applied science unit 3 practicals

Enzymes - concentration practical Hypo

If the concentration of hydrogen peroxide is increased, then the filter paper disk will rise quicker.

This is because there will be more substrate particles so there will be more frequent successful collisions when the substrate binds to the active site of the enzyme. This causes the rate of reaction to increase, so oxygen will be produced faster, causing the disk to rise faster.

Variables- enzymes conc

Independent - concentration of hydrogen peroxide

Dependent - time taken for the filter paper disk to rise

Control - volume of hydrogen peroxide, volume of celery extract, temperature of solutions, pH of solutions, type and size of filter paper disc

equipment-enzymes conc

• 25 cm3 measuring cylinder - to measure the volume of solutions

• pH probe - to measure the pH of the solutions

• Thermometer - to measure the temperature (so solutions are at the same temperature)

• Hydrogen peroxide of different concentration (1, 2, 3, 4, and 5 vol) - this is the substrate in the reaction

• Celery extract - this is the enzyme in the reaction

• Stop clock - to measure the time taken for the paper disk to float

• Boiling tube - where the reaction will take place

Stirring rod - to transfer the disk from the celery to the hydrogen peroxide

• Filter paper disks (same type and size) - to absorb the celery extract

method- enzymes conc

1. Use a 25 cm3 measuring cylinder to add 25 cm3 of 1 vol hydrogen peroxide into a boiling tube

2. Use the pH probe to check the pH, and the thermometer to check the temperature of the hydrogen peroxide

3. Place a filter paper disk into celery extract for 5 minutes

4. Use a glass rod to transfer the filter paper disk into the boiling tube. Make sure it goes to the bottom

5. Start the stop clock and measure the time take for the filter paper disk to rise to the top

6. Repeat steps 1-5 using the same concentration of hydrogen peroxide, then calculate a mean average

7. Repeat steps 1-6 using different concentrations of hydrogen peroxide (2, 3, 4, and 5

8. Draw a results table...

9. Plot a graph of the results...

enzymes PH practical Hypo

The optimum pH of amylase for the breakdown of starch is pH 7.

If the pH is too high or too low then the charge of the amino acid will change, which changes the tertiary structure of the enzyme, which changes the shape of the active site. If the enzyme denatures, then the rate of reaction will slow down.

variables enzymes PH

Independent - pH of the buffer solution

Dependent - time taken for the iodine solution to stay orange

Control - volume of solutions, temperature of solutions, concentration of solutions, time intervals between adding the solution to the iodine

equipment enzymes PH

• Amylase solution - this is the enzyme that catalyses the reaction

Starch solution - this is the substrate of the reaction

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pH buffer solutions - to change the pH

Water bath and thermometer - to ensure that the temperatures are constant

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lodine solution - to detect if starch is present

Pipette - to add the solutions

Test tubes - to hold the solutions Stop clock - to time the reaction

Spotting tile - to see the colour changes

method enzymes PH

1. Use a pipette to add 1 cm3 of amylase solution, pH 4 buffer solution, and starch solution into separate test tubes, and place each in water bath at 35 °C for

5 minutes

2. Use a pipette to place a drop of iodine solution into each well of a spotting tile

3. Mix the amylase solution, pH 4 buffer solution, starch solution

4. Use a pipette to add drop of the mixture into 1 well of iodine and start the stop clock

5. At 30 second intervals, add 1 drop of the mixture into another well there is no longer a colour change

6. Repeat steps 1-5 2 more times and calculate a mean average

7. Repeat steps 1-6 using different pH buffer solutions (5, 6, 7, 8, 9, 10)

8. Draw a results table...

9. Plot a graph of the results...

Diffusion Hypo

f the surface area:volume is increased, the rate of diffusion increases.

This is because as surface area increases the area of which molecules can spread increases, causing the rate of diffusion to increase.

Variables -diffusion

Independent - surface area:volume of agar gel

Dependent - time taken for the agar gel to turn completely colourless

Control - temperature of HCI, volume of HCI, concentration of HCI, time left soaking in phenolphthalein, same person looking at the colour of the cube

equipment diffusikn

Agar gel cubes (made with sodium carbonate) - substance that hydrochloric acid will diffuse into

• 1M hydrochloric acid - this will change the pH of the agar gel

Phenolphthalein - this will turn from pink to colourless when the acid is added

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15cm ruler - to measure the surface area:volume of the cube

• Stop clock - to measure the time taken for the cube to turn colourless

Tweezers - to move the cubes

Scalpel - to cut the agar gel into cubes

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250ml beaker - to hold the cubes and acid

Thermometer - to measure the temperature of the acid

method diffusion

1. Soak the agar gel cubes in phenolphthalein for 10 minutes (use a stop clock to time)

2. Use a 15 cm ruler (with mm measurements) and a scalpel to cut the agar gel cubes of different sizes (10mmx10mmx10mm, 5mmx10mmx10mm, 5mmx5mmx10mm, 5mmx5mmx5mm, 2.5mmx5mmx5mm)

3. Use tweezers to place each cube at the bottom of a 250 ml beaker, make sure they are spaced out

4. Use a thermometer to measure the temperature of 1M HCl, then gently pour until all of the cubes are completely covered and start the stop clock

5. Time how long it takes for each cube to go from pink to completely colourless

6. Repeat steps 1-5 2 more times and calculate the mean average time taken

7. Record the results in a results table...

8. Plot a graph...

photon temp hypo

As the temperature increases, the rate of photosynthesis decreases.

