metric system

2. • Metric system – universal system of measurement used by all scientists
worldwide
• International system of units – also known as the SI system
• A version of the metric system used by scientists
• Metric units commonly used in biology:
• Meter (m) – basic unit of length
• Liter (L) – basic unit of volume
• Kilogram (kg) – basic unit of mass
• Degrees Celsius (C) – basic unit of temperature
• Seconds (s) – basic unit of time

4. • Used to measure very small volumes of liquid
• Measure volume of liquid in microliter (μl)

6. Maximum
volume
p10 can
hold is
10μl
Maximum
volume
p20 can
hold is
20μl
Maximum
volume p100
can hold is
100μl
Maximum
volume p200
can hold is
200μl
Maximum
volume
p1000 can
hold is 1000μl

8. How to draw liquid into the
micropipette:
1. Use appropriate tip for the micropipette you
are using
2. Press down on the plunger up to the
resistance. DO NOT GO PAST THE
REISTSANCE.
3. Insert tip into the fluid you want to withdraw.
4. Slowly lift your finger from the plunger, while
keeping the tip submerged in the liquid.
5. Remove micropipette from the liquid
It is important to follow these steps carefully to
prevent any air bubbles from forming and therefore
giving you faulty results
How to dispense liquid into new
container:
1. Place tip of micropipette into a new container.
Make sure the tip is touching the bottom or at
least the inside of the container.
2. Press down on the plunger, but this time go
past the resistance to ensure that you have
dispensed all the liquid in the tip
3. Press on the Tip Ejector button to eject the tip
into the appropriate waste container
It is important to follow these steps to prevent major
error and faulty results

9. Lab
Procedures
for Practice II

10. • six test tubes
• 3 colored solutions:
• Red
• Blue
• Yellow
• Water
• Micropipette p1000
• Tips

11. • Setting up the 6 test tubes:
1. Label (1, 2, 3, 4, 5, and 6) the six tubes
at your station,
2. Put 2100 μL of red water solution into
test tube number I
3. Put 2300 μL of yellow water solution into
test tube number 3
4. Put 2500 μL of blue water solution into
test tube number 5

12. • Constructing color spectrum: Be sure to record your actions in Table II:
1. Take 500 μL from test tube number 1 and add it into test tube number 2.
2. Take 500 μL from test tube number 1 and add it into test tube number 6.
3. Take 500 μL from test tube number 3 and add it into test tube number 4
4. Take 500 μL from test tube number 3 and add it into test tube number 2
5. Take 500 μL from test tube number 5 and add it into test tube number 4
6. Take 500 μL from test tube number 5 and add it into test tube number 6
• Crunching the numbers
1. Calculate the total final volume of liquid in each tube.
2. Convert volume from μL to ml
3. Write color appeared in final solution

14. Lab Procedure
for Practice III

15. • six 1.5ml tubes
• 3 colored solutions:
• Red
• Blue
• Yellow
• Water
• Micropipette p100 & p10
• Tips

16. • Setting up the tubes:
1. Label (1, 2, 3, 4, 5, and 6) the six 1.5ml
size tubes at your station,
2. Put 25 μL of red water solution into test
tube number I
3. Put 30 μL of yellow water solution into
test tube number 3
4. Put 40 μL of blue water solution into
test tube number 5

17. • Constructing color spectrum: Be sure to record your actions in Table III:
1. Take 5 μL from test tube number 1 and add it into test tube number 2.
2. Take 5 μL from test tube number 1 and add it into test tube number 6.
3. Take 5 μL from test tube number 3 and add it into test tube number 4
4. Take 7 μL from test tube number 3 and add it into test tube number 2
5. Take 7 μL from test tube number 5 and add it into test tube number 4
6. Take 7 μL from test tube number 5 and add it into test tube number 6
• Crunching the numbers
1. Calculate the total final volume of liquid in each tube.
2. Convert volume from μL to ml
3. Write color appeared in final solution

20. • Solution = solute + solvent
• Solvent: substance in which the solute is dissolved in
• It is usually a liquid
• Water is the solvent, unless otherwise stated
• Solute:
• Substance that is dissolved in the solvent

21. • Percent of weight of solute in total weight of the solution
• Percent solution (%W/W) = Mass of solute (g) x 100
Mass of solution (g)
• Example: to make 100% (W/W) NaCl solution, you would weigh 100g of NaCl and dissolve it in
100g of solution
• Percent of weight of solution in the total volume of solution
• Percent solution (%W/V) = Mass of solute (g) x 100
Volume of solution (ml)
• Example: 4% (W/V) NaCl solution is 4g of NaCl in 100mL of solution

22. • Percent of volume of solute in the total volume of solution
• Percent solution (%V/V) = Volume of solute (ml) x 100
Volume of solution (ml)
• A 10% (V/V) ethanol solution is 10mL of ethanol in 100mL of solution

23. • Molar solution (M)
• M = Moles of solute = mol
Liters of solution L
• It is a solution that contains 1 mole of solute per liter of solution
• Mole is the number of gram molecular weight (gMW)
• For this reason, we can also say that:
• 1M = 1gMW solute
Liter of solution

24. • V1C1 = V2C2
• V = volume
• C = Concentration (%,M,N)
• V1 = volume of starting solution C1 = concentration of starting solution
• V2 = final volume of new solution C2 = final concentration of new solution
• Example: How much 12N HCl is needed to make 400ml of 2N solution?
• Use the formula: V1C1 = V2C2
V1 (12N) = (400ml) (2N)
V1 = 66.7ml