What is the purpose of adding sulphuric acid to the aspirin reaction mixture?

Making aspirin In this case just a few drops of sulphuric acid added to the mixture means that there are some free positive hydrogen ions in the solution which can bind to the ethanoic anhydride. This makes it more active and speeds up the reaction. To ensure the reaction goes as quickly as possible we have to heat it.Concentrated phosphoric acid will be used to keep everything in the acidified, protonated state. Acetic anhydride is the preferred acid derivative to synthesize aspirin commercially because the acetic acid produced in this reaction can be used again, by converting it back into acetic anhydride

Explanation:

the transfer of heat by electromagnetic radiation is called thermal radiation . it is usually carried out by electromagnetic waves in an energy range just below the visible spectrum, which is the infrared range.

so the answer would be radiation.

: )