chemistry bits

universal indicator alkali

blue/purple

universal indicator acid

red

element which forms a basic oxide

copper

bromine at room temp

red-brown liquid

chlorine at room temp

yellow-green gas

iodine at room temp

grey solid

rf equation

distance moved by substance/distance moved by solvent

obtain pure dry crystals from salt solution

heat to evaporate water,

leave to cool,

filter to obtain crystals,

leave to dry (oven)

diamond electricity

does not conduct electricity as no free electrons

diamond melting point

very high as strong covalent bonds in rigid structure

diamond uses

cutting tools as very hard

graphite electricity

conducts electricity as contains delocalised electrons free to move

graphite melting point

high as contains lots of strong covalent bonds

graphite uses

lubricant as layers can slide over each other

diamond and graphite structure

giant covalent structures

diamond structure

tetrahedral

graphite structure

hexagonal

why ionic compound has high melting point

giant structure, strong electrostatic attraction between oppositely charged ions so large amount of energy needed to break bonds

forces of attraction in covalent bond

sharing of electrons between two attracted nuclei

half equation for formation of oxygen during electrolysis

4OH- = O2 + 2H2O + 4e

why do ionic compounds need to be molten to conduct electrolysis

when solid, ions arent free to flow and conduct charge but when molten are mobile

why metals are malleable

layers of atoms which can slider over eachother

what happens at anode

oxidation, loss of electrons

what happens at cathode

reduction, gain of electrons

percantage change

change/original x 100

why use powder

larger surface area so reacts quicker

why is argon unreactive

full outer shell so doesnt lose or gain electrons

percentage of oxygen in air

21%

what forms acid rain

nitrogen dixoide and water (nitric acid), or sulfur dioxide and water (sulfuric acid)

magnesium and oxygen observation

bright white flame, formation of white powder

test for carbon dioxide

bubble through limewater and turns cloudy

variables to be controlled

concentration of acid, surface area of metal, temperature, volume of acid,

percentage of nitrogen in air

78%

percentage of argon in air

1%

percentage of carbon dioxide in air

0\.04%

colour of methyl orange

yellow in alkali, red in acid

method to produce dry crystals of hydrated

add powder to acid until powder is in excess,

filter off excess,

heat to evaporate water,

cool,

filter crystals,

leave in warm place to dry

phenolphthalein colours

colourless in acid, pink in alkali

titration method

use pipette to add 25cm3 of acid to conical flask,

add a few drops of indicator,

add acid to burette and record initial reading,

drop acid into flask and swirl continuously until it changes colour,

take final burette reading and find volume of acid needed by working out the difference,

repeat to get concordant results

why is the reaction exothermic in terms of bonds

more energy is given out when bonds are made than is when taken in when bonds are broken

why is soot formed

incomplete combustion due to limited oxygen supply

soot name

carbon

heat energy equation

q x c x temp change

why is volume collected less than expected

gas escaped before bung is placed on flask

why is measuring cylinder not necessary

acid is in excess so an accurate measurement isnt needed

dynamic equilibrium

position in a reversible reaction where the concentration of reactants and products remain constant and the forward and backward reactions continue to occur

pressure increase effect on equilibrium

moves to direction of fewer molecules of gas

concentration increase effect on equilibrium

moves away from what gained more conc

temperature increase effect on equilibrium

moves in endothermic direction

catalyst effect on yield

none as increases rate of both backwards and forwads reaction

catalyst effect on rate of reaction

provides alternate pathway so lower activation energy needed for reaction to begin, meaning more collisions so speeds up rate of reaction

yield change depending on equilibrium

if equilibrium shifts to the right the yield of products will increase

test for chlorine

damp litmus paper goes from red to white

test for ammonia

turns red litmus paper blue

lithium flame test

crimson

potassium flame test

lilac

calcium flame test

orange-red

sodium flame test

yellow

copper flame test

blue-green

iron 3 hydroxide colour

brown

iron 2 hydroxide colour

green

copper hydroxide colour

green

test for halides

silver nitrate + nitric acid

test for sulfates

barium chloride + hydrochloric acid

positive result for sulfate

white precipitate

test for water

white copper 2 sulfate turns blue, cobakt 2 chloride strips turn pink

test for pure water

boils at 100\*C or melts at 0

products of incomplete combustion of an alkane

carbon monoxide, water

general formula for alkene

CnH2n

unsaturated meaning

contains a double bond

test that a hydrocarbon is unsaturated

add bromine solution and it will turn from orange to colourless

enthalpy change equation

heat energy/moles

why crack long chains into short ones

short chains are more useful and have a higher demand

solid to gas change

sublimation

test for copper and iron 2

add sodium hydroxide solution, if blue precipitate forms copper is present, if green precipitate forms iron is present

test for chloride and bromide

add silver nitrate, if white precipitate forms chloride is present, if cream precipitate forms bromide is present

test to distinguish between alkane and alkene

bromide solution stays orange for alkane, and becomes colourless for alkene

ionic bond

electrostatic attraction between oppositely charged atoms

why is it not safe to heat alcohol in an evaporating basin with a bunsen burner

they are flammable

properties of aluminium

high mp, resistant to corrosion, good conductor of thermal energy

why is fermentation of ethanol anaerobic

ethanol would react with oxygen to make ethanoic acid

equation for complete combustion of ethanol in air

C2H5OH + 3O2 = 2CO2 + 3H2O

conditions for making ethanol with steam

300\*C, 60-70 atm

dynamic equilibrium

state where a reaction is taking place in both reactions at the same rate at the same time

mol equation for mol/vol topic

vol/24000cm3

why is pencil line below water line

so inks dont mix with water

hydrogen qualities

flammable, low density

isomer

compound with the same molecular formula but different structural formula

exothermic energy profile

products below reactants

bond breaking

endothermic, needs heat energy

bond making

exothermic, releases heat energy

problem with disposal of addition polymers

landfill sites getting full, greenhouse gases produced when burned

lower hydrocarbon qualities in crude oil

darker colour, higher boiling point, high viscosity

why is carbon monoxide poisonous

reduces capacity of blood to transport oxygen

complete combustion of hydrocarbon products

carbon dioxide + water

crude oil fractions top to bottom

gases, petrol, kerosene, diesel oil, fuel oil, bitumen

crude oil rhyme

good penguins keep diving for bass

chemical test for water

anhydrous copper sulfate turns from white to blue

reactivity trend down group 7

gets less reactive as you go down

combustion of hydrogen in air

2H2 + O2 = 2H2O