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Chemistry > Paper 1 Practicals > Flashcards

Paper 1 Practicals Flashcards

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1
Q

What is a salt?

A
  • contain a positive ion
  • contains a negative ion
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2
Q

How do you make crystals from a soluble salt?

A
  • Place a bunsen burner on top of a heatproof mat. Place a tripod with gauze and a breaker on top.
  • Gently heat a fixed volume of Sulfuric acid within the beaker until almost boiling
  • Use a spatula to add small amount of Copper Oxide to the solution, then stir in with a glass rod. The CuO should seem to disappear and the solution will turn a blue colour
  • Keep adding CuO until some powder remains in the blue solution (shows the reactant has stopped, acid has stopped reacting)
  • Use a funnel with filter paper and a conical flask to filter the insoluble CuO, leaving the filtrate (CuSO4)
  • Place the copper sulfate solution in an evaporating basin and heat it gently over a beaker of boiling water.
  • Leave the solution in a cool place for the Copper Sulfate crystals to form
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3
Q

What is a limiting reactant?

A

The reactant in a reaction that runs out first

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4
Q

What is a titration?

A

The solution of a known concentration is used to find the concentration of an unknown solution

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5
Q

What is the method of Titration?

A
  • Use a pipette to transfer 25cm3 of an alkali into a conical flask
  • Add 5 drops of an indicator (methyl orange etc) to the alkali
  • Place conical flask on a white tile (see changed more clearly)
  • Fill a biuret with acid
  • Add just enough acid to the alkali until it is neutral
  • Once a colour change occurs, add acid in drop by drop until the solution is neutral
  • swirl the mixture to make sure the acid and alkali mix
  • read volume of acid added from the biuret
  • repeat the experiment until you get and overall 3 concordant results, take a mean for final volume (increases accuracy)
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6
Q

Titration: What will the colour change be for Methyl Orange?

A

Orange-> Red

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7
Q

Titration: How do you read from a biuret?

A
  • eye is level with the surface of the liquid
  • read from the bottom of the meniscus
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8
Q

What does concordant results mean?

A

Within 0.2 cm3 of each other

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9
Q

How do you investigate the effect on Aqueous solutions when undergoing electrolysis?
(Copper II Chloride)

A

1- pour 50cm3 of Copper II Chloride solution into a beaker
2- place a plastic petri dish over the beaker, with 2 holes
3- insert carbon graphite rods into each of the holes (electrodes)
4- connect wires to the rods with crocodile clips, connecting them to a low-voltage battery pack (4V, switch on)
5- cathode (-ve) is coated with copper, less reactive than hydrogen-> discharged at the cathode
6- anode: bubbles of gas, smell of chlorine-> halogen = discharged at anode
7-

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10
Q

What does inert mean?

A

unreactive

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11
Q

Why must the electrodes not touch?

A

It would produce a short circuit

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12
Q

Copper II Chloride: If you hold a piece of damp blue litmus paper near the anode what happens?

A

The anode is producing chlorine gas so bleaches the paper. (proves gas is chlorine)

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13
Q

How do you investigate the effect on Aqueous solutions when undergoing electrolysis?
(Sodium Chloride solution)

A

1- pour 50cm3 of Sodium Chloride solution into a beaker
2- place a plastic petri dish over the beaker, with 2 holes
3- insert carbon graphite rods into each of the holes (electrodes)
4- connect wires to the rods with crocodile clips, connecting them to a low-voltage battery pack (4V, switch on)
5- anode (+ve): bubbles of gas, bleaches litmus paper= chlorine (Halide, halogen discharged at the anode)
6- cathode (-ve): bubbles of gas, hydrogen. Sodium is MORE reactive, hydrogen is discharged at cathode. Use lit splint, squeaky pop test

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14
Q

How do you investigate the temperature change of an exothermic reaction?
(Neutralisation reaction-> NaOH + HCL)

