topic 4 - inorganis

What is produced when group 2 reacts with water

Metal hydroxide - base

What is the trend in reactivity down the group 2

Increases as the ion gets larger, more shielding so loses the electrons more easily

How does mg react with cold water compared to with stream

Very slowly with cold water but vigorously with steam and so produces MgO instead of hydroxide

What is made when group 2 reacts with oxygen

Base is formed- metal oxide

What is made when group 2 reacts with chlorides

Metal chloride

What is made when metal oxides react with water

Form bases which can be used to neutralise acids

How does MgO react with water

Reacts very slowly

How does beryllium oxide react with water

It doesn’t react with water and the hydroxide is insoluble

What is the trend down group 2 hydroxides in terms of how alkaline they become

Becomes more strongly alkaline as hydroxides become more soluble so OH- ions lost easier

What is the trend of solubility of group 2 sulfates

Becomes less soluble down the group

Why do the solubility of group 2 sulfates decrease

Ion gets larger so hydration enthalpy gets less negative as lower charge density so attracts the h20 molecules less strongly so less energy is released when hydrated = dissolving becomes less energetically favourable

What is the solubility of group 2 hydroxides down the group

More soluble down the group

Why do group 2 hydroxides become more soluble down the group

Ion gets larger so lattice enthalpy gets less negative as the large metal ion attracts the OH- ions less strongly so easier to seperate - less energy needed to seperate so dissolution becomes energetically favourable

What do carbonates thermally decompose into

CO2 and oxides

What do group 2 nitrates thermal decompression into

Metal oxides, oxygen and nitrogen dioxide

What is the trend of thermal stability of group 2 nitrates and carbonates down group

They become more thermally stable

Explain why group 2 nitrates become more thermally stable down the group

As the cations get larger they have a less polarising effect and distorts the nitrate ion less, the N-O bond is weakened less so it is less easily broken down making it more thermally stable

What is the thermal stability of group 1 carbonates

Group 1 carbonates dont decompose except from lithium

Why does lithium and not the whole group, decompose

As they only have a 1+ charge so doesn’t have a big enough charge to polarise the carbonate ion however lithium ion is very small and has a polarising effect

What do group 1 nitrates break down in to

Nitriles and oxygen except for lithium nitrate which produces Li2O + NO2+ O2

Why is group1 more thermally stable than group 2

Group 2 have a greater charge than group 1 so group 1 causes less distortion

How do u test for the thermal stability of NO3

• measure how long it takes a specific amount for o2 to be produced using gas syringe or amount needed to relight a growling splint

• Amount of time it takes until a specific amount of NO2 is produced it is a brown gas so easily observed but is toxic so do in a fume cupboard

How to test for the thermal stability of CO3

Time it takes until a specific amount of co2 is produced, co2 turns limewater cloudy so quicker it turns cloudy the more co2 present

Explain for the different colours in flame test

The heat causes the electrons in shells to move to a higher energy level, the electron is unstable so drops back down, as it drops back down to lower energy level, energy is emitted in the form of light, the difference in energy levels determines the wavelength of light emitted

What colour flame is Rb

Red

What colour flame is calcium

Dark red

What colour is lithium and Strontium

Crimson

What flame colour is sodium

Yellow/ orange

Why does the state of halogens get more solid down the group

Boiling point increases as London force increases due to increasing size and the relative mass of atoms so more energy is needed to overcome

Trend of electronegativity down group 7

Decreases down the group, the atoms get larger so distance increases from the nucleus, more shielding so its harder for the atom to attract electrons in a covalent bond

Why are halides reducing agents

As they lose electrons

How do u carry out the test of halide ions with silver nitrate

Add dilute nitric acid and then silver nitrate to the halide

What is the purpose of the dilute nitric acid when testing halide ions using silver nitrate

It reacts with and gets rid of any carbonates present to avoid getting a false test

What is precipitate colour formed when chlorine reacts with silver nitrate

White

What is produced when bromine reacts with silver nitrate

A cream precipitate

What happens when u add dilute ammonia to the silver halide predicates

• chlorine dissolves

• No affect on others

What happens when you add conc ammonia to silver halides

• bromine precipitate dissolves but no affect on others

What happens to silver iodide when conc ammonia is added

No affect as it is insoluble in it

What is ion test for sulfates

Add HCl to remove any carbonates and add barium chloride, if present a white precipitate forms

What is test for ammonium compounds

• add NaOH and gently heat if present then ammonia gas is produced

• Use damp red litmus, ammonia will dissolve in water and turn litmus blue

How to do hydroxide ion test

It will turn red litmus blue but must do further tests

What is ionic equation for ammonium compound test

NH4 + OH- = NH3 + H2O