Question

How many grams are there in the following?
i. 2 moles of hydrogen molecule, H,
ii. 3 moles of chlorine molecule, Cl,
iii. 5 moles of sulphur molecule, Sg
iv. 4 moles of phosphorous molecule, P.​

Answer 1

i. 2 moles of hydrogen molecule :-

=> Number of moles = mass / molar mass

Therefore , number of moles is given = 2 mol

$\tt Molar \: mass \: of \: H_2 = 2$

=> 2 = mass / 2

=> 2×2 = mass

=> 4 grams = mass

ii. 3 moles of chlorine molecule :-

=> Number of moles = mass / molar mass

Therefore , number of moles is given = 3 mol

$\tt Molar \: mass \: of \: Cl_2 = 70$

( you can also take molar mass of chlorine molecule as 71 )

=> 3 = mass / 70

=> 3× 70 = mass

=> 210 grams = mass

iii. 5 moles of sulphur molecule :-

=> Number of moles = mass / molar mass

Therefore , number of moles is given = 5 mol

$\tt Molar \: mass \: of \: S_8 =256$

=> 5 = mass / 256

=> 5×256 = mass

=> 1280 grams = mass

iv. 4 moles of phosphorous molecule :-

=> Number of moles = mass/ molar mass

Therefore , number of moles is given = 4 mol

$\tt Molar \: mass \: of \: P_4 = 124$

=> 4 = mass / 124

=> 4× 124= mass

=> 496 grams = mass

Answer :

i. 4 grams

ii. 210 grams

iii. 1280 grams

iv. 496 grams