A

1- use a measuring cylinder 30cm^3 of dilute HCL
2- transfer the acid into a polystyrene cup
3- Stand the polystyrene cup inside the beaker, stopping the cup from falling over
4- Use thermometer to measure temp of the acid, record data
5- use a measuring cylinder to measure 5cm^3 of Sodium Hydroxide solution, transfer to polystyrene cup
6- Fit plastic lid to cup with hole, place thermometer through hole (bulb must be submerged in the solution), gently stirring the solution.
7- exothermic reaction, temperature will increase, record highest temp reached
8- Rinse cup and repeat experiment
9- repeat again twice with 10cm^3 of Sodium Hydroxide solution
10- repeat several more times, each time increases amount of Sodium Hydroxide by 5cm^3 until max of 40cm^3, 2 results for each volume of NaOH
11- calculate mean value for max temp reached for each volume, then plot graph of results

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15
Q

What is the Independent, Control and Dependant variables of a Neutralisation reaction of NaOH and HCL?

A

Independent: Volume of Sodium Hydroxide solution
Dependant: Maximum temperature reached
Control: Volume of HCL, Concentration of both solutions

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16
Q

What is the relationship between temperature reached and volume of NaOH?

A

As volume increases, temperature increases as if there are more Sodium Hydroxide particles, there will be more reactions with the HCL particles
HOWEVER, at a certain point of adding NaOH, the max temp starts to decrease, as there is TOO much NaOH and not is HCl to react (some NaOH is unable to react.)

17
Q

Why does maximum temperature begin to decrease at a certain volume of NaOH?

A

Energy released is spread over a larger volume, so when there is large volumes of NaOH, max temp decreases

18
Q

Temp change: Why do you use a polystyrene cup with a lid?

A

Polystyrene is a good thermal insulator, reduced heat loss
Lid reduced heat loss to the air

19
Q

How do you explain the method of filtration?

A
  • Cut a piece of filter paper into a circle, then cut a small triangle into the paper so you can fold it into a cone
  • Use a folded filter paper cone and place it in the funnel
  • pour solution containing insoluble solid into the filter paper, separating the liquid reaction mixture from the solid.
19
Q

How do you explain the Method of Evapouration?

A
  • Pour solution into evaporating dish
  • slowly heat the solution-> the solvent will evaporate and solution becomes more concentration, eventually crystals form
  • keep heating until liquids have evaporated and only dry crystals are left
20
Q

How do you explain the Method of Crystallisation?

A

-Pour solution into an evaporating dish and gently heat solution -> solvent will evaporate and solution becomes more concentrated
- When crystals begin to form, remove the dish from the heat and leave the solution to cool
- Salt begins to form crystals, insoluble in the cold
- Filter crystals out of solution, leave in warm place to dry (eg drying oven, in the sun)

21
Q

What is Rock salt?

A

A mixture of salt and sand

  • used on the roads in the winter
22
Q

How can you seperate Rock salt?

A

Using Filtration and Crystallisation

  • Grind the mixture (salt crystals are small), so it dissolves easy
  • Put mixture in water and stir (salt dissolves, sand doesn’t)
  • Filter mixture, collect sand on paper and solution (containing salt) in beaker
  • Evaporate water from salt, creates dry crystals
23
Q

What is distillation?

A

A separating process used to seperate mixtures containing liquids

24
Q

How do you explain the process of Simple Distillation?

A
  • Heat the solution, part of the solution with the lowest Boiling point evapourates first
  • Vapour rises and then is cooled and condensed in the condenser, where it turns back into a liquid and is recollected
  • Rest of the solution is left behind in the flask
  • Saltwater-> seperate water and salt
  • Can only use for substances with very different boiling points, otherwise will mix again as vapour.
25
Q

How do you explain the process of Fractional Distillation?

A

Used to seperate a mixture of multiple liquids

  • Place mixture in a flask with a fractioning column on top, then heat it up
  • different liquids have different boiling points so evaporate at different temperatures (Lowest BP evaporates first)
  • When the temp on the thermometer matches its BP, it reaches the top of the column, it is condensed in the condenser and collected
  • Liquids with higher BP may also being to evaporate, but will condense before reaching the top as it gets colder further up the fractioning column
  • When the first liquid is fully collected, raise the temperature until the next one reaches the top.

Chemistry (13 decks)

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