Question

reactant is needed to form the most amount
of product possible. mole ratios are useful for
chemists who need to be able to predict how
much product can be made using a given
amount of reactant.
to highlight this skill, lets use the reaction
weve discussed earlier - the combustion of
hydrogen gas.
if you had 0.35 moles of
hydrogen gas (h₂), how many
moles of product (h₂o) would
you expect (assuming there is
enough of the other reactant)?
how many moles of o₂ is needed
to react completely with 0.35
moles of h₂?

Explanation:

Step1: Write the balanced chemical equation

The combustion of hydrogen gas is \(2H_{2}+O_{2}
ightarrow 2H_{2}O\)

Step2: Calculate moles of \(H_{2}O\)

From the balanced equation, the mole ratio of \(H_{2}\) to \(H_{2}O\) is \(2:2 = 1:1\).
If \(n(H_{2})=0.35\space mol\), then \(n(H_{2}O)=\frac{2\space mol\space H_{2}O}{2\space mol\space H_{2}}\times0.35\space mol\space H_{2}= 0.35\space mol\)

Step3: Calculate moles of \(O_{2}\)

From the balanced equation, the mole ratio of \(H_{2}\) to \(O_{2}\) is \(2:1\)
\(n(O_{2})=\frac{1\space mol\space O_{2}}{2\space mol\space H_{2}}\times0.35\space mol\space H_{2}=0.175\space mol\)

Answer:

The number of moles of \(H_{2}O\) is \(0.35\space mol\) and the number of moles of \(O_{2}\) is \(0.175\space mol\)