Chemistry Flashcards
RP 1:
Aim:
RP 1:
To prepare a pure, dry sample of a soluble salt from an insoluble oxide or
carbonate.
(using a Bunsen burner to heat dilute acid and a water bath or electric heater to evaporate the solution)
RP 1:
What equipment does this practical require?
RP 1:
● 1.0 M dilute sulfuric acid ● Copper (II) oxide powder ● A spatula ● A glass rod ● A measuring cylinder ● Two beakers: one 100 cm^3 and one 250 cm^3 ● Bunsen burner ● Tripod ● Gauze ● Heatproof mat ● Filter funnel and paper ● A small conical flask ● An evaporating basin ● A crystallising dish
RP 1:
What’s the First step of making salts?
RP 1:
- Measure 20 cm^3 sulfuric acid into a measuring cylinder and pour it into beaker
RP 1:
What’s the Second step of making salts?
RP 1:
- Heat the acid gently using a Bunsen burner
RP 1:
What’s the Third step of making salts?
RP 1:
- Add small amounts of insoluble base in this case copper oxide in excess (until no more reacts thus no more effervescence is produced)
RP 1:
What’s the Fourth step of making salts?
RP 1:
- Filter using filter paper and funnel the solution to remove the excess copper oxide
RP 1:
What’s the Fifth step of making salts?
RP 1:
- Pour the solution into the evaporating basin
RP 1:
What’s the Sixth step of making salts?
RP 1:
- Evaporate the solution using a water bath until crystals start to form
RP 1:
What’s the Seventh step of making salts?
RP 1:
- Leave the evaporating basin in a cool place for at least 24 hours
RP 1:
What’s the Eighth step of making salts?
RP 1:
- Gently pat the crystals dry between two pieces of filter paper
RP 1:
Safety Precautions:
RP 1:
● Wear safety goggles as sulphuric acid is corrosive.
● Make sure hair is tied back.
● When the Bunsen burner is not in use, turn it off or leave it on the orange safety flame
RP 1:
How could you prepare a sample of pure, dry copper sulfate crystals from a sample of insoluble copper oxide?
RP 1:
- React sulfuric acid with excess copper oxide
- Filter to remove the excess copper oxide
- Heat the solution to start evaporation
- Turn off the heat and leave until all of the water has evaporated
- Left with copper sulfate crystals
RP 1:
What are two methods of separating mixtures?
RP 1:
Filtration, Crystallisation
RP 1:
Magnesium and dilute hydrochloric acid react to produce magnesium chloride
solution and hydrogen.
Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)
(i) State two observations that could be made during the reaction.
RP 1:
effervescence / bubbling / fizzing / bubbles of gas
RP 1:
Outline a suitable method for obtaining a sample of pure, dry salt crystals:
RP 1:
- Measure 20 cm3 sulfuric acid into a measuring cylinder and pour it into beaker
- Heat the acid gently using a Bunsen burner
- Add small amounts of insoluble base in this case copper oxide in excess (until no more reacts thus no more effervescence is produced)
- Filter using filter paper and funnel the solution to remove the excess copper oxide
- Pour the solution into the evaporating basin
- Evaporate the solution using a water bath until crystals start to form
- Leave the evaporating basin in a cool place for at least 24 hours
- Gently pat the crystals dry between two pieces of filter paper
RP 2:
What is neutralisation?
- what does is result in
RP 2:
The reaction between an acid and a base
- Forms a neutral solution of a salt and water (Acid + Alkali → Salt + Water)
RP 2:
Aim:
RP 2:
To find the concentration of a dilute sulfuric acid solution, using a sodium hydroxide solution of known concentration
RP 2:
What equipment does this practical require?
RP 2:
● 25 cm^3 volumetric pipette ● Pipette filler ● 50 cm^3 burette ● 250 cm^3 conical flask ● Small funnel ● Clamp stand and clamp ● White tile ● 0.1 M sodium hydroxide solution ● Sulfuric acid ● Phenolphthalein indicator
RP 2:
What’s the First Step of performing a titration?
RP 2:
- Use the pipette to measure 25cm^3 of sodium hydroxide into the conical flask
RP 2:
What’s the Second Step of performing a titration?
RP 2:
- Place the conical flask on a white tile.
RP 2:
What’s the Third Step of performing a titration?
RP 2:
- Fill the burette with sulphuric acid using a funnel
RP 2:
What’s the Fourth Step of performing a titration?
RP 2:
- Record the initial reading of acid in the burette
- Make sure to always take readings from the bottom of the meniscus
RP 2:
What’s the Fifth Step of performing a titration?
RP 2:
- Add a 5 drops of indicator in this case phenolphthalein to the conical flask
RP 2:
What’s the Sixth Step of performing a titration?
RP 2:
- Slowly open the burette tap while swirling the conical flask
RP 2:
What’s the Seventh Step of performing a titration?
RP 2:
- Add acid drop-by-drop near the endpoint
- At this point the colour will start to change slightly
RP 2:
What’s the Eighth Step of performing a titration?
RP 2:
- Close the burette when a colour change occurs in phenolphthalein
- The solution turns from pink to colourless
RP 2:
What’s the Ninth Step of performing a titration?
RP 2:
- Record the final reading of acid in the burette and calculate the titre
- This is the volume of acid used to neutralise the alkali
RP 2:
What’s the Tenth Step of performing a titration?
RP 2:
10. Repeat until you have concordant results
These are within 0.1cm3 of each other
RP 2:
What’s the Eleventh Step of performing a titration?
