Experimental Techniques Flashcards
what equipment and unit do you use to measure time?
equipment - stopwatch
unit- seconds
what equipment and unit do you use to measure mass?
equipment - electric balance/scale
unit - grams (standard unit is kg)
what equipment and unit do you use to measure temperature?
equipment - thermometer
unit - ℃ (standard unit is K)
what equipment and unit do you use to measure volume?
equipment - gas syringe/measuring cylinder/pipette/burette
unit - cm³ (1 cm³ = 1 ml)
how do you read the volume of a liquid?
keep the meniscus at eye level.
what are the different types of mixtures?
- solid+solid
- solid+liquid
- solid+gas (e.g. dust in the air)
- gas+gas (e.g. air)
- gas+liquid (fizzy/carbonated drinks)
- liquid+liquid
examples of solid+solid mixtures?
- salt and pepper
- Fe powder and S powder
types of solids in solid+liquid mixtures?
- soluble solids (e.g. salt and water)
- insoluble solids (e.g. sand and water)
types of liquids in liquid+liquid mixtures?
- miscible liquids (e.g. alcohol and water)
- immiscible liquids (e.g. oil and water)
miscible liquid = a liquid able to dissolve completely in another liquid
solute + solvent =?
solution
examples of solutions?
- salt water
- sugar water
- rubbing alcohol
what is filtration?
filtration is the process of separating insoluble solids from liquids/solutions.
what is residue in filtration?
residue = the remains of the insoluble solid that goes through the filter paper.
what is the filtrate in filtration?
filtrate = the liquid/solution that passes right through the filter paper
filtration diagram (link because it won’t let me upload images, sorry)
https://www.shutterstock.com/shutterstock/photos/2296554021/display_1500/stock-vector-filtration-process-simple-filtration-diagram-solid-residue-glass-funnel-filter-paper-and-2296554021.jpg
filtration method to separate sand from a mixture of sand and sugar?
- add water to the mixture and mix
- filter the solution with filter papers, a funnel and a conical flas
- extract the residue (sand)
- wash residue (sand) with distilled water or an organic solvent
- dry between filter papers or and oven (oven for sand specifically!!)
what is solvent extraction?
a method to separate immiscible liquids.
extra points of solvent extraction (about the solute)
steps of solvent extraction?
- add the aqueous layer into the separating funnel
- add the organic layer into the separatiing funnel
- mix thoroughly, releasing pressure periodically
- leave the two layers to settle
- take ine layer out through the separation funnel
solvent extraction diagram (link because it won’t let me upload images, sorry)
take the right side diagram: https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSuthvOj6fuZ5Fow0POPP-v4B0rTqZFJlyrbw&s
what is crystallisation?
crystallisation = a method of separating a soluble solid in a liquid.
method to obtain CuSO₄ crystals from a CuSO₄ (aq) solution?
- heat in an evaporation dish, using a bunsen burner until crystallisation point is reached
- leave to cool
- filter the crystals
- wash the crystals in cool distilled water or an organic solvent
- dry between filter papers
oven drying does not work for temperature-sensitive compounds as the compound may decompose or become dehydrated.
crystallisation diagram (link because it won’t let me upload images, sorry)
https://blogmedia.testbook.com/blog/wp-content/uploads/2022/08/crystallisation-668a7c93.png
what is simple distillation?
simple distillation = a method to extract a liquid/solvent from a solution.
simple distillation diagram (link because it won’t let me upload images, sorry)
https://lh5.googleusercontent.com/iJ2cXJ-AeAW1Ku5EN4SfmJyKDz26BRi9EaMWaHMwY5KxX-d_x8u1SO2wfS6NBPeBqvSmDUQcZF75EE-xrSRmfVukZYyZYeQb1hxD9dnWTVIEOQ6RMNG1M96w6BZycT9QYBn9GEyU=w1200-h630-p-k-no-nu
what is fractional distillation?
fractional distillation = a method used to separate miscible liquids that have close boiling points.
why are glass beads used in fractional distillation?
- so that the component with a higher boiling point condenses in the glass beads and returns to the mixture for more efficient separation.
- the glass beads also provide a larger surface area for condensation.
what happens to the temperature while one component is being collected?
it remains the same until the component is distillate and collected, then increases to the boiling point of the next component.
same concept as heating curves.
how do you heat the solution if certain components are flammable?
- using a hot water bath
- using an electric heater
fractional distillation diagram (link because it won’t let me upload images, sorry)
sorry about the quality! it’s the best one i can find: https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSeimRiIU0sD4dE_MGmnZ6F-udxXXc3bKa0kw&s
what is paper chromatography?
a method used to separate substances and provide information to help identify them. the components have different solubilities in a given solvent.
what do you need for a paper chromatography practical?
- jar/beaker
- chromatography paper
- stick
- ethanol/water
- mixture
- capillary tube
what is the method for a paper chromatography practical?
- take the chromatography paper and draw your solvent line and base line using a pencil (pen will also start to separate)
- put a drop of the mixture onto your baseline using the capillary tube
- fill your beaker with the solvent in such a way that the solvent does not touch the base line
- roll the paper around the stick in order to place it securely in the beaker
- place it in the beaker and take it out once the solvent reaches the solvent line
- analyse the sample using Rf values
*
Rf value equation
Rf = distance traveleld by substance ÷ distance travelled by solvent
- colourless samples can be identified using locating agents
paper chromatography diagram (link because it won’t let me upload images, sorry)
https://mmerevise.co.uk/app/uploads/2022/11/TLC-e1669139515848-1024x863.png
