How does temperature affect the rate of reaction?
Equipment
100 cm3 conical flask
Stopwatch
100 cm3 measuring cylinder
10 cm3 measuring cylinder
Teat pipette
Thermometer
Water bath
Sheet of white paper
2 moles per dm3 hydrochloric acid
0.2 moles per dm3 solution of sodium thiosulfate
Method
1 Measure 40cm3 of water into a conical flask.
2 Add 10cm3 of sodium thiosulfate to the conical flask.
3 Warm the solution to 30°C in a water bath.
4 Remove from heat and put the flask on a piece of paper with a cross drawn on
the paper.
5 Add 5cm3 of hydrochloric acid to the flask, swirl the mixture, and start the
stopwatch.
6 Look through the solution from above and stop the stopwatch when you can
no longer see the cross. Record the time.
7. repeat 3 times to obtain an average.
8 Repeat at intervals of 10°C up to 50°C
This method could be used to investigate the following hypothesis:
‘The strength of a polymer strip depends on the width of the polymer
strip.’
Equipment
Plastic carrier bag
Scissors
sellotape
100 g masses with hanger
Hole punch
Drawing pins
Scrap paper
Ruler
Soft wood block
1 cm x 1 cm x 7 cm
Clamp stand
Method
1 Cut a strip of polymer from a plastic bag 2 cm wide and 25 cm long.
2 Fold over at one end of the strip and stick it down on both sides with sellotape
tape. This is the bottom.
3 Place the taped double layer of polymer strip between two pieces of paper.
Use the hole punch to make a hole in the centre of the taped area as shown.
4 Tape the top of the strip to one side of the wood block. Wrap the polymer strip
round the block tightly. Fix the strip in place using two drawing pins on the
back of the wooden block.
5 4 cm from the top make a cut about 2 mm.
7 Place the mass hanger through the hole and add masses until the cut starts to
tear. Record the total mass if the strip breaks, record this as your final mass.
8 Repeat at intervals of 2cm.
Centre of mass
Equipment
Lego
Plank. This should have a thin strip of wood glued across it to stop the tower
from sliding down the plank.
Protractor
Ruler
Method
1 Build a solid, square section tower using the lego blocks and measure the
height.
2 Measure the distance from the base of the tower to the point halfway up. This
is the centre of mass.
3 Place the tower on the plank against the thin strip of wood.
4 Tilt the plank until the tower falls over.
5 Measure and record the angle at which the tower falls.
6 Repeat, adding one row of lego blocks each time, making sure to measure the
exact height.
Biogas
Equipment Yeast
100 cm3 conical flask with bung and delivery tube
Water bath
Thermometer
Balance
Measuring cylinder (10cm3 or 100cm3)
Clamp stand
Vegetable oil
Pipette
Balance
Stop clock
Method
1 place 25cm3 glucose solution into the conical flask, place in the water bath at
30°C.
2 Add 2g of dry yeast. Swirl the flask to mix the yeast and the solution.
3 Top up the flask to 75cm3 using glucose solution.
4 Add a thin layer of oil onto the surface.
5 Add the bung and delivery tube.
6 Turn a measuring cylinder full of water upside-down into a beaker half-full of
water.
7 Put the delivery tube under the measuring cylinder. (See diagram).
8 Measure and record the volume of gas released.
9 Repeat steps 1 to 8 at intervals of 10°C up to 60°C.
Further Additional Science / Physics – PU3.4a Centripetal Force
Equipment
15 cm plastic tube
Rubber bung attached to string
Set of slotted masses
Metre rule
Paper clip
Stop watch
Method
1
Pass the string through the tube and attach the slotted masses to the
end.
2
Set the length of the string between the top of the tubing and the centre
of the rubber bung to 80 cm.
3
Fix a paper clip on the string 1 cm below the bottom end of the tube.
4
Hold the tube in your hand and swing the rubber bung in a horizontal
circle above your head. Adjust the speed so that the paper clip stays 1
cm below the end of the tube.
5
When you have practised this, get someone to time 10 complete
rotations of the bung.
6
Record the time taken for 10 rotations and the value of the centripetal
force. 7 Repeat the experiment, adding 1 slotted mass at a time
Risks
The bung might hit someone, stand well away from the practical
The masses could fall, be careful of your feet
Bouncing Balls ISA
This method could be used to investigate the following hypothesis:
‘How high a ball bounces depends on the temperature of the ball.’
Equipment
250 ml beaker
Heating equipment (e.g. Bunsen burner, tripod, gauze, heat-proof mat)
Thermometer
Tongs
Ball
Metre rule or tape measure
Method
1 Place the ball in a beaker of water and heat to 30°C.
2 Using tongs remove the ball and hold the ball at a height of 50cm above a
hard surface.
3 Release the ball and measure and record the height to which the ball bounces.
5 Repeat steps 1 to 4 for temperatures of 40°C 50°C and 60°C.