Chapter U5, Problem 2STP

Interpretation Introduction

Interpretation:

For the reaction between NaHCO₃ and HCl carried out in a beaker, the evidence indicating energy transferred from the surroundings to the beaker needs to be identified from the given options.

Concept introduction:

Chemical reactions in general involve an exchange of heat between the system (reactants and products) and the surroundings.

An endothermic process involves absorption of heat by the system from the surroundings, whereas an exothermic process involves liberation of heat by the system to the surroundings.

Answer to Problem 2STP

(D) The beaker would feel hot to the touch

Explanation of Solution

The given reaction is:

${\text{NaHCO}}_{\text{3 }}\text{+ HCl}\to {\text{NaCl + H}}_{\text{2}}{\text{CO}}_{\text{3}}$

Here, the system is the beaker containing the above reactants and products. If energy were transferred from the surroundings into the system, then the temperature inside the beaker would increase and it would feel hot to the touch.

Conclusion

Therefore, the evidence that would indicate that energy is transferred from the surroundings to the system is that the beaker would feel hot to the touch