#3 - Making a 1M Hydrochloric Acid bench solution
Hydrochloric Acid (HCl) is supplied in different strengths which makes the calculations difficult when performing experiments, so it’s sensible to have a pre-made solution of a know strength (Molarity) available.
We will assume our stock HCl solution is 36%, and that we wish to make 100ml of 1M solution.
(Typically HCL is in the range 35% to 37%, but you can simply adjust the calucaltions below).
The formula weight of HCl is 36.46 g/mole (for 1 Mole)
So, for 100ml of solution, we need 0.1M of HCl
36.46 / 10 = (weight for 0.1M) = 3.646
3.646 / 0.36 (HCl percentage) = 10.1278g ( 10.13g ) of HCl
Now we know the masses required, we can make the solution.
Instructions:
Fill a 100ml volumetric flask, approximately 1/3 full of distilled water.
Place a 10ml graduated cylinder on some weigh scales and tare to zero.
Slowly fill the graduated cylinder with our stock 36% HCl until the scales show 10.13g (This is around 8.8ml of HCl).
** Slowly ** add the HCl from the graduated cylinder to the volumetric flask that you previously 1/3 filled with distilled water.
Top-off the volumetric flask to the 100ml mark with distilled water.
Put in the stopper and make sure the contents are completely mixed.
Transfer the contents of the volumetric flask to the final labelled glass container.
You can of course apply this technique for making any bench acid solution by substituting the formula weight of the desired acid.
We will assume our stock HCl solution is 36%, and that we wish to make 100ml of 1M solution.
(Typically HCL is in the range 35% to 37%, but you can simply adjust the calucaltions below).
The formula weight of HCl is 36.46 g/mole (for 1 Mole)
So, for 100ml of solution, we need 0.1M of HCl
36.46 / 10 = (weight for 0.1M) = 3.646
3.646 / 0.36 (HCl percentage) = 10.1278g ( 10.13g ) of HCl
Now we know the masses required, we can make the solution.
Instructions:
Fill a 100ml volumetric flask, approximately 1/3 full of distilled water.
Place a 10ml graduated cylinder on some weigh scales and tare to zero.
Slowly fill the graduated cylinder with our stock 36% HCl until the scales show 10.13g (This is around 8.8ml of HCl).
** Slowly ** add the HCl from the graduated cylinder to the volumetric flask that you previously 1/3 filled with distilled water.
Top-off the volumetric flask to the 100ml mark with distilled water.
Put in the stopper and make sure the contents are completely mixed.
Transfer the contents of the volumetric flask to the final labelled glass container.
You can of course apply this technique for making any bench acid solution by substituting the formula weight of the desired acid.