## Molarity formula

Kalsuda Lapborisuth 1B
Posts: 27
Joined: Fri Apr 06, 2018 11:03 am

### Molarity formula

I understand the material so far but I wonder if there are situations/problems where the formula MiVi = MfVf cannot be used?

LilianKhosravi_1H
Posts: 32
Joined: Fri Apr 06, 2018 11:03 am

### Re: Molarity formula

I think as long as you are given three of those things from the formula then you can use it. You might even be given the mole rather than M or V which you can substitute in place of MiVi since n(moles)=MV

Paywand Baghal
Posts: 32
Joined: Fri Apr 06, 2018 11:01 am

### Re: Molarity formula

Say you're given two known variables and one unknown, for example you need to find the number of atoms and you have the Molarity and volume, you would use n=M/v. So that would be an example of where you can't use MiVi=MfVf

Andre-1H
Posts: 39
Joined: Fri Apr 06, 2018 11:01 am

### Re: Molarity formula

That equation basically comes from the fact that in a dilution the amount of moles does not change. It's just a rewritten form of C(molarity)= moles/vol. There could be other questions asking to reorganize the formula to find a different unknown. But for most dilution problems the formula you gave is the go to.

Yixiao Hu 3C
Posts: 45
Joined: Fri Sep 28, 2018 12:19 am

### Re: Molarity formula

I think you can use if whenever you have all the numbers. mv=mv is available all the time without any contidions:)

Dana Wilks 3I
Posts: 30
Joined: Fri Sep 28, 2018 12:23 am

### Re: Molarity formula

I also had a question regarding the molarity formula. Is there a difference between the MiVi=MfVf formula and the Molarity= moles/volume formula? Isn't the first just derived from the latter?

705192887
Posts: 77
Joined: Fri Sep 28, 2018 12:18 am

### Re: Molarity formula

Yes, the first is essentially derived from the latter. Sometimes you will need to use just the M1V1=M2V2, depending on what is given, but sometimes you will need both to complete the problem.