Hydrochloric acid and sulfuric acid are both strong acids and as such do not react to yield a very different product. Following is the balanced chemical reaction for the given scenario:
`H_2SO_4 (aq) + HCl (aq) -> H_2SO_4 (aq) + HCl (g)`
The reactants and products are still the same (hydrochloric acid and sulfuric acid), the only difference is the phase change of hydrochloric acid, from an aqueous solution to the gas phase.
Generally, when we add dilute hydrochloric acid to a strong (or concentrated) solution of sulfuric acid, a dehydration reaction takes place. In this reaction, the sulfuric acid strips the hydrochloric acid of its water, effectively converting it to hydrochloric acid gas. Thus, when you carry out this reaction, you will see a lot of gas being produced. It is strongly suggested that you carry out such reactions in a fume hood and ensure your safety by using personal protective equipment.
Hope this helps.