Question

Which law of chemical combination does this prove? Explain. Deduce the number of molecules of the following compounds in the given quantities. 32g oxygen, 90g water, 8.8g carbon di oxide, 7.1g chlorine.​

Answer 1

a. 32g of oxygen

Number of moles in O 2

=Mass of O 2 in grams

= 32

32

= 1mol

1 mole of O 2 contains 6.022×10 ^23

molecules

b. 90g of water

Number of moles in water

= Mass of water in grams

Molecular mass of water

= 90

18

=5 moles

5 moles of H2O contains 5×6.022×10^23 molecules

= 30.11×10 ^23 molecules

c. 8.8g of CO2

Number of moles in CO+2

= Mass of CO2 in grams

Molecular mass of CO2

= 8.8

44

=0.2mol

0.2 moles of CO2 contains 0.2×6.022×10^23molecules

=1.2044×10 ^23 molecules

d. 7.1g of chlorine

No. of moles in chlorine

= Mass of chlorine in grams

Molecular mass of chlorine

= 7.1

71

=0.1mol

0.1 moles of Cl2 contains 0.1×6.022×10^23

molecules

= 0.6022×10 ^23 molecules

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