Question

QuestionCommentsMax MarksAwarded Marks 1 An element forms two oxides. In one oxide, one gram of the oxide contains 0.5 g of element. In another oxide, 4 g of oxide contains 0.8 g of the element. Show that these data confirm the law of multiple proportion.​

Answer 1

What is the law of multiple proportions?

• The law of multiple proportions state that if 2 elements can combine to form 2 different compounds, then the masses of one element that combines with a fixed mass of the other element, will always be ratios of whole numbers.
• For example, let elements X and Y form two compounds A and B
• Then, $\frac{ratio\hspace{1 mm}of \hspace{1 mm}X \hspace{1 mm}to \hspace{1 mm}Y\hspace{1 mm} in \hspace{1 mm}compound \hspace{1 mm}A}{ratio \hspace{1 mm}of \hspace{1 mm}X\hspace{1 mm} to \hspace{1 mm}Y\hspace{1 mm} in \hspace{1 mm}compound \hspace{1 mm}B} = a\hspace{1 mm}whole\hspace{1 mm}number$

Given:

• 1 g of oxide A contains 0.5 g of element
• 4 g of oxide B contains 0.8 g of element

We can see that,

• For oxide A, % of element is $\frac{0.5}{1} =50\%=0.5$
• For oxide A, % of oxygen is $50 \%$. So ratio of element to oxygen is $1:1$
• For oxide B, % of element is $\frac{0.8}{4} =20\%=0.2$  
• For oxide B, % of oxygen is $80\%$. So ratio of element to oxygen is $1:4$

So it can be observed that ,

$\frac{ratio\hspace{1mm}of\hspace{1mm}element\hspace{1mm}to\hspace{1mm}oxygen\hspace{1mm}in\hspace{1mm}oxide\hspace{1mm}A}{ratio\hspace{1mm}of\hspace{1mm}element\hspace{1mm}to\hspace{1mm}oxygen\hspace{1mm}in\hspace{1mm}oxide\hspace{1mm}B}= \frac{1:1}{1:4}= 4$

As we can see, this ratio 4 is a whole number. So we can say that these data confirm the law of multiple proportion.​