Question

Atomic mass of Na is 23 a.m.u
Calculate
1. number of moles in 400g of NA
2. number of atoms in 4.6 g of NA
3. mass of 3.01×1020 molecules of NA​

Answer 1

Explanation:

1. 23gm of Na = 1 mol

400 gm of Na = (1/23)×400

= 17.391 mol

2. No of atoms in 4.6 gm of Na

= (4.6/23)×Avagadro no

$= \frac{4.6}{23} \times 6.02 \times {10}^{23} = 1.204 \times {10}^{23}$

3.

$mass = \frac{3.01 \times {10}^{20} }{6.02 \times {10}^{23} } \times 23 \\ = 0.0115 \: gm$