Question

In the lab, an aqueous solution of HCl reacts with a powdered solid in a coffee-cup calorimeter. The temperature of the solution increases from 19.5°C to 23.2°C. What conclusion can you draw about the change in enthalpy of reaction? Be sure to clearly define the system and surroundings.

Answer 1

Answer:

Molecules of substance(s) that are reacting are termed as a system and the rest environing the system are termed as the surroundings.

In lab, when HCl solution was added with powdered solid in cofee cup calorimeter it resulted in change in temperature of the solution from 19.5 degree Celsis to 23.2 degree Celsius. This rise in temperature od solution (system) indicates that heat would have been evolved during the chemical reaction between HCl and powdered solid.

This rise in temperature would have also raised the tempreature of coffee-cup calorimeter(surrounding).

And as we know that in a chemical reaction when heat is released into its surruondings it is termed as an Exothermic reaction.

So, the enthalpy change between the reaction of HCl and powdered soild is negative ( heat is released).