Unit 1: Chemistry for Biology - Energy

Question 1

enthalpy

Answer 1

• potential energy related to the strength of bonds or interactions
• making stronger bonds or interaction decreases enthalpy, releasing energy and increasing system stability

Question 2

change in enthalpy

Answer 2

• change in system energy due to breaking and making bonds or interactions between/within molecules or atoms
• a NEGATIVE change (decrease) in enthalpy increases system stability

Question 3

entropy

Answer 3

• potential energy related to degrees of freedom

- “degrees of freedom” is the motional freedom of molecules or the number of possible arrangements

Question 4

change in entropy

Answer 4

• change in system energy due to increasing or decreasing degrees of freedom of molecules
• a POSITIVE change in entropy increases system stability

Question 5

free energy

Answer 5

• total system potential energy

Question 6

change in free energy

Answer 6

• change in system energy when you combine the change in enthalpy and entropy
• free energy = (change in enthalpy) - (temperature x change in entropy)
• if free energy change for a system is NEGATIVE, the system has lost energy and become more stable
• processes that have NEGATIVE free energy are said to be SPONTANEOUS (favourable)

Question 7

spontaneous process

Answer 7

• energy has been released and reactions moves from less stable to more stable (favoured)
• if energy input is required to drive something forward, the process is non-spontaneous (less favourable as reactions moves from more stable to less stable)