2-20 Calculate the percentage of hydrogen and oxygen in water, H2O, and hydrogen peroxide, H2O2.
Interpretation:
The percentage of hydrogen and oxygen in water,
Concept Introduction:
The same element combined together to form a chemical compound. The elements present in the compounds are in the fixed proportion by mass.
Answer to Problem 2.20P
H − 5.88%, O − 94.12% in hydrogen peroxide and H-11.11%, O-88.89% in water.
Explanation of Solution
The percentage of an element in a given compound is calculated using the mass of that element in the compound and the total mass of the compound.
A water molecule (H2 O) consists of two atoms of hydrogen and one atom of oxygen. The mass numbers of hydrogen and oxygen are 1 and 16 respectively.
Therefore, the mass of hydrogen in water is calculated using the mass number of hydrogen atoms in water.
Similarly, the mass of oxygen in water is calculated using the mass number of oxygen and the number of oxygen atoms in water.
Now, the total mass of water is calculated using the mass of hydrogen and the mass of oxygen.
Total mass of water = mass of hydrogen + mass of oxygen.
= 2 + 16.
= 18.
Now the percentage of oxygen and hydrogen in water are calculated as below:
So, it contains 11.11% hydrogen and 88.89% oxygen.
A hydrogen peroxide contains two hydrogen and two oxygen atoms. And their masses are 1 and 16 respectively.
So, the total masses of hydrogen and oxygen are as below:
Mass of hydrogen
Mass of oxygen
And total mass of H2 O2 = 32 + 2 = 34.
Now the calculation of percentage of hydrogen and oxygen in H2 O2
H − 5.88%, O − 94.12% in hydrogen peroxide and H-11.11%, O-88.89% in water.
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Chapter 2 Solutions
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