2 will produce 4×22.4328\dfrac{4 \times 22.4}{328} x 8.2 = 2.24 lit of nitrogen dioxide.

Hence, vol of nitrogen dioxide evolved = 2.24 lit.

(ii) 328 g of Ca(NO3)2 produces 112 g of calcium oxide.

∴ 8.2 g of Ca(NO3)2 will produce 112328\dfrac{112}{328} x 8.2 = 2.8 g of calcium oxide.

Hence, 2.8 g of calcium oxide is produced.