Question

C-12 and c-13 are naturally occurring isotopes of the element carbon. c-12 occurs 98.89% of the time and c-13 occurs 1.108% of the time. what calculation should be used to determine the atomic mass of this element?

Answer 1

w₁(¹²C)=0.9889 (98.89%)
w₂(¹³C)=0.01108 (1.108%)
A(¹²C)=12
A(¹³C)=13

A(C)=w₁A(¹²C)+w₂A(¹³C)

A(C)=0.9889*12+0.01108*13=12.01084 a.m.u.

Answer 2

Answer:

We will determine the weighted average of the atomic mass of two isotopes.

Explanation:

The atomic mass of an element is the weighted average of atomic masses of the most abundant isotopes occur in nature.

Given:

Percentage abundance of C-12 : 98.89%

Percentage abundance of C-13: 1.108%

The atomic mass of carbon will be"

$atomicmass=\frac{percentageofC12Xatomicmass+percentageofC13Xatomicmass}{100}$

Atomic mass = $\frac{98.89X12+1.108X13}{100}=12.101$g/mol