Question

Select from the list below the gas that matches the description given in each case and answer the
questions that follows: Ammonia,chlorine,hydrogen chloride,sulphur dioxide.
Gas B turns moist red litmus paper blue.
What is the name of Gas B?
Write the equation for the reaction that takes place when gas B is passed over heated copper oxide.

Answer 1

• Among the given gases, Ammonia$\left({\mathrm{NH}}_3\right)$ is basic in nature So it will turn the moist red litmus paper into the blue.
• So, gas B is Ammonia.
• When dry Gas B i.e. Ammonia$\left({\mathrm{NH}}_3\right)$ is passed over heated Copper oxide $\left(\mathrm{CuO}\right)$, it oxidizes the ${\mathrm{NH}}_3$ into Nitrogen$\left({\mathrm{N}}_2\right)$ and water vapor$\left({\mathrm{H}}_2\mathrm{O}\right)$ is formed. Also, $\mathrm{CuO}$ is reduced to copper$\left(\mathrm{Cu}\right)$.
• The reaction involved is:
  $2{\mathrm{NH}}_3\left(\mathrm{g}\right)+\underset{}{3\mathrm{CuO}\left(\mathrm{s}\right)\stackrel{∆}{\to }}\underset{}{3\mathrm{Cu}\left(\mathrm{s}\right)}+{\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$