3.88 g of a mixture of Na 2 CO 3 and CaCO 3 is heated to a constant mass of 3.00 g. What was the mass of Na 2 CO 3 (in grams) in the mixture?

Question

3.88 g of a mixture of Na 2 CO 3 and CaCO 3 is heated to a constant mass of 3.00 g. What was the mass of Na 2 CO 3 (in grams) in the mixture? (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

Na 2 CO 3 does not decompose on heating. CaCO 3 decomposes to form CaO and CO 2. CaCO 3 xrightarrowΔ CaO + CO 2 ∴ Loss in mass is due to loss of CO 2 gas ∴ (3.88-3.00=0.88 g ) of CO 2 is lost during heating. 0.88 g CO 2=(0.88/44)=0.02 mol CO 2 From the reaction stoichiometry, 0.02 mol CO 2 ≡ 0.02 mol CaCO 3 0.02 mol CaCO 3=0.02 × 100=2.00 g CaCO 3 ∴ Mass of Na 2 CO 3 in the mixture =3.88-2.00 g =1.88 g

Q. 3.88g of a mixture of Na2​CO3​ and CaCO3​ is heated to a constant mass of 3.00g. What was the mass of Na2​CO3​ (in grams) in the mixture?

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