Question

The ratio of the molecular weight of Hydrogen and Oxygen in water is 1: 8. Find the quantity of Hydrogen if Oxygen is 12 grams and the quantity of oxygen if hydrogen $\dfrac{3}{2}$ gms.

Answer 1

Hint: To solve this question, we need to assume the quantities of hydrogen and oxygen. Then we need to equate them with the relation that is developed on the basis of the molecular weight that is mentioned.

Complete step-by-step answer:
At first let us assume two variables for representing the quantities of hydrogen and oxygen, as mentioned in the question.
So, let x be the variable representing the quantity of hydrogen and y be the variable representing the quantity of oxygen.
Since the ratio of the molecular weight of hydrogen and oxygen in water is 1:8, as it is given, we can write the following:
y = 8x
It is given in the question that oxygen is 12 grams, therefore we can find the value of x, by putting the value of y in the equation derived above.
So, 12 = 8x
Therefore, x = $\dfrac{12}{8}$
So, the value of x is 1.5 grams.
As x represents hydrogen we can say, the quantity of hydrogen is 1.5 grams.
Now, moving on to the second part of the question. It is mentioned that hydrogen is $\dfrac{3}{2}$ grams.
So, in this case the value of x = $\dfrac{3}{2}$
Therefore, the value of y = $\dfrac{3}{2}\times 8$
So, the value of y is 12 grams. And y represents the quantity of oxygen. So, the quantity of oxygen is 12 grams.
So the final answer is, the quantity of hydrogen is 1.5 grams when the amount of oxygen is 12 grams. Similarly, the value of oxygen is 12 grams when the value of hydrogen is $\dfrac{3}{2}$ grams.

Note: We should be having an idea about the concept of molecular weight. By molecular weight we mean, the measure of the sum of the atomic weight values of the atoms, in a molecule. Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element.