Leah Firmstone
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Quiz on Required Practicals for AQA A Level Chemistry INCOMPLETE, created by Leah Firmstone on 24/04/2017.

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Leah Firmstone
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Required Practicals for AQA A Level Chemistry INCOMPLETE

Question 1 of 15

1

Making up a standard solution
Stage 1: transferring a mass of the solid
• Weigh the solid into a weighing boat recording the mass (to appropriate precision).
• Transfer the solid to a .
• Re-weigh the weighing boat and record the in mass.
Stage 2: dissolving the solid in distilled water
• Add the distilled water to the beaker to dissolve.
• Stir the beaker with the until the solid has dissolved.
Stage 3: rinsing all glassware and making up the solution
• Transfer the solution to a using a funnel.
• Rinse all used glassware into the volumetric flask (glass rod, beaker and ).
• Add water up to the (on the volumetric flask).
the flask several times.

Drag and drop to complete the text.

    beaker
    difference
    known
    minimum
    glass rod
    volumetric flask
    distilled
    graduation line
    funnel
    Invert

Explanation

Question 2 of 15

1

Which of the following should you NOT do when making up a standard solution?

Select one of the following:

  • Weigh the weighing boat with the solid in it, and then again after the solid has been transferred to a beaker.

  • Invert the volumetric flask before using the solution.

  • Add distilled water to just above the graduation line, then use a dropping pipette to remove the extra.

Explanation

Question 3 of 15

1

Any glassware that has been in contact with the solution should be rinsed into the volumetric flask when making up a standard solution.

Select one of the following:

  • True
  • False

Explanation

Question 4 of 15

1

Carrying out an acid-base titration
Stage 1: Preparing the conical flask
• Using a , transfer the desired amount of the acidic solution into the conical flask.
• Add several drops of an appropriate to the conical flask.
• Rinse any solution on the sides of the flask into the flask with .
Stage 2: preparing the burette
• Fill the burette up with the basic solution using a .
• Run the solution through the jet, ensuring that there are no present.
• Remove the funnel from the burette.
Stage 3: performing the titration
• Place the conical flask on a beneath the burette.
• Record the starting volume of the burette.
• Titrate the solution, swirling the until a colour change is observed.
• Record the end volume in the and calculate the titre.
• Repeat until results (titre values within 0.1 cm³ of each other) are achieved and calculate a mean titre (never include values).

Drag and drop to complete the text.

    glass pipette
    indicator
    distilled water
    conical flask
    permanent
    funnel
    air bubbles
    concordant
    burette
    white tile
    rough

Explanation

Question 5 of 15

1

Using distilled water to rinse the sides of the conical flask in an acid-base titration will negatively affect your results.

Select one of the following:

  • True
  • False

Explanation

Question 6 of 15

1

Why do you remove the funnel from the burette during a titration?

Select one of the following:

  • So that any remaining droplets of solution do not fall into the burette and so change the volume/titre value.

  • To stop you knocking it out/it falling out when adjusting the clamp to allow you to read the meniscus.

  • So that it can be used by another group.

Explanation

Question 7 of 15

1

Which of the following is NOT a suitable indicator for use in ANY titration?

Select one of the following:

  • Potassium permanganate solution

  • Methyl orange solution

  • Universal indicator solution

Explanation

Question 8 of 15

1

Experimentally finding the enthalpy change of combustion
Stage 1: preparing the chemicals
• Add the fuel to the and record the initial mass.
• Add a known quantity of water to the and clamp in position above the spirit burner.
• Use thermometer to measure the initial temperature of the .
Stage 2: carrying out the experiment
• Use the spirit burner to heat water in the calorimeter to roughly (40ᵒC) and record the .
• Reweigh the spirit burner and calculate the of the fuel.
Stage 3: interpreting the results
• Calculate the energy released () using the equation q = mcΔT where q = ; m = mass of water heated; c = (4.18); ΔT = change in temperature.
• Calculate the enthalpy change () using the equation ΔH = q / (moles of fuel).
• Convert into by dividing your answer by 1000.

Drag and drop to complete the text.

    spirit burner
    calorimeter
    water
    temperature change
    change in mass
    J
    Jmol⁻1
    kJmol-1
    specific heat capacity of water
    energy change

Explanation

Question 9 of 15

1

Why are data book values often higher than those calculated experimentally?
(CHOOSE 4)

Select one or more of the following:

  • Heat is lost to the surroundings, meaning the temperature change is smaller than it should be and so the enthalpy change value is smaller.

  • People make mistakes when doing experiments - the data book values are the values we would get if we always added the correct amount of water etc.

  • Often, experimental values are not calculated under standard conditions.

  • The technique has changed leading to more accurate values, but the data books have not been updated yet.

  • The fuel will sometimes undergo incomplete combustion, meaning that the full amount of energy is not released.

  • Alcohols are very volatile and so some will evaporate from the wick. The value calculated for the number of moles of fuel burnt will be higher than the true value, meaning the value for enthalpy change will be lower than the true value.

Explanation

Question 10 of 15

1

It is important to use a very precise thermometer when calculating the enthalpy change of a reaction.

Select one of the following:

  • True
  • False

Explanation

Question 11 of 15

1

Which of the following are ways in which the calorimetry method can be improved to minimise heat loss? CHOOSE 3

Select one or more of the following:

  • Reduce the distance between the flame and the calorimeter

  • Use a glass rod to stir the water/solution in the calorimeter

  • Put a draught screen around the flame

  • Use a larger spirit burner

  • Put a lid on the beaker/calorimeter

Explanation

Question 12 of 15

1

Experimentally finding the enthalpy change of a reaction, accounting for heat loss
Add a (5.00g) sample of solid to (50g) of and start the stop watch.
Record the of the solution every subsequent minute for approximately 5 minutes.
Plot a graph of temperature (y-axis) versus time (x-axis).
back to the time of (T=0s) to establish the temperature change.
Calculate ΔH in kJ mol-1 using the equation: ΔH = (m × c × ∆T)/(n ×1000 )

Drag and drop to complete the text.

    water
    temperature
    Extrapolate
    mixing
    maximum

Explanation

Question 13 of 15

1

Why is the line of best fit extrapolated back to the time of mixing when calculating enthalpy change?

Select one of the following:

  • To account for the heat lost to the surroundings

  • To eliminate the possibility of anomalous results

  • To find the best temperature at which to carry out the reaction

Explanation

Question 14 of 15

1

Investigate how the rate of reaction changes with temperature
1. Set a to 20ᵒC.
2. Accurately measure out 20cm³ of 1.0 mol dm⁻³ hydrochloric acid and pour into a .
3. Allow the solution of hydrochloric acid to reach the of the water bath.
4. weigh out 1.0g of magnesium ribbon.
5. Place the magnesium into the conical flask, immediately attaching the and starting a timer.
6. Record the of gas evolved in the first 20 seconds.
7. Repeat steps 1 – 6 for a of temperatures (30ᵒC – 60ᵒC).
8. Plot a graph of temperature () versus initial rate (cm³/20s) ().

Drag and drop to complete the text.

    water bath
    conical flask
    temperature
    Accurately
    gas syringe
    volume
    range
    x-axis
    y-axis

Explanation

Question 15 of 15

1

It is not possible to accurately measure the effect of temperature on rate of reaction at temperatures above 60ᵒC.

Select one of the following:

  • True
  • False

Explanation