life 102

energy- the ability to do work

Thermodynamics- study the effects of work, heat and energy on a system

kinetic energy- energy in movement

potential energy- energy that exists because of the relative position of stuff in place

1st law of thermodynamics- energy in the universe cannot be created nor destroyed, only transferred in form (energy is conserved)

2nd law of thermodynamics_ entropy (disorder) increases- energy always flows from an ordered state to a disordered state

Transformations increase disorder - entropy

Energy conversion + entropy - at every step of energy transformation, heat energy is always lost

3rd Law – at absolute zero, all movement stops

• As temp -> 0, entropy falls towards a universal constant

Energy & Reactions

Molecules in biology- are in motion and therefore have a certain amount of kinetic energy.

Different types of bonds- may be associated with storing different amounts of energy. This = different potential energy.

When reactions transfer heat to the environment - exothermic.

When reactions transfer heat from the environment - endothermic.

Chemical reaction- involves breaking bonds and making bonds

starting materials- reactants

final materials- products

chemical reactions may- absorb energy overall or release energy overall

endothermic reaction- a chemical or physical process that absorbs heat from its surroundings, resulting in a positive enthalpy change (ΔH > 0) and a cooling effect on the environment.

endothermic reactions happen when the products are- Energy level of products is higher than energy level of reactants

Exothermic- Heat energy is released to the surroundings

Exothermic happens when the products of energy levels are- Energy level of products is lower than energy level of reactants

Rusting is a- spontaneous reaction

Ice melting is a- spontaneous reaction

enthalpy- the amount of heat absorbed or released during a reaction

Change in heat represented by ΔH

• Exothermic reactions have a negative

ΔH; they release heat

• Endothermic reactions have a positive

ΔH; they absorb heat

entropy- the amount of disorder in the system

reactions tend toward- increasing entropy (increasing disorder)

change in entropy represented by ΔS

Enthalpy - amount of heat transferred in a reaction

Entropy - amount of disorder resulting from a reaction

Gibbs free energy- measure of whether a reaction will occur spontaneously

When you have less free energy after the reaction- it is spontaneous

Endergonic reactions – requires energy into system

Endergonic reactions make what- build up, make bonds

Exergonic– Releases energy out of the system

exergonic reactions break what- breaks bonds

Exergonic - Releases Energy

Endergonic - Consumes Energy

Non-Spontaneous

A non-spontaneous reaction will have a- positive G.△

If the reaction is endothermic, △H will be- △ positive (absorbs heat)

If the reaction become less disordered – lower entropy, △S will be△ negative.

So, a positive △H and a negative △S will always make △G positive; the reaction will△ always be non-spontaneous

Spontaneous Reactions

If the reaction is exothermic (-△H) and increases entropy (+△S), it will always be

spontaneous (-△G)

When a reaction increases both entropy (+△S) and enthalpy (+△H; is endothermic), the spontaneity depends on the temperature of the reaction

△G – a form of spontaneity

• Downhill is- spontaneous, the ΔG is negative, it is exergonic, energy is

released (exits) when the reaction occurs.

• Uphill is- non-spontaneous, the ΔG is positive, it is endergonic, energy

is required (enters) for the reaction to occur

Hypotonic: lower solute concentration → water enters cells → swelling.

Hypertonic: higher solute concentration → water leaves cells → shrinking

any reaction that requires an input of energy is a- endergonic reaction