paper 1 practical Flashcards
Making soluble salts
- Instruments - Beaker, tricolon, heatproof and heatproof mat
1- Add fixed amount of dilute sulfuric acid (limiting reatant so don’t contaminate salt)
2- Gently heat acid until almost boiling
3- Use spatula, to add small amounts of copper oxide
4- Stir solution using glass rod
5- Copper oxide will react and seem to disappear
6- Continue adding copper oxide if the solution continues to be clear blue
7- Stop adding copper oxide if some powder remains after stirring
8- At this point reaction has stopped as all of acid has reacted
9- Use filtration to remove the copper oxide
10- Place solution in an evaporation basin,
Heat gently over a boiling water
11- Heat until around half of the solution remains .
Titrations
- 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
Electrolysis Copper chloride solution
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
Electrolysis Sodium chloride solution
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
Temperature change variables
- 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
Temperature change
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
