topic 2 - thermodynamics

Question 1

system vs surroundings

Answer 1

system = what we are interested in
surroundings = everything outside the system

Question 2

what is the difference between an isolated, closed, and open system

Answer 2

isolated = doesn’t exchange matter or energy
closed = exchanges energy only
open = exchanges energy and matter

Question 3

what type of system is a bio system

Answer 3

open system
- must acquire energy and matter from their surroundings

Question 4

what types of work are done inside the cell

Answer 4

synthesis of bio molecules
transport of molecules
cell division
motility

Question 5

what is the 1st law of thermodynamics

Answer 5

energy is neither created nor destroyed
energy can change locations, and into different forms

Question 6

how does potential energy change inside an atom

Answer 6

as an electron moves closer to the atomic nucleus, PE is converted to toehr types of energy
farther away the e- is from the nucleus = more PE

Question 7

what type of bonds give molecules the most PE

Answer 7

more covalent bonds = more PE

Question 8

what happens to PE and KE during mvmt along an electrochemical gradient

Answer 8

relative concen of molecules on each side of the membrane becomes a source of PE (high concen = high PE)
free mvmt across membrane along concen gradient means PE is converted to KE

Question 9

what is enthalpy

Answer 9

sum of PE and KE in the system
measured as the amount of heat that is released to/absorbed from the surroundings
delta H kJ/mol

Question 10

what is an exothermic reaction in terms of enthalpy

Answer 10

products have less enthalpy than the reactants
energy released as heat

Question 11

what is an exothermic reaction in terms of enthalpy

Answer 11

products have more enthalpy than the reactants
energy absorbed

Question 12

what does it mean if a reaction is spontaneous

Answer 12

reaction can happen under the current set of conditions
energetically favourable
NOT instantaneous (can happen over variety of time frames)

is a reaction is spontaneous then (under the same conditions) it is non spontaneous in the opposite direction

Question 13

what does it mean if a reaction is non spontaneous

Answer 13

reaction can not occur under the current set of conditions

Question 14

what are important current conditions for reactions

Answer 14

pH
temp
concentration of reactants and products
pressure
salinity

changes in condition can potentially make the reaction spontaneous in the reverse direction

Question 15

does enthalpy determine if a reaction is spontaneous

Answer 15

no
exo and endothermic can both be spontaneous

Question 16

what is entropy

Answer 16

S - measured in J/molK
- how dispersed/spread out the energy of the system and its surroundings is
- everything has entropy

Question 17

what is the difference in delta H (enthalpy) when heat is released and absorbed

Answer 17

heat released = - delta H
heat absorbed = + delta H

Question 18

what is the difference in delta S when energy is more and less dispersed

Answer 18

more dispersed = + delta S (spontaneous)
less dispersed = - delta S (non spontaneous - violates 2nd law of thermodynamics)

Question 19

what is the second law of thermodynamics

Answer 19

total entropy of the unvierse is always increasing
- every transformation must increase the total entropy of the universe
entropy determines spontaneity

Question 20

can the entropy of the system decrease

Answer 20

yes - as long as the entropy of the surroundings increases to a greater degree (positive change overall)

Question 21

what does it mean if a reaction is exergonic

Answer 21

• free energy is released
• • delta G
• spontaneous
• products have less free energy than reactants

Question 22

what does if mean if a reaction is endergonic

Answer 22

• free energy is gained
• • delta G
• non spontaneous
• products have more free energy than reactants

Question 23

what is free energy

Answer 23

G - measured in kJ/mol
energy of the system that is available to do work
- for work to occur, the energy must be available to carry out the change (reactants have more energy than the products)

Question 24

what is the difference in delta G when energy is/isn’t available

Answer 24

energy available = - delta G
energy not available = + delta G

Question 25

how to calculate delta G (free energy change)

Answer 25

delta G = -T(delta S total)

delta G = delta H - T(delta S system)

Question 26

when does chemical equilibrium occur

Answer 26

when the rates of the forwards and reverse reactions are equal
- reactions never go to completion
- proportion of reactants and products are constant

Question 27

what is metabolism

Answer 27

sum of all reactions in a cell

Question 28

what is catabolism

Answer 28

breaking down of complex molecules
- proteins broken into amino acids
- break down fats/carbs
exergonic (releases chem energy)

Question 29

what is anabolism

Answer 29

building up of complex molecules
- building muscle, DNA, proteins

overall process = endergonic
indiviudal reactions = exergonic

Question 30

what is a connected reaction

Answer 30

product of the first reaction is the substrate (reactant) for the second reaction

(first reaction of glycolysis produces G6P and the second reaction uses it)

Question 31

what are the components of ATP

Answer 31

nitrogenous base - adenine
sugar - ribose
3 phosphates

Question 32

why does ATP have PE

Answer 32

compressed negative charges in the phosphate groups

Question 33

what occurs with the breakdown of ATP

Answer 33

breaking ATP bonds with water = hydrolysis
products = Pi, ADP
negative change in delta G (free energy) - spontaneous

Question 34

what is a coupled reaction

Answer 34

2 reactions that happen at the same time and in the same place
- used to carry out reactions that otherwise would be endergonic (use released free energy from exergonic to drive endergonic)