# How Can I Prepare 3 Molar KCL Solution For Volume Of 500 Ml?

The molar mass of KCl is 74.5 (39+35.5).
This means that a 1molar solution would contain 74.5g KCl per liter.
Therefore, a 3 molar solution would contain 74.5 x 3 = 223.5g KCl per liter.
Now, 1 liter has 1000 ml in it. We need to prepare a 3M solution in 500 ml.
Just simple math here. If 1000ml has 223.5g of KCl in it to make a 3M solution, 500ml will have half the amount (since 500 is the half of 1000).
So, we'll divide 223.5 by 2. This gives us 111.75.
So, first of all you need to weigh out 111.75g of KCl. You do this by first weighing the empty dish on the scale and calibrating the scale to zero with the dish on it. Then add KCl to the dish on the scale until the scale reads 111.75g.
Then, you transfer this amount into a round bottomed flask of volume 500ml. After adding KCl, fill up half the bottle and swirl gently to dissolve the solid. Then, make the volume up till the mark to make up 500ml of solution. Cork the bottle and shake it to mix.

thanked the writer.
Anonymous commented
Very helpful. Thank you. Keith Maclean
Anonymous commented
Great .thank you - Carlos Pancham
I have an application note from Denver Instruments to make this solution:

Making 3M KCl Electrode Fill Solution

A 3M KCl filling solution can be easily prepared using Potassium Chloride in the crystalline
form and deionized water. Please follow the steps carefully so you do not change the reference potential of your electrode.
1) Dry the Potassium Chloride carefully in an oven for 2-3 hours
2) Using an analytical balance, carefully weigh 22.368 grams of KCl.
3) Transfer the KCl to a 100 ml class A volumetric flask.
4) Fill the flask to the fill line and mix thoroughly.
5) Verify the volume of the solution after KCl is completely dissolved.
6) Transfer to original filling bottle for use in electrode.

1401 17th Street, Suite 750
Denver, CO 80202
800.321.1135
303.431.7255
303.423.4831 FAX
www.denverinstrumentusa.com
thanked the writer.
gigi samuel commented
What is the oven temperature to dry potassium chloride?