One of these two substances is a liquid at room temperature and the other one is a gas. Which one is the liquid and why ?
Here, we are going to identify the substance that is liquid at room temperature.
Out of the two compounds given, ethanol(CH3CH2OH) is a liquid.
In case of ethanol(CH3CH2OH), hydrogen bonding(the attractive force which binds hydrogen atom of one molecule with the electronegative atom of another molecule) takes place between the partially positive hydrogen atom and the partially negative oxygen atom as shown below:
Due to the presence of hydrogen bonding, the bonds in ethanol are not easily broken and hence ethanol remains in liquid state.
On the other hand, this type of bonding is absent in case of dimethyl ether(CH3OCH3) and hence it is a gas at room temperature.