Standard solutions

Question 1

What is the definition of a standard solution?

Answer 1

Have been prepared by a chemist
Have an accurate known concentration

Question 2

What are the 2 main ways to prepare a standard solution?

Answer 2

Dissolving a solid in distilled water
Diluting a known concentration of an existing solution with distilled water

Question 3

Describe one method on how to prepare a standard solution

Answer 3

Measure a known mass, by difference, using a mass balance.
Dissolve in a small amount of water in a flask/beaker.
Transfer to a 250cm³ volumetric flask (use a funnel).
Rinse the original flask with water.
Transfer washings to the volumetric flask.
Carefully make up to the line with water (bottom of the meniscus on the line) using a dropping pipette.
Stopper.
Invert to mix.

Question 4

Describe the second method on how to prepare a standard solution

Answer 4

Using pipette, transfer the original solution to a new volumetric flask.
Carefully fill the volumetric flask to the line, with more distilled water.
Stopper.
Invert to mix.

Question 5

Do the number of moles change when you dilute the standard solution with water?

Answer 5

No

Question 6

What can some portions of the standard solution prepared be used for?

Answer 6

Titration

Question 7

Will the number of moles of the portion taken out be different to the number of moles in the volumetric flask?

Answer 7

Yes