Experimental Techniques

Question 1

what equipment and unit do you use to measure time?

Answer 1

equipment - stopwatch
unit- seconds

Question 2

what equipment and unit do you use to measure mass?

Answer 2

equipment - electric balance/scale
unit - grams (standard unit is kg)

Question 3

what equipment and unit do you use to measure temperature?

Answer 3

equipment - thermometer
unit - ℃ (standard unit is K)

Question 4

what equipment and unit do you use to measure volume?

Answer 4

equipment - gas syringe/measuring cylinder/pipette/burette
unit - cm³ (1 cm³ = 1 ml)

Question 5

how do you read the volume of a liquid?

Answer 5

keep the meniscus at eye level.

Question 6

what are the different types of mixtures?

Answer 6

• solid+solid
• solid+liquid
• solid+gas (e.g. dust in the air)
• gas+gas (e.g. air)
• gas+liquid (fizzy/carbonated drinks)
• liquid+liquid

Question 7

examples of solid+solid mixtures?

Answer 7

• salt and pepper
• Fe powder and S powder

Question 8

types of solids in solid+liquid mixtures?

Answer 8

• soluble solids (e.g. salt and water)
• insoluble solids (e.g. sand and water)

Question 9

types of liquids in liquid+liquid mixtures?

Answer 9

• 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

Question 10

solute + solvent =?

Answer 10

solution

Question 11

examples of solutions?

Answer 11

• salt water
• sugar water
• rubbing alcohol

Question 12

what is filtration?

Answer 12

filtration is the process of separating insoluble solids from liquids/solutions.

Question 13

what is residue in filtration?

Answer 13

residue = the remains of the insoluble solid that goes through the filter paper.

Question 14

what is the filtrate in filtration?

Answer 14

filtrate = the liquid/solution that passes right through the filter paper

Question 15

filtration diagram (link because it won’t let me upload images, sorry)

Answer 15

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

Question 16

filtration method to separate sand from a mixture of sand and sugar?

Answer 16

• 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!!)

Question 17

what is solvent extraction?

Answer 17

a method to separate immiscible liquids.

Question 18

extra points of solvent extraction (about the solute)

Question 19

steps of solvent extraction?

Answer 19

• 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

Question 20

solvent extraction diagram (link because it won’t let me upload images, sorry)

Answer 20

take the right side diagram: https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSuthvOj6fuZ5Fow0POPP-v4B0rTqZFJlyrbw&s

Question 21

what is crystallisation?

Answer 21

crystallisation = a method of separating a soluble solid in a liquid.

Question 22

method to obtain CuSO₄ crystals from a CuSO₄ (aq) solution?

Answer 22

• 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.

Question 23

crystallisation diagram (link because it won’t let me upload images, sorry)

Answer 23

https://blogmedia.testbook.com/blog/wp-content/uploads/2022/08/crystallisation-668a7c93.png

Question 24

what is simple distillation?

Answer 24

simple distillation = a method to extract a liquid/solvent from a solution.

Question 25

simple distillation diagram (link because it won't let me upload images, sorry)

Answer 25

https://lh5.googleusercontent.com/iJ2cXJ-AeAW1Ku5EN4SfmJyKDz26BRi9EaMWaHMwY5KxX-d_x8u1SO2wfS6NBPeBqvSmDUQcZF75EE-xrSRmfVukZYyZYeQb1hxD9dnWTVIEOQ6RMNG1M96w6BZycT9QYBn9GEyU=w1200-h630-p-k-no-nu

Question 26

what is fractional distillation?

Answer 26

fractional distillation = a method used to separate miscible liquids that have close boiling points.

Question 27

why are glass beads used in fractional distillation?

Answer 27

* 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.

Question 28

what happens to the temperature while one component is being collected?

Answer 28

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.

Question 29

how do you heat the solution if certain components are flammable?

Answer 29

* using a hot water bath * using an electric heater

Question 30

fractional distillation diagram (link because it won't let me upload images, sorry)

Answer 30

sorry about the quality! it's the best one i can find: https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSeimRiIU0sD4dE_MGmnZ6F-udxXXc3bKa0kw&s

Question 31

what is **paper chromatography**?

Answer 31

a method used to separate substances and provide information to help identify them. the components have different solubilities in a given solvent.

Question 32

what do you need for a paper chromatography practical?

Answer 32

* jar/beaker * chromatography paper * stick * ethanol/water * mixture * capillary tube

Question 33

what is the **method** for a paper chromatography practical?

Answer 33

* 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 *

Question 34

Rf value equation

Answer 34

Rf = distance traveleld by substance ÷ distance travelled by solvent * colourless samples can be identified using locating agents

Question 35

paper chromatography diagram (link because it won't let me upload images, sorry)

Answer 35

https://mmerevise.co.uk/app/uploads/2022/11/TLC-e1669139515848-1024x863.png