RP 2:
- Present results in a table and calculate the mean titre discarding any anomalies when calculating the mean
RP 2:
What’s the Twelfth Step of performing a titration?
RP 2:
- Calculate the number of moles of sodium hydroxide used in the titration by looking at the balanced symbol equation for the reaction
RP 2:
What’s the Thirteenth Step of performing a titration?
RP 2:
- Work out the concentration of sulphuric acid using the formula (concentration= moles/volume)
RP 2:
Safety Precautions:
RP 2:
● Wear safety goggles when working with acids
● Tie hair back
● Report any broken glassware immediately
RP 2:
Outline a suitable method that could be used to perform a titration:
RP 2:
- Use the pipette to measure 25cm3
of sodium hydroxide into the conical flask. - Place the conical flask on a white tile.
- Fill the burette with sulphuric acid using a funnel.
- Record the initial reading of acid in the burette.
- Make sure to always take readings from the bottom of the meniscus. - Add a 5 drops of indicator in this case phenolphthalein to the conical flask.
- Slowly open the burette tap while swirling the conical flask.
- Add acid drop-by-drop near the endpoint.
- At this point the colour will start to change slightly. - Close the burette when a colour change occurs in phenolphthalein.
- The solution turns from pink to colourless. - Record the final reading of acid in the burette and calculate the titre
- Repeat until you have concordant results
(These are within 0.1cm3 of each other) - Present results in a table and calculate the mean titre discarding any anomalies when calculating the mean
- Calculate the number of moles of sodium hydroxide used in the titration by looking at the balanced symbol equation for the reaction
- Work out the concentration of sulphuric acid using the formula (concentration= moles/volume)
RP 2:
Why is a single indicator used rather than universal indicator?
RP 2:
Because the end point needs to be observed by a sudden colour change
RP 2:
Why should a white tile be used in a titration reaction?
RP 2:
It makes the colour change in the reacting mixture easier to see.
RP 2:
What colour is phenolphthalein in acid and alkali?
RP 2:
Acid - Colourless
Alkali - Pink
RP 2:
What colour is Litmus in acid and alkali?
RP 2:
Acid - Red
Alkali - Blue
RP 2:
What colour is Methyl Orange in acid and alkali?
RP 2:
Acid - Red
Alkali - Yellow
RP 2:
Neutralisation reactions are exothermic.
Suggest what this means in terms of energy transfer:
RP 2 :
An exothermic reaction involves energy being transferred from the reacting chemicals to the surroundings. They can be shown by a rise in temperature
RP 2:
Sulfuric acid is a strong acid.
What is meant by a strong acid?
RP 2:
Sulfuric acid is completely ionised in aqueous solution // when dissolved in water
RP 4:
Aim:
RP 4:
To investigate the variables that affect temperature change during chemical reactions
RP 4:
What equipment does this practical require?
RP 4:
● 2 M hydrochloric acid
● 2 M sodium hydroxide solution
● Expanded polystyrene cups and lids with thermometer holes
● Thermometers
RP 4:
Outline a suitable method for testing the effect of acid concentration on the energy released during a neutralisation reaction between hydrochloric acid and sodium hydroxide:
RP 4:
1) Put 25 cm^3 of 0.25 mol/dm^3 HCl and NaOH in separate beakers
2) Place both beakers in a water bath set to 25ºC, until they both reach 25ºC
3) Add the HCl followed by the NaOH to a polystyrene cup with a lid
4) Take the temperature of the mixture every 30 seconds, and record the highest temperature
5) Repeat steps 1-4 using 0.5 mol/dm^3 and then 1 mol/dm^3 of hydrochloric acid
RP 4:
What is the First Step in an experiment investigating variables affecting temperature changes?
RP 4:
1)Put 25 cm^3 of 0.25 mol/dm^3 HCl and NaOH in separate beakers
RP 4:
What is the Second Step in an experiment investigating variables affecting temperature changes?
RP 4:
2)Place both beakers in a water bath set to 25ºC, until they both reach 25ºC
RP 4:
What is the Third Step in an experiment investigating variables affecting temperature changes?
RP 4:
3)Add the HCl followed by the NaOH to a polystyrene cup with a lid
RP 4:
What is the Fourth Step in an experiment investigating variables affecting temperature changes?
RP 4:
4)Take the temperature of the mixture every 30 seconds, and record the highest temperature
RP 4:
What is the Fifth Step in an experiment investigating variables affecting temperature changes?
RP 4:
5)Repeat steps 1-4 using 0.5 mol/dm^3 and then 1 mol/dm^3 of hydrochloric acid
RP 4:
Safety Precautions:
RP 4:
● Wear safety goggles
RP 4:
How could the amount of energy lost to the surroundings be reduced?
RP 4:
- Mix the reactants in a polystyrene cup
- Place the polystyrene cup in a beaker of cotton wool
- Keep a lid on the cup to reduce energy loss through evaporation
RP 4:
Why should both chemicals start at the same temperature?
RP 4:
To ensure that their individual temperatures do not have an effect on the temperature recorded once combined
RP 4:
Why is it important to stir the mixture when taking a temperature reading?
RP 4:
- To ensure that the temperature is consistent throughout the mixture
- To ensure that the reactants have fully reacted
RP 4:
How could the temperature be measured more precisely?
RP 4:
By using a digital thermometer
RP 4:
How could the temperature be measured more reliably?
RP 4:
By repeating the experiment and calculating a mean temperature measurement
RP 4:
What variables must be controlled during this experiment?
RP 4:
- Alkali concentration
- Alkali volume
- Acid volume
- Initial temperatures of each reactant
- External temperatures