Question

How many grams of h2 would be needed to form 120g of h20? 2h2+o2-2h2o

Answer 1

Answer:

13.33g

Explanation:

molecular Mass of water M$_{r}$($H_{2} O$) → 18

Mass of water required m($H_{2} O$) → 120g

ⁿ (no of moles)= $\frac{m}{M_{r} }$

                     ⁿ = $\frac{120}{18}$

Water in moles is $\frac{20}{3}$ moles.

Chemical formulae:

$2H_{2} + O_{2}$ → 2$H_{2} O$

Balancing,

$H_{2} + \frac{1}{2} O_{2}$ → $H_{2} O$

we can see from the equation that one mole of hydrogen is also required to make one mole of water

molecular Mass of hydrogen M$_{r_{H_{2}} }$ → 2

ⁿ$_{H_{2} }$ = $\frac{20}{3}$

ⁿ$_{H_{2} }$ = $\frac{m}{M_{r} }$

$\frac{20}{3}$ = $\frac{m}{2} }$

m = $\frac{40}{3}$g

Hence to make 120g of water $\frac{40}{3}$g or 13.33g of water is required.