Question

hydrogen and oxygen combine in the ratio of 1:8 by mass to form water what mass of water would be required to react completely with 4g of hydrogen and 34g of oxygen​

Answer 1

Answer:

Hydrogen and oxygen combine in the ratio of 1 : 8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas? Thus, 24 g of oxygen gas would be required to react completely with 3 g of hydrogen gas.

Answer 2

The law of constant proportions states that in a chemical substance, the elements are always present in definite proportions by mass. Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water.

1g of hydrogen reacts with oxygen = 8g

Thus, in order to form water, 3 x 8 = 24 g of oxygen will react completely with 3 g of hydrogen gas.

Concept insight: Recall the law of constant proportions and then apply that in a chemical substance, the elements are always present in definite proportions by mass.

OR

$2H_{2} + O_{2}→2H_{2}O$

$4g \: \: \: 32g \: \: \: 36g$

Since, 32 g of oxygen reacts with 4g of H2.

So, 3g of H2 will require =

$\frac{3 \times 32}{4} = 24grams \: \: of \: \: O_2$