C8 - Chemical Analysis Flashcards
What is the set up for a flame test
Platinum or nichrome wire cleaned with concentrated hydrochloric acid - then wire dipped into a sample of the compound - the placed in blue Bunsen flame
Type of metal for the wire for a flame test
Platinum
What type of flame is wire put into for flame tests
Blue Bunsen flame
What colour does lithium go and why
Lithium crimson - both have an I in them
What colour does sodium go and why
Yellow - soooo yellow
What colour does copper go flame test
Green - as 2 ps in copper and 2 es in green
What colour does potassium go?
Lilac - the fourth letter of both is A
What colour does calcium go in flame test?
orange Red
Calcium = Rad = Red
Give 2 possible issues with the flame test
If wire not clean/mixture of metal ions present
Yellow Bunsen burner flame could mask the colour of the flame produced
What is the result of the sodium hydroxide precipitate test for aluminium, calcium and magnesium (colour)
White
Which compound dissolved as well as turning white in the sodium hydroxide precipitate test?
Aluminium
What colour does copper 2 turn in the sodium hydroxide precipitate test
Blue (as they rhyme)
What colour does iron 2 turn in the sodium hydroxide precipitate test?
Green - as II => ee
What colour does iron 3 turn in sodium hydroxide precipitate test
Brown
Iron has o n and brown has own
What 3 compounds are usually used with the sodium hydroxide test? And why?
Copper, iron II, iron III as it has differentiating colours
How do you test the difference between aluminium, calcium or magnesium
Add excess sodium hydroxide solution
Aluminium precipitate dissolves forming a colourless solution
What is necessary to add for a carbonate test?
Hydrochloric acid
How do you conduct the carbonate test
Collect bubbles with a pipette and bubble this into limewater - check if limewater turns cloudy
What is necessary for the sulfate test to be conducted
Add dilute HCl and Barium chloride solution
What forms if sulfate ions are present?
White precipitate
What is necessary for the halide test?
Nitric acid and silver nitrate solution
Give 3 types of precipitate possible for the halide test
White
Cream
Yellow
What is the positive result for chloride in a halide test
Forms white precipitate - as chloride is clean white
What colour does bromide go in a halide ion test
Cream - as A B C
What is the positive colour for iodide
Yellow - I love Yellow
What is an accurate way to test for ions
Flame emission spectroscopy
Give 4 advantages of flame emission spectroscopy
Can identify ions in a mixture
More sensitive
More accurate
More rapid
How does flame emission spectroscopy work?
Sample is put in flame
Light emitted is passed through a spectroscope and a line spectrum emerges
How are ions identified in flame emission spectroscopy?
A line spectrum unique to each ion type exists
You can compare this to the result you get to identify ion presence
Give 2 ways flame emission spectroscopy can be used
Checks for presence of ions
Measures concentrations of ions in a substance
5what is a formulation
Mixture designed to produce a useful product
How do you find an impure substance
The melting points is lower and the boiling point is higher than the pure substance’s value
What is the gas test for oxygen
Glowing splint into gas - if it relights oxygen is present
What is gas test for hydrogen
Squeaky pop test - burning splint in gas and if it leads to squeaky pop then hydrogen present - as hydrogen burns rapidly
What is the gas test for CO2
Bubble the gas into limewater - and goes from colourless to cloudy if positive
What is the test for chlorine
Damp blue litmus paper placed in the gas - positive is the paper bleaches (blue->red->white)
what is a pure substance
a single element or compound - not mixed with anything else
what can be used to distinguish between pure things and mixtures
melting and boiling point data
in everyday language what does pure mean
a substance with nothing added - like pure milk
what is a formulation
a mixture designed as a useful product
how are formulations made
components mixed in carefully measured quantities to ensure the product has the required properties
give 5 examples of formulations
fuels
cleaning agent s
paints
medicines
alloys
fertilisers
food
what is chromatography for (2)
separate mixtures
help identify substances
what are the two phases in chromatography
stationary and mobile
what does separation depend on
the distribution of substances between stationary and mobile phases
what is the Rf value
distance moved by compound to distance moved by solvent
what is the distance moved by the compound as a distance
centre of spot from origin
different compounds have different R f values in different ___
solvents
a pure compound will produce ___spot in all solvents
a single
give a precaution of the chromatography practical
don’t get food colouring in eyes
what is limewater
calcium hydroxide
when CO2 is __or __through limewater it turns ___
bubbled through
shaken with
cloudy
what is the test for chlorine
damp litmus paper put into chlorine gas until bleached and turns white
what happens if the sample contains a mixture of ions in a flame test
the colours of the flames can be masked
what metal ions can flame tests identify
cations
what types of metal ions can sodium hydroxide be used to identify
cations
only ___precipitate dissolves in excess sodium hydroxide solution
aluminium hydroxide
what 3 ions form white precipitates when sodium hydroxide is added
aluminium
calcium
magnesium
what colour precipitates do copper II, ironII and iron III form in sodium hydorxide solution
blue
green
brown respectively
carbonate react with what to form carbon dioxide gas
dilute acids
how do halide ions produce precipitates - in what reaction
silver nitrate and dilute nitric acid
what colour is silver chloride
white
what colour is silver bromide
cream
what colour is silver iodide
yellow
sulfate ions produce a white precipitate when reacted with what
barium chloride
dilute hydrochloric acid
instrumental methdos are __ ___and __
accurate
sensitive
rapid
give an example of an instrumental method to analyse metal ions
flame emission spectroscopy
how does flame emission spectroscopy work
sample in flame
,light passed through a spectroscope
output is a line spectrum to identify metal ions and measure concentrations
