Thermochemistry

Question 1

What is enthalpy? 

Answer 1

Enthalpy is the heat energy content of a chemical substance or chemical system

Question 2

What is enthalpy change?

Answer 2

This refers to the heat change that occurs at constant pressure and specific temperature when specific quantities of reactants are completely changed to Products.

Question 3

What is an exothermic reaction?

Answer 3

This is a reaction that proceeds by releasing heat energy to the surrounding

Question 4

What is the formula for enthalpy change?

Answer 4

Enthalpy change is equal to enthalpy of products minus enthalpy of reactants

Question 5

Is the enthalpy change for exothermic reactions positive or negative? Give a reason for your answer.

Answer 5

Then negative because the energy content of product is lower than that of reactants

Question 6

What is an endothermic reaction?

Answer 6

This is a reaction that proceeds by absorbing heat from the surroundings

Question 7

Is the enthalpy change for endothermic reactions positive or negative? Give a reason for your answer.

Answer 7

It is positive because the heat energy content of Products is higher than that’s a reactant

Question 8

Are the values in enthalpy of combustion positive or negative?

Answer 8

Negative