VCE Chemistry

prop

3

but

4

Non renewable examples;

coal, coal seam gas and crude oil

Non-renewable impacts;

negative = explosive, deforestation, greenhouse gases
positive = higher energy content, cheaper

Renewable examples;

bio gas, bio diesel and bioethanol

Renewable impacts;

positive = local, less greenhouse gases, bio degradable
negative = lower energy content, high water usage, expensive

exo - the enthaply of....

the products is less than the enthaply of the reactants

endo - the enthaply of...

products is higher than the enthaply of the reactants

complete combustion

O2 is excess and clean blue flame

incomplete combustion

O2 is limiting and yellow flame

electrolyte

solution with ions that conducts electricity

salt bridge

connect the half cells internally and maintains electrical neutrality

primary cells...

cannot be recharged as the electrodes are consumed

secondary cells...

can be recharged by connecting them to an external source

fuel cells...

convert the chemical energy of a fuel into electricity through a reaction with oxygen

cell being recharged means...

you swap the products and reactants around

density formula

D=m/v

galvanic cells are....

a spontaneous reaction where chemical energy goes to electrical energy

electron flow...

negative to positive

inert elements

carbon, platinum, gold and mercury

Fuel cells advantages =

efficient as they convert chemical energy to electricity, hydrogen fuel cells only produce water and heat as by products with no greenhouse gases, can be used in variety of fuels

fuel cells disadvantages =

require constant fuel supply, expensive, storage and safety of hydrogen fuel

∆H =

Hproducts - Hreactants = kJmol -1

what is pressure?

force exerted on an area

OIL RIG

Oxidation is loss of e-
Reduction is gain of e-

In a galvanic cell the anode is _____ and the cathode is _____

negative, positive (ANOX and REDCAT)

How to increase the rate of an reaction?

increase temp, surface area, concentration and pressure

when a catalyst is added...

it decreases the activation energy by creating an alternative reactive pathway and thus the proportion of successful collisions increases.

Reversible reactions occur...

in closed systems and cannot achieve 100% yield

What is the equil constant only affected by?

temp

K>10^4

equil contains more products

K < 10^-4

the equil contains more reactants

Q>K

reverse reaction

Q<K

forward reaction

As pressure increases...

volume decreases

If pressure is increased, and mole ratio is 1:2

forwards reaction is favored

If pressure is increased, and mole ratio is 2:1

reverse reaction is favored

When concentration of reactants increase

forward reaction

When concentration of reactants decrease

reverse reaction

When con of products increase

reverse reaction

When con of products decrease

forward reaction

when coeffs are halved...

Kc = square root

when reaction is reversed...

Kc = 1/number

when coeffs are doubled...

Kc^2

when coeff reversed and halved...

1/square root

Electrolytic reactions are...

- non-spontaneous
- energy is required
- anode is positive
- cathode is negative

what happens in discharge?

galvanic cells producing electrical energy

what happens in recharge?

electrolytic cells producing chemical energy

Q =

charge (C)

I =

current (A)

T =

time (s)

F =

96500 C

n(e-) = Q / F

Q = n(e-) x F

adding more reactant shifts the reaction..

to the RHS thus a forward reaction

adding more products shifts the reaction...

to the LHS thus a reverse reaction

by increasing the volume (decreasing pressure) it shifts...

where the most particles are

when volumes is decreased and pressure is increased..

shifts the side with less particles

adding a catalyst and inert gas...

has no effect on the equil

when temp increases, for exo...

LHS

when temp increases for endo...

shifts the RHS

adding H2O (dilution)

direction with most particles

removing a product...

shifts to RHS thus forward reaction