Question

How would you prepare 100 ml of 0.4 M MgSO4 from a stock solution of 2 M MgSO4?

My attempt at answering this:
Using the formula (Vi)(Mi)=(Vf)(Mf)
(Vi)(2M)=(100)(0.4)=200-100(final volume)=100 ml
I am assuming you would add 100 ml of water to the 2 M MgSO4 200 ml to get the 0.4 M MgSO4 100 ml

Answer 1

OK, so to answer this question, you will simply use the molality equation which is as follows:
M1V1 = M2V2 
In the givens you have:
M1 = 2M
V1 is the unknown
M2 = 0.4M
V2 = 100 ml

plug in the givens in the above equation:
2 x V1 = 0.4 x 100 
therefore:
V1 = 20 ml

Based on this: you should take 20 ml of the 2 M solution and make volume exactly 100 ml in a volumetric flask by diluting in water.

Answer 2

To prepare 0.4M, 100 ml of solution, 20 ml of the 2 M stock has to be taken, and the volume has been makeup to 100 ml with the solvent.

To prepare the diluted solution from the stock solution, the amount of stock solution required will be calculated as:

M1V1 = M2V2

Where M1 and V1 are the molarity and the volume of stock

M2 and V2 are the molarity and volume of solution to be prepared.

100 ml $\times$ 0.4 M = Volume of stock $\times$ 2 M

Volume of stock = 20 ml

Thus to prepare 0.4M 100 ml of solution, 20 ml of the 2 M stock has to be taken, and the volume has been makeup to 100 ml with the solvent.

For more information about molarity, refer to the link:

https://brainly.com/question/25256765