Chemistry
(a) Calculate the number of moles in 7 g of nitrogen.
(b) What is the volume at S.T.P. of 7.1 g of chlorine?
(c) What is the mass of 56 cm3 of carbon monoxide at S.T.P?
Mole Concept
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Answer
(a) Gram molecular mass of N2 = 2 x 14 = 28 g
28 g of nitrogen = 1 mole
∴ 7 g of nitrogen = x 7
= 0.25 moles
(b) Gram molecular mass of Cl2 = 2 x 35.5 = 71 g
71 g of chlorine at S.T.P. occupies 22.4 litres
∴ 7.1 g of chlorine will occupy x 7.1
= 2.24 litre = 2.24 dm3
(c) Gram molecular mass of carbon monoxide (CO) = 12 + 16 = 28 g
28 g of carbon monoxide at S.T.P. occupies 22,400 cm3 volume
So, 22,400 cm3 volume have mass = 28 g
∴ 56 cm3 volume will have mass x 56 = 0.07 g
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