How to make standard solutions in high school chemistry lab

1. Making Standard Solutions
What is a standard solution?
A standard solution is a solution whose concentration is known
accurately. Its concentration is usually given in mol dm–3.
When making up a standard solution it is important that the correct mass
of substance is accurately measured. It is also important that all of this is
successfully transferred to the volumetric flask (picture) used to make up
the solution. The following procedure will make sure that this happens.
Background calculations
1. Determine the number of moles needed to make up a solution with the
required volume and concentration.
2. Determine the molar mass Mr, of the chosen substance.
3. Work out the mass of substance needed using your answers from steps 1 and 2.
Making up the solution
1. Take a weigh boat and place it on the balance.
2. Tare the balance (set it to zero).
3. Carefully weigh out the required mass of substance.
4. Transfer this amount to a beaker. Add water from a wash bottle to dissolve it.
5. Use some of the water to rinse all the substance off the weigh boat. Do this at least twice.
6. Stir with a glass rod until all the solid is dissolved, then transfer the solution to the
volumetric flask.
7. Use more water from the wash bottle to rinse out the beaker and the glass rod. Do this at
least twice.
8. Add water to just below the line on the volumetric flask.
9. Add the final drops with a plastic dropper pipette to ensure that the bottom of the
meniscus is on the line.
10. Put the lid on the flask and turn the flask over a couple of times to mix the solution.
11. Label your solution with your name, the date, and the contents, e.g. 2.0 +/- ___ M NaCl.

2. Uncertainty of a volumetric flask
Equipment
/Glassware
Picture Size & Uncertainty
(read the actual
device)
Notes
Volumetric flask 100.00 ± 0.08 mL
250.0 ± 0.1 mL
500.0 ± 0.2 mL
1000.0 ± 0.3 mL
*see the full chart
below this table.
● Most common
for making
solutions.
● TC means
calibrated “to
contain”
*American Society For Testing and Materials (ASTM) at 20 ℃