Question

How many aluminium ions are present in $0.051g$ of aluminium oxide?

• A. $6.02\times {10}^{20}ions$
• B. $11.4\times {10}^{20}ions$
• C. $6.02\times {10}^{23}ions$
• D. $11.4\times {10}^{23}ions$

Answer 1

The correct option is A $6.02\times {10}^{20}ions$

Molar mass of $A{l}_2{O}_3=102g$
$102gA{l}_2{O}_3\to 2\times 6.02\times {10}^{23}A{l}^{3+}ions$
$\therefore 0.051gA{l}_2{O}_3\to \frac{2\times 6.02\times {10}^{23}\times 0.051}{102}A{l}^{3+}ions$
$=0.001\times 6.02\times {10}^{23}ions$
$=6.02\times {10}^{20}ions$