Chemistry paper 2

lithium, sodium, potassium, rubidium, caesium and francium

low melting points, low density, very soft

ionic compounds (lose one outer electron easily)

they become more reactive as you go down the group

they react vigorously and produce hydrogen gas and a hydroxide of the metal

fluorine, chlorine, bromine, iodine and astatine

diatomic molecules and increasing melting and boiling points down the group

Chlorine - green gas

Bromine - red-brown liquid with an orange vapour

Iodine - dark grey crystalline solid with a purple vapour

the elements become less reactive down the group

salts called metal halides

when a more reactive element displaces a less reactive element from a compound

helium, neon, argon, krypton, xenon and radon

colourless gas and monatomic (single atoms)

they have full outer shells and are non-flammable

the boiling, melting and density increase down the group

copper, iron and zinc

they are hard, strong, shiny and conduct heat and electricity with high melting points and densities

iron is used in the haber process for making ammonia

copper has Cu+ and Cu2+

if a metal loses its outer electron to form a positive ion is it more reactive

very reactive metals react vigorously

tested in a fume cupboard

bubbling it through lime water - turning cloudy if co2 is present

makes a squeaky pop with a lightened splint

damp blue litmus paper will be bleached white

dilute nitric acid with a few drops of silver nitrate solution

chloride - white

bromide - cream

iodide - yellow

barium chloride solution produce a white precipitate add hydrochloric acid will fizz

barium chloride solution produce a white precipitate add dilute hydrochloric acid will not dissolve

lithium - red

sodium - yellow

potassium - lilac

calcium - brick red

copper - blue-green

calcium - white

copper - blue

iron(II) - green

iron(III) - brown

zinc - white then colourless

sensitive, fast and accurate

infrared spectroscopy, ultraviolet spectroscopy, gas chromatography and mass spectroscopy

the more solute you dissolve in a given volume the more crowded the molecules are and the more concentrated the solution is

mass of solute / volume of solution

any solution that you know the concentration of

allow you to find out exactly how much acid is needed to neutralise a given quantity of alkali

1 - use a pipette to measure a volume of alkali and add a few drops of indicator

2 - fill a burette with acid and slowly ass it to the alkali

3 - swirl the flask and record the volume of acid used to change the solutions colour

number of moles / volume of solution

the volume occupied by one mole of a gas

gas volume / number of moles

volume = moles x 24

the percentage of product you get from a reaction

actual yield / theoretical yield x 100

the percentage of the mass of the reactants that has been converted into your desired product

total m of desired products / total m of all products x 100

high atom economy use up resources slowly and make less waste meaning sustainable and profitable reactions

how quickly a reaction happens

amount of reactant used or amount of product formed / time

mixing too see-through solutions produces a precipitate which clouds the solution (experiment by using a piece of paper with a mark and observing the time for the mark to become obscured)

use a mass balance to measure the production of gas the quicker the reading on the balance drops - the faster the reaction

use a gas syringe to measure the volume of gas given off, the more gas given off during a time interval - faster the reaction

change in y / change in x

the more successful collisions there are the faster the reaction is (higher rate of reaction)

• increasing temperature

• increasing concentration

• more surface area

a substance that increases the rate of reaction without being chemically changed

measure the reaction rate with x and then without but instead with a known mass if the rate increases and x is unchanged then it is a catalyst

enzymes speed up chemical reactions in living cells eg. respiration

the products can react with each other to produce the original reactants

after while the foward reaction will be going at exactly the same rate as the backward one

the position can be on the right or the left depending on the conditions

temperature, pressure and concentration

states that if there is a change in concentration, pressure or temperature in a reversible reaction the position will move

decrease - move to the exothermic direction

increase - move to the endothermic direction

increase - move towards the side with fewer moles of gas

decrease - move towards the side with more moles of gas

changing conditions

a metal ore is a rock which contains enough metal to make it economically worthwhile

extracted from res chemically by reduction or electrolysis

when an ore is reduced, oxygen is removed from it - the position of the metal in the reactivity series determines whether it can be extracted by reduction

metals that are more reactive than carbon

the copper produced is very pure and is a better conductor

bacteria gets energy from the bonds between atoms in the ore separating out the metal in the process

growing plants in soil containing metal compounds which builds up in the leaves, the plant is then harvested dried and burned to collect the compounds

mixture of two different metals or a metal and a non-metal

iron and carbon - harder, stronger and less likely to rust

copper and zinc - harder and used for musical instruments

copper and tin - resistant to corrosion and used for sculptures

lead and tin - low melting point and is used to connect components

aluminium, copper and magnesium - low density and used for aircraft

redox as iron losses electrons in the presence of oxygen

painting, oiling and coating

the tin acts as a barrier stopping water and oxygen from reaching the surface of metal

the water or oxygen reacts with the more reactive ‘sacrificial’ metal instead of the other metal

a coat of zinc is put onto iron as it is more reactive and will lose electrons in preference to iron

nitrogen obtained from the air and hydrogen obtained from hydrocarbons in a reversible reaction

is a compromise - 200 atm to favour the foward reaction without being too expensive, 450c as the foward reaction is exothermic without temperature being too low that it slows the rate of reaction

makes the reaction go faster without affecting the position of equilibrium

they contain three essential elements (nitrogen, phosphorus and potassium)

ammonia is a base and can be neutralised by acids to make ammonium salts using nitric, sulfuric, phosphoric acid

titration - adding sulfuric acid to ammonia (methyl orange indicator) then without indicator for pure crystals

burning sulfur in air to make sulfur dioxide then oxidising this to make sulfur trioxide, which is used to make sulfuric acid

temperature - 450c exothermic

pressure - increase in pressure to shift the equilibrium to the right

catalyst - vanadium pentoxide

cost of raw materials - refining and extraction costs

availability of raw materials - non-renewable materials will run out

energy costs - reaching and maintaining conditions

rate - optimum conditions

equilibrium position - if position lies to the left then there will be a low yield

materials and manufacturing, transport, product use, disposal

takes large amounts of energy from burning fossil fuels (which are running out)

energy is needed to reprocess materials into new forms however it can be expensive and the product is of a lower quality

the reaction of different monomers - strong, stretchy and easily moulded (water pipes)

baking substances like clay - brittle and stiff

clay is formed from weathered and decomposed rock, it is easily moulded and then fired at a high temperature

heating limestone, sand and sodium carbonate to make soda-lime glass (transparent and strong)

one material embedded in another - fibreglass has a low density but is strong and used for boats