Question

an air sample consists of 99.6% of nitrogen-14 and 0.4% of nitrogen-15. what is the average mass of nitrogen in this sample?

Answer 1

Answer:The average atomic mass of nitrogen is 14.004

Step-by-step explanation:

Abundance of nitrogen-14 = 99.6 %

Fractional abundance
`=(99.6)/(100)=0.996`

Abundance of nitrogen-15 = 0.4 %

Fractional abundance
`=(0.4)/(100)=0.004`

Average atomic mass of an element =

`\sum(\text{atomic mass of an isotopes}* (\text{fractional abundance}))`

Average atomic mass of nitrogen =

`14* 0.996+15* 0.004amu=14.004`

The approximate atomic mass of nitrogen is 14.004

Answer 2

The average mass of nitrogen is 14

calculation

step 1 : multiply each percentage by mass number

14 x 99.6 =1394

15 x 0.4 = 6

Step 2: add them up

1394 + 6 = 1400

step 3: Then divide by 100

= 1400/100 = 14