Unit 4 - P4, M3, D3 - Searching and Using of Instruments and Sensors to Test Materials

Unit 4 – P4, M3, D3

The use of Instruments and Sensors to Test Materials

Procedures
Microscopy – cheek cell
Equipment:
 Microscope slide  Cover slide  Sterile cotton swab  Saline
 Methylene blue  Tissue  Graticule  Macro meter
 Microscope  Pipette

Method:
1. Using a sterile cotton swab, swab the inside of the cheek ensuring it’s efficiently coated
2. Add one drop of saline to a microscope slide
3. Spread the saline around the microscope slide with the coated cotton swab to
transfer a layer of cheek cells
4. Add one drop of methylene blue which allows the cells to become visible under
a microscope
5. At a 45 degree angle, place a cover slip on top of the methylene blue which
prevents the formation of air bubbles
6. With tissue, dab off any methylene blue that seeped out the sides
7. Working up from the red, yellow and blue lenses, focus on a single cheek cell
8. Insert a graticule into one of the eye pieces
9. Using the blue lens focus the single cell with the graticule also in view
10. Change the microscope slide with a macro meter slide
11. Focus the macro meter and graticule on the blue side so its visible
to see how many increments of the graticule are in a macro meter




pH – household items
Equipment:
 Household items  Beakers  Pipettes  pH probe
 Universal indicator  Universal indicator  Litmus paper red  Litmus paper blue
paper solution
 Tweezers  Pipette


Methods:
Gather all household items being used




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1.

, 2. Using a clean pipette for each item, add 2ml into clean separate beakers
3. For universal indicator solution, carry this out last as it completely changes the colour of each
item

UIS:
1. In each beaker, add 2-3 drops of universal indicator solution
2. Record down the colour change and reference this with a pH colour chart to
find the approximate pH number
3. Write down the pH number for each item

UIP:
1. Holding the universal indicator paper at the bare end, dip each paper
into each item
2. Using the box where the papers were taken from, use the guide to
match the colours on the paper to the colours on the box
3. Write down the pH number for each item

pH probe:
1. Calibrate the pH probe using a larger beaker of buffer 7
2. Dip the pH probe into each item
3. Make sure to wash the pH probe using buffer 7 after each item to minimise
cross contamination
4. Write down the pH number for each item

Litmus paper red:
1. Dip the tweezers into buffer 7 to clean them from any contaminants
2. Using the tweezers dip litmus paper red into each item and watch for any
changes to show acid
3. Make sure to wash the tweezers using buffer 7 after each item to minimise
cross contamination
4. Write down positive if a change occurred and negative if no change occurred

Litmus paper blue:
1. Dip the tweezers into buffer 7 to clean them from any contaminants
2. Using the tweezers dip litmus paper blue into each item and watch for any changes to show
alkaline
3. Make sure to wash the tweezers using buffer 7 after each item to minimise cross contamination
4. Write down positive if a change occurred and negative if no change occurred

Time – disappearing heart
Equipment:
 0.1M sodium  1M hydrochloric acid  Conical flask  Paper
thiosulphate
 10ml measuring  50ml measuring cylinder Stopwatch  Black marker
cylinder
 Thermometer

Method:
1. Collect all pieces of equipment
2. Draw a shape (heart) on the white piece of paper with a black marker
3. Measure out 50ml of sodium thiosulphate and pour into a conical flask