Question

Compound A is used as a solvent in cough syrup.
a) Write the equation for the combustion of A.
b) when A is heated with concentrated sulphuric acid water is removed and gas B is formed.
c) Write the electron dot structure of B.
d) name the type of reaction B undergoes with hydrogen.

Answer 1

Hint: The compound that is used as a solvent in the cough syrup is an alcohol with 2 carbon atoms. Reaction with sulphuric acid yields alkene. The combustion of organic compounds forms carbon dioxide gas. The addition of hydrogen will occur in compound B.

Complete step by step answer:
The compound A is ethanol. It is used as a solvent in cough syrups. The molecular formula of ethanol is: \[{\text{C}}{{\text{H}}_3}{\text{C}}{{\text{H}}_2}{\text{OH}}\].
Let us study the product formed in each of the given statements,
a.Combustion refers to the heating of a compound in the presence of oxygen. When an organic compound undergoes complete combustion it forms carbon dioxide and water the reaction occurs as follow:
\[{\text{C}}{{\text{H}}_3}{\text{C}}{{\text{H}}_2}{\text{OH}} + 3{{\text{O}}_2} \to 2{\text{C}}{{\text{O}}_2} + 3{{\text{H}}_2}{\text{O}}\]
b.When alcohol is treated with concentrated sulphuric acid then dehydration of alcohol occurs. Dehydration refers to the removal of water from any molecule. Dehydration of alcohol yields alkene with the same number of carbon as in alcohol. So with 2 carbons ethene will form along with water molecules. Ethene is a gas at room temperature. The chemical reaction follows as:
\[{\text{C}}{{\text{H}}_3}{\text{C}}{{\text{H}}_2}{\text{OH}} + {{\text{H}}_2}{\text{S}}{{\text{O}}_4} \to {\text{C}}{{\text{H}}_2} = {\text{C}}{{\text{H}}_2}\]
c.The electron Dot structure is written by representing the valence electrons in the form of dots around the chemical symbol of the element. Structure of the compound Ethene formed can be written as:

d.When the compound B formed is treated with hydrogen, and then the hydrogen adds up into the double bond of ethene and ethane is formed, it undergoes hydrogenation reaction. The product formed is as follow:
\[{\text{C}}{{\text{H}}_2} = {\text{C}}{{\text{H}}_2} + {{\text{H}}_2} \to {\text{C}}{{\text{H}}_3} - {\text{C}}{{\text{H}}_3}\]

Note:
Ethanol has the ability to dissolve many active ingredients and act as a preservative. It is a very flammable liquid. To prevent the use of ethanol for drinking purposes, it is denatured by adding substances which are not suitable for human consumption.