A solid mixture containing 4 moles of LiNO ₃ , 2 moles of NaNO ₃ , 2 moles of Li ₂ CO ₃ and 1 mole of Na ₂ CO ₃ is heated strongly to a constant weight. The total number of moles of gas(es) evolved is ________.

Step-by-step solution

Let us write the balanced thermal decomposition reactions for each compound in the mixture: 1. Lithium nitrate decomposes to give lithium oxide, nitrogen dioxide, and oxygen: 4 LiNO ₃ 2 Li ₂ O + 4 NO ₂ + O ₂ From 4 moles of LiNO ₃ , we get 4 moles of NO ₂ and 1 mole of O ₂ . Moles of gas from LiNO ₃ = 4 + 1 = 5 moles . 2. Sodium nitrate decomposes to give sodium nitrite and oxygen: 2 NaNO ₃ 2 NaNO ₂ + O ₂ From 2 moles of NaNO ₃ , we get 1 mole of O ₂ . Moles of gas from NaNO ₃ = 1 mole . 3. Lithium carbonate decomp