Question

calculate the number of molecules in
0.1 mole of water
2) Calculate the number of atoms in 3 molecules of oxygen gas
b)0.01 moles of nitrogen gas

Answer 1

1) Molar mass of H₂O = 18 g mol^-1
1 mole of water = 6.022$\times$10²³ molecules
0.1 mole of water = $6.022\times {10}^{23}\times 0.1=6.022\times {10}^{22}molecules$

2) 1 molecule of oxygen contains = 6.022$\times$10²³ atoms
3 molecules of oxygen contains = $6.022\times {10}^{23}\times 3=18.066\times {10}^{23}atoms$

3) 1 mole of nitrogen gas (N₂) contains = 6.022$\times$10²³ atoms
0.01 mole of N₂ contains = $6.022\times {10}^{23}\times 0.01=6.022\times {10}^{21}atoms$