As temperature increases the particles will have more energy so they will move faster and there will be more frequent successful collisions. This will lead to more oxygen gas bubbles being produced.

equipment photo temp

• Pondweed - this will photosynthesise

• 1% sodium bicarbonate solution - provides water and carbon dioxide for photosynthesis

• Scissors - to cut stem of pondweed

• Water bath - to set the temperature

• Stop clock - to time 1 minute

• Lamp - to provide light for photosynthesis

• Ruler - to measure distance from lamp

• 25 cm 3 measuring cylinder - to measure volume of sodium bicarbonate solution

method photo temp

1. Use a 25 cm 3 measuring cylinder to add 25 cm of 1% sodium bicarbonate solution into a boiling tube. Place into a water bath set at 10 °C

for 10 minutes

2. Use scissors to cut the end of the stem of a piece of pondweed, and place into the boiling tube so that the stem is facing upwards. Gently push down to the bottom of the boiling tube

3. Use a 30 cm ruler to place the lamp 5 cm away from the boiling tube

4. Turn the lamp on and ensure that it is the only light source in the room

5. Start the timer and count the number of bubbles produced in 1 minute

6. Repeat this twice more and calculate a mean average

7. Repeat but place the pondweed into the water bath at different temperatures (15, 20, 25, 30 °C)

8. Record the results into a table...

9. Plot a graph of...

variables photo temp

Independent - temperature (of the solution)

Dependent - number of bubbles produced in 1 minute

Control - light intensity (distance from light source), carbon dioxide concentration, volume of sodium bicarbonate solution, temperature of solutions

alcohol hypo

If the chain length of the alcohol increases, then the heat of combustion/energy released increases

This is because as chain length increases there are more atoms, so more bonds are formed to make the products which is an exothermic process.

variables alcohol

Independent - chain length of the alcohol

Dependent - mass of fuel used to increase the temperature by 30°C / heat of combustion

• Control - starting and final temperature, mass/volume of water used, height of the water above the flame, insulation

equipment alcohol

Copper calorimeter - to hold the water

50 cm measuring cylinder - to measure the volume of water

Clamp and clamp stand - to hold the conical flask and thermometer

Mass balance - to measure the mass of the spirit burner

Thermometer - to measure the temperature change of the water

Spirit burner - to hold the alcohol

30 cm ruler - to measure the height of the water above the flame

• Alcohols of different chain lengths (1,2,3,4,5 carbons) - the fuel of the combustion reaction

method alcohol

1. Place the alcohol with 1 carbon in the chain into the spirit burner and record the starting mass using the mass balance

2. Use the 50 cm3 measuring cylinder to measure 50 cm3 (50g) of water and pour into a copper calorimeter

3. Attach to the clamp stand and use the 30 cm ruler to make sure the calorimeter is 10 cm above the spirit burner

4. Use the thermometer to measure the starting temperature of the water

5. Light the spirit burner. Extinguish when the temperature has increased by 20

°C

6. Measure the final mass of the spirit burner

7. Repeat steps 1-6 twice and calculate a mean average change in mass, heat energy supplied to water, and heat of combustion

8. Repeat steps 1-7 with alcohols with a different chain length (2,3,4,5)

9. Record results in a table...

10. Plot a graph of...

thermistor hypo

As the temperature increases, the resistance of the thermistor decreases.

This is because increasing the temperature allows more electrons to flow and carry the current, which decreases the resistance.

variables thermistor

Independent - temperature of the water

Dependent - resistance of the thermistor

Control - volume of water, type of thermistor, length of wires

equipment thermistor

Hot plate - to change the temperature of the water

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Thermometer - to measure the temperature of the water

Thermistor - the resistance of this will change

Multimeter - to measure the resistance of the thermistor Wires - to connect the thermistor and the multimeter

250 cm3 beaker - to hold the water

• 100 cm3 measuring cylinder - to measure 100 cm3 of water

method thermistor

1. Use the 100 cm 3 measuring cylinder to add 100 cm3 of water into a 250 cm3 beaker

2. Place the beaker onto the hot plate

3. Connect the thermistor to the multimeter using the wires, and place the thermistor into the water so that it is completely submerged

4. Place the thermometer into the water as close to the thermistor as possible, and turn on the hot plate until the temperature of the water near the thermistor is 20 °C (make sure to stir the water)

5. Record the resistance of the thermistor

6. Repeat at that temperature twice more and calculate the mean average resistance

7. Repeat for different temperatures (30, 40, 50, 60 °C)

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Record the results in a table...

9. Plot a graph of...