Question

How many grams of hydrogen gas are needed to react with 5 moles of oxygen gas?

Thanks for the help :)

Answer 1

Please see processes below;

Explanation:

`H_(2(g)) -> 5O_(2(g)) rArr "Interpreted Equation"`

We are looking for the mass of `H_(2(g))`

Recall `"no of moles" = "mass"/"molar mass"`

`"no of moles of" color(white)x O_(2(g)) = 5mols`

`"molar mass of" color(white)x O_(2(g)) = 16gmol^-1`

`5 = "mass"/16`

Cross multiply..

`"mass" = 5 xx 16`

`"mass" =80g color(white)x "of" color(white)x O_(2(g))`

From the initial equation..

`H_(2(g)) -> 5O_(2(g))`

Since `1mol color(white)x "of" color(white)x H_(2(g))` is needed to react with `5mols color(white)x "of" color(white)x O_(2(g))`

`:. xmols color(white)x of color(white)x H_(2(g))` will react with `80g color(white)x "of" color(white)x O_(2(g))`

`rArr 1/x = 5/80`

Cross multiplying..

`80 xx 1 = 5 xx x`

`80 = 5x`

Divide both sides by `5`

`80/5 = (5x)/5`

`80/5 = (cancel5x)/cancel5`

`80/5 = x`

`16 = x`

Therefore;

`"mass" =16g color(white)x "of" color(white)x H_(2(g))`

`16g color(white)x "of" color(white)x H_(2(g))` is needed to react with `5mols color(white)x "of" color(white)x O_(2(g))`