Rate of Reactions
Thermodynamics
Energy transformations
- Conversion of chemical E in nutrients to another form of chemical bond E in ATP
- Conversion of bond E in ATP to cellular work
- Osmotic work (ion pumps)
- Mechanical work (muscle contraction)
- Metabolic work (driving E-requiring biosynthetic reactions)
Chemical Kinetics
The rate of reaction: proportional to the frequency with which the reacting molecules simultaneously collide
The order of reaction: the sum of exponents
- Order = how many molecules have to bump into each other at one time for a reaction to occur
- Zero order: rarely occurs
- 1st order: when on molecule change to another A → B
- 2nd order: when 2 molecules react A + B → P + Q / 2A → P
- 3rd order: rarely occurs A+B+C → P+Q+R
1st Order Rate
→B
V = velocity of the reaction (M/min)
K = rate constant of the reaction
- Mostly, the reactions are reversible and equilibrium does not lie far to one side
- Natural log of the concentration ([A]) id directly proportional to the time
K for 1st order reaction has unit: s-1
Instantaneous rate: the rate of reaction at any specified time point that is the definition
of the derivative
- Half life: time for half of the reactant which is initially present to decompose or change
→ used to determine the amount of material left after a length of time
Radioactive isotope emits an energetic β particle and has a half-life of 14 days
→ half life of 1st order reaction is not dependent on the intial concentration
2nd Order Rate
→P →P+Q
- % change in A versus time
Enzymes Page 1
Thermodynamics
Energy transformations
- Conversion of chemical E in nutrients to another form of chemical bond E in ATP
- Conversion of bond E in ATP to cellular work
- Osmotic work (ion pumps)
- Mechanical work (muscle contraction)
- Metabolic work (driving E-requiring biosynthetic reactions)
Chemical Kinetics
The rate of reaction: proportional to the frequency with which the reacting molecules simultaneously collide
The order of reaction: the sum of exponents
- Order = how many molecules have to bump into each other at one time for a reaction to occur
- Zero order: rarely occurs
- 1st order: when on molecule change to another A → B
- 2nd order: when 2 molecules react A + B → P + Q / 2A → P
- 3rd order: rarely occurs A+B+C → P+Q+R
1st Order Rate
→B
V = velocity of the reaction (M/min)
K = rate constant of the reaction
- Mostly, the reactions are reversible and equilibrium does not lie far to one side
- Natural log of the concentration ([A]) id directly proportional to the time
K for 1st order reaction has unit: s-1
Instantaneous rate: the rate of reaction at any specified time point that is the definition
of the derivative
- Half life: time for half of the reactant which is initially present to decompose or change
→ used to determine the amount of material left after a length of time
Radioactive isotope emits an energetic β particle and has a half-life of 14 days
→ half life of 1st order reaction is not dependent on the intial concentration
2nd Order Rate
→P →P+Q
- % change in A versus time
Enzymes Page 1
