Chemistry
(a) Calculate the percentage of sodium in sodium aluminium fluoride (Na3AlF6) correct to the nearest whole number.
(F = 19; Na =23; Al = 27)
(b) 560 ml of carbon monoxide is mixed with 500 ml of oxygen and ignited. The chemical equation for the reaction is as follows:
2CO + O2 ⟶ 2CO2
Calculate the volume of oxygen used and carbon dioxide formed in the above reaction.
Mole Concept
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Answer
Molecular weight of sodium aluminium fluoride (Na3AlF6)
= 3(23) + 27 + 6(19)
= 69 + 27 + 114
= 210 g
210 g of sodium aluminium fluoride contains 69 g of Na
∴ 100 g of sodium aluminium fluoride will contain = x 100 = 32.85% = 33%
Hence, percentage of sodium in sodium aluminium fluoride (Na3AlF6) is 33%
(b)
1 mole of O2 has volume = 22400 ml
Volume of oxygen used by 2 × 22400 ml CO = 22400 ml
∴ Vol. of O2 used by 560 ml CO
= x 560
= 280 ml
Volume of CO2 formed by 2 × 22400 ml CO = 2 x 22400 ml
∴ Vol. of CO2 formed by by 560 ml CO
= 560 ml
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