Examine the samples given.
a) 20g He b) 44.8 L of `NH_3` at STP
c) 67.2 L `N_2` at STP d) 1 mole of `H_2 SO_4`
e) 180g of water
i) Arrange the samples in the increasing order of the number of molecules in each.
ii) What will be the ascending order of the number of atoms?
iii) What will be the mass of samples b,c, and d?

Explanation

a) 20g He
No of molecules present in it = `(20/4) xx 6.022 xx 10^23 = 5 xx 6.022 xx 10^23`
`= 5 xx 6.022 xx 10^23`
44.8 of `NH_3` at STP
No pf molecules present in it = `(44.8L/22.4L) = 2 = `2 xx 6.022 xx 10^23`
`NH_3 = 4 atom`
No of atoms present in it = `2 xx 6.022 xx 10^23`
`= 8 xx 6.022 xx 10^23`
GMM of ` NH_3` = 17g
`Mass of the gas = No. of moles xx GMM`
`= 2 xx 17 = 34g`
c) 67.2 of `N_2` at STP
NO of moles present in it = `(67.2L/22.4L) = 3`
`N_2 = 2 atoms`
No of molecules present in it
`= 3 xx 6.022 xx 10^23`
No of atoms present present in it
`= 3 xx 6.022 xx 10^23 xx 2`
`= 6 xx 6.022 xx 10^23 xx 2`
GMM of Na = 28g
` mass of the gas = No. of moles xx GMM`
`= 3 xx 28 = 84g`
d) ` 1 mole of H_2 SO_4`
No. of molecules present in it
`1 xx 6.022 xx 10^23`
` 6.022 xx 10^23`
`H_2 SO_4 = 7 atoms`
No of atoms present in it = `6.022 xx 10^23 xx 7`
Mass of 1 mole `H_2 SO_4`
`= (1 xx 2) + (32 xx 1) + (16 xx 4)`
`= 2 + 32 + 64 = 98g`
180g of water `(H_2 O)
No. of moles = `(180g/18g) = 10`
`H_2 O = 3 atoms`
no. of molecules =` 10 xx 6.022 xx 10^23 xx 3`
`= 30 xx 6.022 xx 10^23`
i) `H_2 SO_4 lt NH_3 lt N_2 lt He lt H_2 O`
ii) `He lt N_2 lt H_2 SO_4 lt NH_3 lt H_2 O `
iii) mass of b = 34 g
mass of c =n= 84 g
mass of d = 98 g