Yr12 Transition Skills
1: Attention: Use a range of techniques, recording observations to justify a
conclusion.
2:Organisation: Use online resources to support learning and practical skills.
3: Thinking: Develop subject specific skills required for post 16 course.
Intro IB Use
• STEM Center
• IA’s and EE’s
• Equipment
• Working area
• Outside
• Lab
• Lessons
• Other users
Intro Al-level use
• Stem center
• Practical exams
• In class development of skills
• Lessons
• Other users
• Goggles
Lab Session
• Aim: to carryout a range of techniques and record observations in order to deduce the
order in concentrations of Glucose solutions (A-D).
• For each test carry out and record your observations in the sheet.
• At the end of the lab time, analyse your results and determine the correct order of
concentration.
• Do all of your results agree, do some test have a higher precision, when could they/
couldn’t they be used?
i.
ii.
iii.
iv.
v.
Benedicts test
Viscosity- flow rate
Viscosity- terminal velocity
Refraction
Oxidation Reduction Probe
i) Benedicts test
• Glucose can reduce Blue Copper 2+ ions into the red
Copper 1+, as the change occurs the colours reflect Blue
being used up and red being formed.
• Instructions:
• Put a sample approximately 1cm high of each glucose
solution into different test-tubes,
• Add approximately 1cm high of benedicts solution into
each test-tube.
• Add to water bath (80oC, beware of high heat), after
1min and 2min record observations.
• After 2 min pour into waste beaker.
ii) Viscosity- Flow rate
• Glucose forms relatively strong hydrogen bonding (a form of intermolecular attraction)
with water, The greater the amounts of intermolecular forces between molecules with
higher concentrations will make it harder for the molecules to pass past each other and
flow, making the solution more viscous (gloopy).
• Instructions
• In filled burette for each solution open the tap full and record the time taken to drain
from 10.00cm3 to 20.00cm3.
• Repeat for each solution, add the liquid back into the burette with the funnel after
completion.
• Calculate the flow rate volume transferred/time taken to flow in the unit cm3/s
iii) Viscosity- Terminal velocity
• Glucose forms relatively strong Hydrogen bonding (a form of intermolecular attraction)
with Water, The greater the amounts of intermolecular forces between molecules due to
higher concentrations, makes it harder for the molecules to pass past each other, making
the solution more viscous (gloopy). This therefore offers greater resistance to an object
passing through, decreasing the terminal velocity.
• Instructions
• In Burettes set up with each solution, carefull drop a metal ball bearing, record the time
it takes to pass from 40cm3 to 50cm3 (10cm of distance) .
• Repeat for each solution
• Calculate the velocity= distance/time taken.
iv) Refraction of a beam of light
• In the food and brewing industries Glucose level are
often need to be checky often and quickly. One method
for this is to use a refractometer. The greater the
concentration of the solution the greater the density
and therefore the slower velocity that light can travel
through the medium. The bigger the difference in
velocity between air and the solution the greater the
effect of refraction.
• Instructions
• Place the container with the glucose solution on the
line(see diagram), aim ray to have a a 45O angle of
incidence at the center of the laminated protractor,
record the angle of refraction (angle between refracted
ray and normal).
• Repeat for each solution.
Oxidation Reduction Probe
• Glucose has a tendency to be oxidise, an Oxidation Reduction
probe can measure the potential difference of glucose’s potential
to oxidise and waters, the higher the concentration of glucose the
higher the potential difference.
• Instructions
• Start up the Sparkvue app on the ipad (1-3), connect to the ORP
Sensor (labelled pH as it uses the same wirless device as the pH
probe)).
• Click for the sensor data “Digits” (4)and the value in mV will be
displayed (5).
• Insert the sensor into the solution( unscrew the bottom (6), click
on the green start icon and record data value. (7)
• Before putting the probe into the next solution wash carefullywith
the distilled water over the sink.
• Repeat for the other solutions.
• Ensure that you screw the protection lid with the storage solution
back after use.
1
6
2
4
3
5
7
Evidence
• After each section place the solution in order and justify your
decision.
• After all tests carried out, what is your overal decision and
justification.