paper 1 practical Flashcards

(6 cards)

1
Q

Making soluble salts

A
  • Instruments - Beaker, tricolon, heatproof and heatproof mat

Measure a fixed volume of dilute sulfuric acid using a measuring cylinder and pour it into a beaker.

Gently heat the acid using a Bunsen burner until it is nearly boiling. Then turn off the flame. (Do not boil vigorously – avoid acid spitting.)

Add copper(II) oxide a little at a time using a spatula and stir with a glass rod.

Continue adding copper oxide until it is in excess (i.e. some remains after stirring). This ensures all the acid has reacted.

Filter the mixture using filter paper and a funnel to remove the unreacted copper oxide.

Pour the filtrate (blue solution) into an evaporation basin.

Heat the solution gently over a beaker of boiling water until half the water has evaporated. (Don’t evaporate to dryness.)

Leave the solution to cool slowly so copper sulfate crystals form.

Dry the crystals by patting them gently with filter paper.

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2
Q

Titrations

A
  • Equipment – Alkali, pipette, conical flask

1- Use a pipette and transfer 25cm^3 of sodium hydroxide solution to a conical flask

2- Add five drops of a indicator such as phenolphthalein to the alkali in the conical flask

3- Place conical flask on white tile so we can see a colour change more clearly

4- Fill a burettes with sulfuric acid

5- Add acid to alkali until solution is neutral. We need to add just enough acid for this to happen.
Once we start to see a colour change, we now add drop by drop until the solution is neutral
It is important to swirl the solution to make sure the acid and alkali mix

6- Read the volume of acid added from burette

7- Use these to calculate concentration

Other ideas

– conical flask reduces risk of splashing

  • When reading from burette make sure you read from surface of the liquid (surface naturally curve) meniscus
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3
Q

Electrolysis Copper chloride solution

A

1- First we pour approximately 50 cm^3 of copper (II) chloride solution into a beaker

2- We place a plastic petri dish above beaker

3- Petri dish should have two holes

4- Insert a carbon graphite rod into each hole (these are electrodes)

5- Carbon graphite is unreactive, so electrodes are inert (electrodes must not touch each other because it would produce a short circuit)

6- Connect rods to terminals of low voltage power supply (select 4 volts)

7- Negative electrode (cathode coated with copper)

8- Chlorine gas produced at anode (positive electrode)

9- If we hold a piece of samp blue litmus paper it becomes bleached proving gas is chlorine

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4
Q

Electrolysis Sodium chloride solution

A

1- Place 50cm^3 of sodium chloride solution into the beaker

2- Just like before turn on low power supply

3- Gas produced at anode (positive electrode), test using blue litmus paper should be bleached so chlorine

4- Hydrogen gas discharged at cathode since sodium more reactive than hydrogen

5- Can test by collecting it and test it with a lit splint producing a squeaky pop

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5
Q

Temperature change variables

A
  • Independent variable is volume of sodium hydroxide
  • Dependent variable is maximum temperature reached
  • Control variables are volume of hydrochloric acid and concentration of hydrochloric and the sodium hydroxide solution
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6
Q

Temperature change

A

1- Start by using measuring cylinder and measuring 30cm^3 of dilute hydrochloric acid

2- We then transfer acid to polystyrene cup

3- We stand polystyrene cup inside a beaker (stops cup from falling over

4- Use thermometer to measure temperature of the acid (record this in a table)

5- We use a measuring cylinder to measure 5cm^3 of sodium hydroxide solution

6- Transfer to polystyrene cup

7- Put plastic lid on cup and place thermometer through hole in lid (bulb of thermometer must be In a solution

8- Use thermometer to gently stir solution

9- Exothermic so temperature of solution will increase
When reading on thermometer stops changing we record highest temperature reached

11- Rinse out and dry polystyrene cup

12- Repeat experiments using 10cm^3 of sodium hydroxide solution

13- carry out experiments several more times with each time increasing volume of solution by 5 cm^3

14- Until we reach a maximum of 40cm^3 of sodium hydroxide solution

15- Repeat experiment one more time to get means of results

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