Chm101

Question 1

What’s thermochemistry

Answer 1

This is the study of heat changes that accompany chemical reactions and physical changes

Question 2

What is a great extent based on the law of conservation of energy

Answer 2

Thermochemistry

Question 3

What is physical changes

Answer 3

Is a change in state that does not involve a change in composition e.g crystallization and evaporation

Question 4

What is Chemical reaction/ change

Answer 4

This is a process that involves the change of chemical composition e.g neutralization of an acid by base , oxidation

Question 5

What physiochemical changes classified as ?

Answer 5

They are classified as endothermic, accompanied by the absorption of heat
Or
Exothermic accompanied with the evolution of heat

Question 6

What is the sign when heat is released

Answer 6

Negative

Question 7

What is the sign when heat is absorbed

Answer 7

Positive

Question 8

What is used to denote heat change

Answer 8

DH or DE

E.g C+O2 - CO2 DH= -393.513kj

Question 9

What is the representation of an enthalpy change

Answer 9

DH= H prod -H react

For endothermic reaction H prod>H react

For exothermic reaction H prod < H react

Question 10

What is thermochemical equation

Answer 10

These an equation in with values of heat changes are given

Question 11

What happens when the direction of chemical reaction are reversed

Answer 11

The sign of DH must be changed
E.g CO2 -C + O2 DH=393.513kj