Question

Given the reaction: 2H₂ + O₂ → 2H₂O The total number of grams of O₂ needed to produce 54 grams of water is _________.

Answer 1

Answer : The mass of
`O_2` needed are, 48 grams.

Explanation :

First we have to calculate the moles of
`H_2O`

`\text{Moles of }H_2O=\frac{\text{Given mass }H_2O}{\text{Molar mass }H_2O}=(54g)/(18g/mol)=3mol`

Now we have to calculate the moles of
`O_2`

The given balanced chemical reaction is:

`2H_2+O_2\rightarrow 2H_2O`

From the reaction, we conclude that

As, 2 mole of
`H_2O` produces from 1 mole of
`O_2`

So, 3 mole of
`H_2O` produces from
`(3)/(2)=1.5` mole of
`O_2`

Now we have to calculate the mass of
`O_2`

`\text{ Mass of }O_2=\text{ Moles of }O_2* \text{ Molar mass of }O_2`

Molar mass of
`O_2` = 32 g/mole

`\text{ Mass of }O_2=(1.5moles)* (32g/mole)=48g`

Therefore, the mass of
`O_2` needed are, 48 grams.