C12: Chemical Analysis Flashcards
what is a pure substance?
single element or compound, not mixed with any other substance
how do you know its a pure substance?
melt/boil at specific temps
- mixtures have range of MPs and BPs
what is a formulation?
mixture that has been desiged as a useful product
- made my mixing components in carefully measured quanities to ensure product has required properties
examples of formulations ?
fuels, cleaning agents , paints amnd medecines
process of chromotography?
- pencil line drawn on chromotography paper/ spots of sample placed on it
- paper lowered into solvent , making sure pencil line is above solvent
- different substance have differnt solubility so travel at different rates (high solubility-travel further)
how can u identify if substance is pure or not from chomotography?
pure substance only has one spot on chromotogram
- mixtures have multiple
how to calculate Rf value?
distance moved by substance/distance moved by solvent
flame test for
Lithium?
crimson
flame test for
sodium
yellow
flame test for
potassium
lilac
flame test for
calcium
orange-red
flame test for
copper
green
effect of adding metal NaOH to
aluminium. calcium, magnesium
white precipitate
(only aluminium’s precipitate dissolves when excess NaOh is added)
effect of adding metal NaOH to
copper
blue precipitate
effect of adding metal NaOH to
iron II/iron III
iron II - green precipitate
iron III - brown precipitate
test for carbonates?
carbonates will react with dilute acids - create CO2
- gas can be bubbled through limewater to test for CO2
test for halides and results?
cats with brains can ideally yodel
- add dilute nitric acid and silver nitrate solution
CHLORIDE - white precipitate
BROMIDE - Cream precipitate
IODINE - yellow precipitate
test for sulfates?
first add dilute Hcl , followed by barium chloride solution
- if sulfate ions are present, white pecipitate forms
what do instrumental methods do and advantages?
detect/identify elements and compounds
- accurate
- sensitive/rapid
what is flame emission spectroscopy?
instrumental method to analyse metal ions in solutions
- sample put into flame / light given out (due to electrons fallng back to energy levels) is passed through spectroscope
- results in line spectrum that can be analysed to identify metal ions/measure concentrations
test for hydrogen, oxygen and chlorine?
HYDROGEN : burning splint held at open end of test tube of gas , pops
OXYGEN : glowing splint inserted into test tube of gas
- splint relights - O2
CHLORINE : damp litmus paper bleaches /turns white if present
describe the the design and general properties of a formulation?
4mks
formulations are mixture designed to be useful products.
- measured quantities of components used
- each component has purpose
- giving mixture desired properties
how does chromotography seperate dyes?
- solvent moves through paper
- different dyes have different solublities in solvent
- and different attrcations for the paper
- so carried different distances
