C2 experimental techniques Flashcards
Describe Chromatography
A method of separating mixtures of soluble substances
Describe mixture
contains 2 or more substances not chemically combined
Describe Solvent
a substance that dissolves a solute
Describe stationary phase in chromatography
the paper in paper chromatography
Describe mobile phase in chromatography
the solvent in paper chromatography
Describe chromatogram
shows the results of separating the components of a mixture by chromatography
Describe impure substance
made of more than one thing and produces two or more spots on a chromatogram
Describe Rբ value
A way of measuring how far a spot has travelled on a chromatogram compared to the distance the solvent has travelled
Solvent front
the furthest point the solvent travels in paper chromatography
describe solute
a substance that is able to dissolve in a solvent
describe pencil line
doesn’t dissolve in the solvent so can be used as a baseline to make measurements in paper chromatography
What types of separation techniques are there? [4]
-Filtration
-Chromatography
-Crystallisation
-fractional/simple distillation
Describe Filtration [4]
-separates mixtures of insoluble solids and liquids
-by pouring mixture through filter paper
+solid trapped
+liquid run through
Describe Crystallisation [5]
-separates solutions into their contituent(different) parts
-solutes and solvents
-by heating the mixture so that the solvent evaporates
+crystal solutes
+collected solvent by condensing as it evaporates
Describe Fractional distillation
separates liquids with different boiling points
-mixture heated until the liquid with lowest boiling point boils and condenses
-increase temperatuer to collect the other fractions
Describe simple distillation
separates 2 liquids with different boiling points
-mixture heated until the liquid with lower boiling point boils
-vapour passes through condenser and cools to liquid
What equipment is used to measure time and what is the unit?
stopwatch, seconds
what equipment is used to measure temperatuer and what is the unit?
thermometer, degrees celsius
what equipment is used to measure mass and what is the unit?
Mass balance, grams
What 3 equipments are used to measure volume of liquid and what is the unit?
-measuring cylinder, volumetric pipette, burette
-cm3
what equipment is used to measure volume of gas and what is the unit?
gas syringe, cm3
what process is used to seperate two or more solids that are soluble?
Paper chromatography
define pure substance
a substance that contains a single element or comound not mixed with any other substance
How do you calculate Rf values in paper chromatography?
Distance moved by solute/distance moved by solvent (solvent front)
describe 3 ways that the purity of a substance can be assessed
melting point, boiling point, chromatography
Describe how melting point/boiling point can be used to assess purity
pure - exact melting/boiling point
impure - range of melting/boiling point
describe how chromatography can be used to assess purity
pure-only produce only one well defined spot on a chromatogram
describe two examples of where purity of substances is important [2]
manufacture of compounds used in drugs food additives
describe solution
liquid mixture composed of two or more substances
define volatility
How easily a substance evaporates/changes from a liquid to a gas
define solubility
How easily a substance dissolves
what is the filtrate in filtration
the liquid or solution that has passed through the filter
What is distillation used for
to seperate a solvent from a solution
How do you get a pure dry substance?
-isolate the substance
-dissolve it in water (dissolves soluble impurities)
-Evaporate the water
