Question

calculate the no. of particles (a) 24 g of 03 molecule . (b) 2 moles of zinc otom. (c ) 14 g of lithium atom (atomic mass of li= 7u)

Answer 1

a) weight of 03 = 24 g
molecular weight of o3 = 16 ×3 =48g
mole of 03 = weight / molecular weight
= 24 /48 = 1/2 mole
we know that one mole contains N atons
where N = 6.022 × 10 ^23
so 1/2 mole of o3 contain= 1/2 × N
= 3.011×10^23..
b) 1 mole of zinc atom contains =N particle
2 mole contains = 2N
= 2 × 6.022×10^23
= 12.044 × 10^23
c).weight of lithium = 14 g
atomic weight = 7 g
mole of lithium = 14/7 = 2 mole
1 mole of lithium = N particle
2 mole of lithium = 2N
= 2 × 6.022×10^23
=12.044×10^23

Answer 2

Number of particles: 
In 1 mole of any substance there is 6.023 × 10∧23 particles. You can use this conversion factor to convert from moles to number of particles

a) 24g of O3
mass = 24g 
molar mass = 16 × 3 = 48
find moles:
 moles = mass/molar mass
moles = 24/48
          = 0.5 moles
If 1 mole = 6.023 × 10∧23  particles
then 0.5 moles = 6.023×10∧23 ×0.5
                     
                        =  3.0115 × 10∧23 atoms of oxygen

b) 2 moles of zinc atom

Since 1 mole = 6.023 × 10∧23 particles
Then  2 moles = 6.023 × 10∧23 × 2 particles
                   
                         = 1.2046 × 10∧24 atoms of zinc

c) 14 g of lithium

moles = mass/ molar mass
          = 14/7
          = 2 moles
Since 1 mole = 6.023 × 10∧23 particles
Then  2 moles = 6.023 × 10∧23 × 2 particles
                   
                         = 1.2046 × 10∧24 atoms of lithium