6.3 Calculation of Enthalpy Reaction

Question 1

What are the three different methods to calculate the heat of a reaction/enthalpy?

Answer 1

1. Standard heats of formation
2. Hess’s law of heat summation
3. Summation of average bond enthalpies

Question 2

What are standard conditions?

Answer 2

Conventions that have been developed for which most constants, heats of formation, and enthalpies have been based on

Question 3

What are the standard conditions

Answer 3

Temperature = 298K
Pressure = 1atm
All solid and liquid assumed to be pure
All should are a concentration of 1M

Question 4

What is the standard heat of formation?

Answer 4

Amount of energy required to make one mole of a compound from its constituent elements in their natural or standard state

Question 5

What does it mean when the standard heat of formation is positive?

Answer 5

Input of heat of required to make the compound

Question 6

What does it mean when the standard heat of formation is negative?

Answer 6

Release of heart occurs when a compound is formed

Question 7

What is Hess’s law of summation?

Answer 7

States that if a reaction occurs in several steps then the sum of the energies absorbed or given off in all the steps is equal to the energy for the overall reaction

Question 8

What are the enthalpies of bonds also known as?

Answer 8

Bond dissociation energy