Cram Flashcards
Flame test colours (6)
Li+ crimson
Na+ yellow
K+ lilac
Ca2+ brick red
Ba2+ apple green
Cu2+ green/ blue
What reacts with metal ions to form coloured precipitates
Colours pls (6)
NaOH
Ca2+ white insoluble in excess NaOH
Mg2+ white insoluble in excess NaOH
Al3+ white soluble
Cu2+ blue
Fe2+ (dirty) green
Fe3+ brown
Test for carbonate
Result
Add an acid
Produces CO2, cloudy limewater
Test for sulphate
Result
Dilute HCL and BaCl2
White insoluble precipitate (BaSO4)
Test for halide ions
Result
Dilute HNO3 and AgNO3
Produces different colour precipitates
Cl- white
Br- cream
I- yellow
3 advantages and 2 disadvantages of instrumental methods of analysis
More accurate and sensitive
Faster
Enables small samples to be analysed
Need to have a skilled/ trained specialist to use it
Very expensive
What does mass spectroscopy show (2)
The relative molecular mass of a compound
Shows the structure by how the sample breaks up as it passes though, the fragmentation pattern can be matched to known compounds
Colours of phenolphthalein indicator
Alkali pink
Acid colourless
How to get mol/dm3 to g/dm3
x Mr
Alcohol to carboxylic acid?
And the other product?
Add an oxidising agent [such as potassium dichromate (VI) solution], H2SO4 catalyst and water bath to alcohol
Water
Sodium + ethanol ->
Sodium ethoxide + hydrogen
Test for carboxylic acid
What does it produce
Add a carbonate (e.g. sodium carbonate)
Carbon dioxide and water
Volatile meaning
Evaporates easily
Making an ester
+ 3 conditions
Alcohol + carboxylic acid
Add CONCENTRATED H2SO4 catalyst
Got water bath
Add NaHCO3 to neutralise acid catalyst
The Haber process
H2 is from methane at high temperatures
N2 is from the air by fractional distillation
Gas stream contains purified H2 and N2
Converter heats the mixture to 450°C and compresses to a pressure of 200atm
Reaction vessel has the gases over an iron catalyst
Separator cools gases
Only ammonia condenses and is removed as a liquid
Unreacted H2 and N2 are recycled back to the reaction vessel
Activation energy definition
Energy required to break the bonds between the atoms of the reactants
Minimum amount of energy that particles need for a reaction to start
Why does the reaction become more exothermic as the alcohol increases in size
Extra energy released forming bonds in the products is even greater as more CO2 and H2O molecules are produced.
This is greater than the energy required to break the extra bonds of the reactants as there are more bonds to break due to the increase in size
Where does electrolysis of water take place
Hoffman Voltameter
How is air separated by fractional distillation
Air is filtered to remove any solid particles
Air is compressed
Pipes containing cold water cools air and solid CO2 and H2O are removed
Pressure is released so cools to 200°C so turns into liquid air
Fractional distillation separates gases at different boiling points
N2 boils, O2 does not, Ar collected between
What is amphoteric
Behave like both acids and bases as they can react and dissolve in both
They do not dissolve in water
Bioleaching
Bacteria feeds on ore
Chemical reaction produces a solution of Cu2+ ions
Add H2SO4 to make CuSO4
Electrolysis or displacement with an iron nail first
Phytomining
Grow plants on wasteland with low grade copper ore
Plants absorb Cu2+ ions from soil through roots
Burn plants, ash contains CuO
Add H2SO4 to make CuSO4
Electrolysis or displacement with an iron nail first
Conditions for low density polyethene
High pressure and O2
Conditions for high density polyethene
Catalyst at 50°C with slightly raised pressure
Reactivity series
Group 1 (potassium, sodium) Group 2 (calcium, magnesium) Aluminium CARBON transition metals (zinc, iron, tin, lead) HYDROGEN Copper Silver Gold Platinum
Which electrode do the plating material and object need to be
Anode is the playing material
Cathode is the object that will be played
How do the beads help fractional distillation
Increases surface area
Beads condense substances with higher boiling points more readily so drop back down
Gas chromatography steps
Sample mixture is vaporised and injected at top of column
A ‘carrier’ gas moves sample vapour through column
Different substances in the sample have different attractions to the column (this is the basis of their separation)
-substances with strong attractions take a longer time to travel through so have a long retention time
How can one get a louder squeaky pop test
Allow the hydrogen to mix with some oxygen
