Question

calculate the number of particles in the following
a)69gof Na atoms
b)52g of He
c)0.1 mole of carbon

Answer 1

1) Molar mass of sodium atom = 23 g mol^-1
23 g of sodium contains = 6.022$\times$10²³ particles
69 g of sodium contains = $\frac{6.022\times {10}^{23}}{23}\times 69$ = 18.066$\times$10²³ particles

2) Molar mass of helium = 4 g mol^-1
4 g of He contains = 6.022$\times$10²³ particles
52 g of He contains = $\frac{6.022\times {10}^{23}}{4}\times 52$ = 78.28$\times$10³ particles

3) 1 mole of carbon contains = 6.022$\times$10²³ particles
0.1 mole = $6.022\times {10}^{23}\times 0.1$ = 6.022$\times$10²² particles