DILUTING A SOLUTION LAB
Purpose
Prepare a 100.00 mL solution of 0.016 mol/L from a 0.20 mol/L stock
solution of potassium nitrate.
Chemicals & Equipment
1. 100.00 mL of 0.20 mol/L potassium nitrate
solution
3. 150 mL beaker
5. Distilled water
7. 10 mL graduated cylinder
2. Dropper
pipet
4. 50 mL beaker
6. Funnel
Procedure
1. Obtain all chemicals and equipment.
2. Empty all of 0.20 mol/L stock solution into a 150 mL beaker.
3. Rinse the volumetric flask 3 times with very small amounts of
distilled water. Fill 1/3 full with distilled water and set aside.
4. Fill a 10.0 mL graduated cylinder with the correct amount of stock
solution. Use a dropper pipet to obtain a precise amount.
5. Check your work with the instructor before moving on to the next
step.
6. Pour the solution from the graduated cylinder into the volumetric
flask.
7. Fill to just under the calibration mark.
8. Put a very small amount of distilled water into a 50 mL beaker and
use the dropper pipet to fill the volumetric flask to the calibration
mark.
9. Stopper your solution and check with your instructor.
10.Invert the solution 3 times to mix.
11. Rinse all remaining solutions down the drain with lots of running
water, rinse remaining and put everything away.
DILUTING A SOLUTION LAB
Before you begin to obtain glassware and chemicals, EACH
member of the group must check in with Mr. Deakin 3 times
during this experiment.
1. Show me your complete answer, including your statement
– to the prompt:
Explain how to make a 100.00 mL solution of 0.016 mol/L
potassium nitrate from a 0.20 mol/L stock solution.
check your answer here.
2. Show me a volumetric flask 1/3 full of water and a
graduated cylinder filled with the appropriate mL of 0.20
mol/L stock solution.
3. Show me how you lined the meniscus up with the
graduation mark on the neck of the volumetric flask
BEFORE you invert and mix your solution.
DILUTING A SOLUTION LAB RUBRIC
Criteria
Novice
Intermediate
Student is nagged once
or more about not
following proper safety
precautions
Expert
Student observes
proper safety
precautions
Student does not wear
their safety goggles or
has a lab accident
Student follows
written and
verbal
instructions
Evidence that the
student has not
followed more than one
written or verbal
instruction
Evidence that the
student has not
followed one written or
verbal instruction
Student follows all
written or verbal
instructions
Evidence of
equitable
participation
Little or no evidence of
equitable participation
by a group member
Some evidence that a
group member
participated more than
another
Evidence that all
group members
participated equitably
Lab station is
cleaned up after
lab
More than one piece of
evidence remains of
chemicals or equipment
after cleanup
Evidence of chemicals
or a piece of equipment
remains after cleanup
Entire station is
cleaned up with no
evidence remaining of
equipment or
chemicals
All aspects of the lab
are conducted in a safe
manner