Question

_____ grams of $3-\mathrm{Hydroxy}\mathrm{propanal}(\mathrm{MW}=74)$ must be dehydrated to produce $7.8\mathrm{g}$of acrolein $(\mathrm{MW}=56)\left({\mathrm{C}}_3{\mathrm{H}}_4\mathrm{O}\right)$ if the percentage yield is $64$.(Round off to the nearest integer)

(Given: Atomic masses : $\mathrm{C}:12.0\mathrm{u},\mathrm{H}:1.0\mathrm{u},\mathrm{O}:16.0\mathrm{u}$)

Answer 1

Answer:16

$$\begin{gathered} \mathrm{HO}-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{CHO} \\ \mathrm{xmol} \\ \downarrow -{\mathrm{H}}_2\mathrm{O} \\ {\mathrm{C}}_3{\mathrm{H}}_4\mathrm{O} \\ 7.8\mathrm{gm} \end{gathered}$$

$$\begin{gathered} 7.8/56=0.14\mathrm{mol} \\ \%\mathrm{yield}= \\ \frac{7.8/56}{\mathrm{x}}\times 100=64 \\ \mathrm{x}=\frac{7.8\times 100}{56\times 64}=\frac{780}{56\times 64}\mathrm{mol} \\ {\mathrm{W}}_{\mathrm{reactant}}=\frac{780}{56\times 64}\times 74 \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{=}\mathbf{16}\mathbf{.}\mathbf{11}\mathbf{g} \end{gathered}$$