1. Preparing Standard Solutions
From Solids
From Liquids

2. What is a standard solution?
A standard solution is a solution whose concentration is known accurately.
Its concentration is usually given in mol/L.
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 used to make up the solution.

3. Standard solution from Solid
Take a watch glass and place it on the balance. Tare the balance (set it to zero). Carefully weigh out the required mass of substance.
2. Transfer this amount to the appropriate sized volumetric flask. Be careful to transfer all of the solid

4. 3. Add enough distilled water to half-fill the volumetric flask
3. Add enough distilled water to half-fill the volumetric flask. Swirl to dissolve the crystals.
4. Add distilled water to just below the line on the volumetric flask.
Add the final drops carefully to ensure that the bottom of the meniscus is on the line.
5. Put the lid on the flask and turn the flask over a couple of times to mix the solution.
6. Label your solution with your name, the date, and the contents, e.g. 2.0M NaCl. Then tidy up!

5. Standard Solution from Liquid
This can also be referred to as a dilution.
A small volume of a solution of known
concentration is used to make a
diluted solution.
The new concentration can be calculated
using the equation below.
            c1v1=c2v2         
First, an exact volume of a solution of known concentration is pipetted into a clean volumetric flask.
Second, the solution is diluted to the volumetric
mark using distilled water.

6. Concentration Units % by mass - medicated creams
% by volume - rubbing alcohol
ppm, ppb - water contaminants
molarity - used by chemists
molality - used by chemists

7. PPM, PPB
Parts per million is a unit used for VERY LOW concentrations of solute

8. Example
Find the concentration of a 3.5 mL sample if 3.0 x 10-6 g of a toxin is found in the sample.

9. Calculating Solute needed for Standard Solutions
Calculate the mass of Zn(NO3)2 needed to make up mL of 1.5 M solution

10. Calculating Dilution
What volume of 18M H2SO4 is needed to prepare mL of 2.5M H2SO4?