Chapter 3.4, Problem 22PP

Interpretation Introduction

Interpretation:

Whether the given compounds are same or not needs to be explained.

Concept introduction:

The mass percentage is defined as the percentage of component present in it. The mass percentage of the element is the mass of element divided by the total mass of the compound and multiplied by 100.

$\text{Mass percentage =}\frac{\text{mass}\text{of}\text{element}}{\text{mass}\text{of}\text{total}\text{compound}}\text{×100}$

Answer to Problem 22PP

The compounds are not same because their mass compositions are different.

Explanation of Solution

Given information:

The mass value of hydrogen for sample $\text{I}$ is $\text{15}\text{.0 g}$ and oxygen mass is $\text{120}\text{.0}\text{g}$.

The percentage by mass for sample I calculated as −

Compound mass for Sample $\text{I}\text{=15}\text{.0 g + 120}\text{.0 g =135}\text{.0 g}$

Percentage by mass for hydrogen $\text{= }\frac{\text{15}\text{.0 g}}{\text{15}\text{.0 g + 120}\text{.0 g}}\times \text{100}\text{=11}\text{.1\%}$

The mass value of hydrogen for sample $\text{II}$ is $\text{2}\text{.0}\text{g}$ and oxygen mass is $\text{32}\text{.0 g}$.

The percentage by mass for sample II calculated as −

Compound mass for Sample $\text{II}\text{= 2}\text{.0 g + 32}\text{.0 g = 34}\text{.0 g}$

Percentage by mass for hydrogen $\text{=}\frac{\text{2}\text{.0 g}}{\text{2}\text{.0 g + 32}\text{.0 g}}\times \text{100 = 5}\text{.9\%}$

The value of mass percentage value for a compound $\text{I}$ and compound $\text{II}$ is calculated which is different, so both compounds are different.

Conclusion

From the mass of an element and the mass of compound the percentage by mass of elements calculated in the formed compound. The percentage by mass of hydrogen for compounds $\text{I}$ and $\text{II}$ is different because the mass composition is different in both compounds. So, they are different from each other.