Question

In a chemical reaction, molecules of hydrogen gas (H2) react with molecules of oxygen gas (O2) in a sealed reaction chamber to produce water (H2O). This occurs through the following chemical equation. 2H2 + O2 → 2H2O What is conserved as the reaction occurs in the reaction chamber? A. temperature B. mass C. flammability D. molecule size

Answer 1

Option (B) is correct.

Step-by-step explanation:

Given that the molecules of hydrogen gas (
`H_2`) react with molecules of oxygen gas (
`O_2`) in a sealed reaction chamber to produce water (
`H_2O`).

The governing equation for the reaction is

`2H_2 +O_2 \rightarrow 2H_2O`

From the given, the only fact that can be observed that 2 moles of
`H_2` and 1 mole of
`O_2` reacts to produce 2 moles of
`H_2O`.

As the mass of 1 mole of
`H_2 = 2` grams ... (i)

The mass of 1 mole of
`O_2 = 32` grams ...(ii)

The mass of 1 mole of
`H_2O = 18` grams (iii)

Now, the mass of the reactant = Mass of 2 moles of
`H_2` + mass 1 mole of
`O_2`

`= 2 * 2 + 32` [ using equations (i) and (ii)]

`=4+32 = 36` grams.

Mass of the product = Mass of 2 moles of
`H_2O`

`=2* 18` [ using equations (iii)]

=36 grams

As the mass of reactants = mass of the product.

So, mass is conserved.

Hence, option (B) is correct.