Question

Consider the following reaction sequence:

$S_8\left(s\right)+{80}_2\left(g\right)\to {8SO}_2\left(g\right)$

${2SO}_8\left(g\right)+O_2\left(g\right)\to {2SO}_3\left(g\right)$

How many grams of ${SO}_3$ are produced from $1$ mole ${SO}_8$?

• A. $1280g$
• B. $690g$
• C. $640g$
• D. $320g$

Answer 1

Answer: (C)

$640g$

${S_8}_{\left(s\right)}+8{O_2}_{\left(g\right)}⟶8{S{O}_2}_{\left(g\right)}$

As we have $1$ mole of $S_8$

According to reaction, one mole of $S{O}_2$ produces 8 mles of $S{O}_2$

Further,

$2{S{O}_8}_{\left(g\right)}+{O_2}_{\left(g\right)}⟶2{S{O}_3}_{\left(g\right)}$

As per the reaction,

No. of moles of $S{O}_3$ produced by $2$ moles of $S{O}_2=2\text{moles}$

$\therefore$ No. of moles of $S{O}_3$ produced by $8$ moles of $S{O}_2=8\text{moles}$

As we know that,

$\text{Wt. of compound}=\text{no. of moles}\times \text{molar mass}$

$\therefore$ Weight of $S{O}_3$ in 8 moles $=8\times 80=640g[\because \text{Molar mass of}S{O}_3=80g]$

Hence, $640$ grams of $S{O}_3$ are produced by $1$ mole of $S_8$.

The correct option is C.