Why does he temperature of the conical flask change when zinc granules react with dilute sulphuric / hydrochloric acid?
Answers
Answer:
Explanation:
Zinc being an active metal readily reacts with dil. hydrochloric acid at room temperature to form soluble zinc chloride and hydrogen. We can observe bubbles of hydrogen gas being formed around zinc granules. If we touch the conical flask, we can feel a sense of hotness as there is a rise in temperature. So, it’s a exothermic reaction.
Zn + 2HCl → ZnCl2 + H2
As zinc displaces hydrogen from HCl, this a displacement reaction. Hydrogen gas is usually prepared in the laboratory by this reaction.
When zinc granules are added to dilute sulphuric acid, there occurs a change in the state of zinc granules and they are converted to zinc sulphate(ZnSO4) and hydrogen gas is evolved.
Zn + H2SO4 → ZnSO4 + H2
This reaction is exothermic, i.e., it involves release of heat and so the flask becomes hot and temperature of the system increases.