1026: Chemistry of life.

Question 1

Define total internal energy of a system and give it’s equation.

Answer 1

Internal energy of a system is the sum of work and heat.
U=w+q
U=Internal energy
w=work
q=heat

Question 2

Define an open system.

Answer 2

Both matter and energy can be transferred between the system and the surroundings.

Question 3

Define a closed system.

Answer 3

only energy can be transferred between the system and the surroundings.

Question 4

define an isolated system.

Answer 4

Neither matter nor energy can be transferred between the system and surroundings.

Question 5

Give the first law of thermodynamics: Conservation of energy.

Answer 5

Energy can be transferred between different forms but never created or destroyed.

Question 6

Define work and give it’s formula.

Answer 6

Work is any process that can be used to lift a weight, when work is preformed energy is transferred from the system to it’s surroundings.

Work= force*distance.

Question 7

Give the formula for change in thermal energy.

Answer 7

Q=mcΔt

Question 8

Define enthalpy in a closed system.

Answer 8

H=U+p*V

change in enthalpy is
ΔH=ΔU+Δp*ΔV

Question 9

Describe the movement of energy in a closed system during an endothermic reaction.

Answer 9

Energy taken into the system is more than that is released into the surroundings.

Question 10

Describe the movement of energy in a closed system during an exothermic reaction.

Answer 10

Energy released from the system to surroundings is more than taken into the system.

Question 11

Define the Universal observation.

Answer 11

A hot system in contact with a colder surrounding will spontaneously get colder, at the same time the surroundings will get hotter, the reverse will not happen.

Question 12

Define the second law of thermodynamis.

Answer 12

in an isolated system entropy can only ever increase.

Question 13

Define the Change of entropy and give it’s formula.

Answer 13

Change of entropy is proportional to the heat transferred from the system to the surroundings.

△S⪰△q/T

q= joules (J)
T= Temp (K)
So if heat is transferred to a system entropy will increase.

Question 14

Describe entropy changes during endothermic reactions.

Answer 14

Entropy of the system increases but entropy of surroundings decreases.

Question 15

Describe entropy changes during an exothermic reaction.

Answer 15

Entropy of the system decreases but entropy of the surroundings increases.

Question 16

What is required for a reaction to occur spontaneously.

Answer 16

total entropy of the system and the surroundings needs to increase.

△S total=△S sys+△S sur>0

Question 17

Name the two quantities describing a system.

Answer 17

Macrostates
Microstates

Question 18

Give three examples of macroststes and microststes.

Answer 18

Macrostates:
Temperature
Pressure
Volume

Microstates:
Kinetic energy
Force
Velocity

Question 19

Define entropy and give It’s formula.

Answer 19

The number of microstates of a system.

S=KB*in(Ω)
Ω=number of microstates.
kB= Boltzmann constant

Question 20

Defien Gibbs free energy and give it’s formula

Answer 20

△G is the energy from a reaction that is available to generate work.

△G=△H-T△S

Question 21

Define the hydrophobic effect.

Answer 21

The observed tendency of nonpolar substances to aggregate in aqueous solution and exclude water molecules.

Question 22

show general formula for Protein ligand bonding and give two characteristic effecting it.

Answer 22

P+l ⇄ PL

1. Kinetics- the rate at which something appears or disappears.
2. their affinities- the strength of interaction between protein and ligand.

Question 23

Give general association Constant formula for a protein and ligand.

Answer 23

,,,,,,,,,[PL]
KA= ———
[P]*[L]

Question 24

give genal Dissociation constant formula for protein and ligand.

Answer 24

,,,,,,,[P]*[L] 1
KD=———- = —
[PL] KA