chem targeted areas [WIP]

used to be biochem, but we split off the bio so now it's just chem. wip because last updated probably millenia ago

what flame colour is copper?

green

what flame colour is lithium?

crimson red

what flame colour is potassium?

lilac

what flame colour is sodium?

yellow

what flame colour is calcium?

orange red

what colour precipitate does copper turn in sodium hydroxide?

blue

what colour precipitate does iron ii form in sodium hydroxide?

dirty green

what colour precipitate does iron iii form in sodium hydroxide?

brown

which anions form a white precipitate in sodium hydroxide?

al3+, ca2+, mg2+

which anion turns the sodium hydroxide colourless when it’s added in excess?

al3+

write a balanced symbol equation between the aluminium anion and hydroxide cation?

al3+ + 3OH- —→ al(OH)3

what test is done to test for carbon ions?

add a dilute acid, if fizzing occurs, carbon is present

(remember acid reactions:acid+carbonate—> co2 + h2o +salt

acid+alkali reaction

salt and water

metal+acid reaction

salt and hydrogen

carbonate+acid reaction

CO2, water and salt

acid+ metal oxide reaction

salt and water

what is the test for sulfate ions?

what is the positive result?

add barium chloride solution (ba2+) and hydrochloric acid, white precipitate forms

test for halide ions?

add silver nitrate and dilute nitric acid solutions, precipitate will turn different colours

what is the result for iodides using the halide test?

forms a yellow precipitate

iodide test equation

I- + Ag+ —> AgI

Chloride test result using halide test

white precipitate

chloride test equation

Cl- + Ag+ —> AgCl

Bromine result using halide test

Cream precipitate

bromine test equation

Br- + Ag+ —> AgBr

what are some advantages of using flame emission spectroscopy? (3)

-can see concentrations of the metal ion (lots of information)

-allows for a definite answer (sometimes hard to distinguish between colours using normal flame)

-fast and accurate

what are some disadvantages to normal flame tests? (2)

-inaccurate if samples are contaminated

-uses up sample

alcohol

-OH functional group

used as solvents and fuels

made through fermentation

oxidised to form carboxylic acids

reacts with sodium; one product is hydrogen

neutral pH solution with water

can be made into esters when reacted with carboxylic acids

carboxylic acids

-COOH group

regular acid reactions

can be made into esters when reacted with alcohols

condensation polymers

formed by monomers with two functional groups - either two types of monomer (a diol, HO-[ ]-OH, and a dicarboxylic acid HOOC-[ ]-COOH, or amino acids with amine (NH₂) groups and carboxyl groups (COOH) forming polypeptides)

releases a small molecule, often water, on formation.

natural polymers include proteins, DNA and sugar structures like starch or cellulose

fertilizers and the haber process

potassium is sourced from potassium chloride and sulphate

phosphate rock is mined, reacted with:

• nitric acid to produce phosphoric acid

• sulphuric acid to produce calcium phosphate and calcium sulphate (single superphosphate)

• phosphoric acid to produce calcium phosphate exclusively (triple superphosphate)

freshwater processing

water is filtered (sediment removed) and sterilized (ozone or chlorine added to kill microbes)

test for pure water

test boiling point - should be exactly 100 degrees C

thermosoftening and thermosetting polymers

thermosetting: has crosslinks between chains

thermosoftening: no crosslinks

DNA structure (chem, 3 marks)

double helix, 4 bases, 2 polymer chains

bronze

copper + tin

brass

copper + zinc

early atmosphere

primarily carbon dioxide

trace gases such as ammonia, methane

water vapour + nitrogen released from volcanoes, forming seas + today’s atmosphere. oxygen produced from photosynthesis from marine microorganisms

atmosphere has been stable for ~200mil years

sedimentary rock formation

layers of sediment transported by rivers are compressed over time under their own weight

gases that cause global dimming, acid rain

dimming: carbon particulates/soot

acid rain: nitrogen oxides

wastewater processing

screening: large sediment removed

sedimentation: allows tiny particles to settle, producing sludge and effluent (liquid above sludge).

sludge is anaerobically digested by bacteria, effluent is aerobically treated with bacteria to reduce volume of solid waste