c4 - predicting reactions + identifying products

3 advantages of instrumental techniques

speedy accurate sensitive

how do you read a mass spectrum

reading the height of the peak most to the right (molecular peak) to find the rfm of the substance

how do you identify metal cations

add sodium hydroxide to the solution, if a hydroxide precipitate forms, it is a metal cation

metal hydroxide positive results

calcium - white

copper - blue

iron (II) - green

iron (III) - brown

zinc - white (dissolves in excess)

what is the ionic equation for the reaction of calcium with sodium hydroxide

Ca²⁺_(aq) + 2OH^-_(aq)→Ca(OH)_{2 (s)}

how do you test for sulfate ions

add barium chloride and then hydrochloric acid

barium sulfate doesn’t react with hydrochloric acid so if a white precipitate form and it doesn’t redissolve, the solution contains sulfate ions

how do you test for carbonate ions - 4 steps

add barium chloride to produce a white precipitate of barium carbonate

add hydrochloric acid, if carbonate ions are present it will fizz as a gas is made

you collect the gas using a gas syringe and bubble it through limewater

if it turns cloudy, it is carbon dioxide meaning carbonate ions were present

what are the ionic equations for the carbonate test

Ba²⁺ _(aq) + CO₃^2- _(aq) → BaCO_{3 (s)}
BaCO_{3 (s)} + 2H⁺_(aq) → Ba²⁺_(aq) + CO_{2 (g)} + H₂O _(l)

how do you test for halide ions

add dilute nitric acid and a few drops of silver nitrate solution

halide test results

white - chloride

cream - bromide

yellow - iodide

how do you test for oxygen

glowing splint

positive result: relights

how do you test for hydrogen

lit splint

positive result: squeaky pop

how do you test for chlorine

damp blue litmus paper

positive result: turns red then bleaches white

how do you test for carbon dioxide

bubble it through limewater

positive result: turns cloudy

5 properties of transition metals

metals, good conductors, high melting and boiling points (except mercury thats a liquid), high density, unreactive

what is iron a catalyst for

the haber process to make ammonia

what is vanadium pentoxide a catalyst for

the contact process to make sulfuric acid

what happens as you go down the group of noble gases

boiling point, melting point and density increase

what are group 0 elements

monotomic, inert, colourless gases

what is the formula of a halogen displacement reaction between chlorine and potassium bromide

Cl₂ + 2KBr → Br₂ + 2KCl

what halides displace

chlorine displaces bromide and iodide

bromine displaces iodide

iodine doesn’t displace anything

what happens when you go down the group of halogens

melting points and boiling points increase and reactivity decreases

what are group 7 elements

diatomic halogens

what are the halogens like at room temperature

chlorine - green gas

bromine - red-brown liquid giving off an orange vapour

iodine - dark grey crystalline solid giving off a purple vapour

what are 3 properties of alkali metals

low melting and boiling points

low density

soft and shiny when cut

what happens as you go down group 1

melting and boiling points decrease and reactivity increases

why does reactivity increase as you go down group 1

the distance from the nucleus increases

shielding increases

the force of attraction between the nucleus and the electron decreases

its easier to lose electron

what happens when alkali metals are put into water

they react vigorously and produce hydrogen gas and a metal hydroxide

lithium moves and fizzes

sodium also melts

potassium also ignites

rubidium and caesium can explode

metal + acid →

salt + hydrogen

what are instrumental methods

using machines to carry out an analysis of a substance