Units for Dilution Equation [ENDORSED]
Moderators: Chem_Mod, Chem_Admin

 Posts: 102
 Joined: Wed Sep 30, 2020 9:33 pm
 Been upvoted: 4 times
Units for Dilution Equation
When using the dilution Equation M1V1=M2V2, do my units for volume have to be in liters, or can I sometimes use milliliters if I'm going to keep units consistent? I often see problems where we are being asked to put our answers in mL, and I was just wondering if we could keep the units.

 Posts: 94
 Joined: Wed Sep 30, 2020 9:36 pm
 Been upvoted: 2 times
Re: Units for Dilution Equation
I believe they have to be liters because molarity is mol/L and the units have to match. If it asks you to put your answer in mL, I would just convert my final answer in L to mL.

 Posts: 88
 Joined: Wed Sep 30, 2020 9:38 pm
Re: Units for Dilution Equation [ENDORSED]
For volume, as long as the units remain constant in the initial and final, you can use either mL or L. It does not matter as long as the question does not specify. However, if you are looking for molarity, you will have to convert to L since M = mol/liter.
Last edited by Mina Tadros 3L on Mon Oct 05, 2020 12:02 pm, edited 1 time in total.

 Posts: 49
 Joined: Wed Sep 30, 2020 9:31 pm
Re: Units for Dilution Equation
I would give my final answer in liters since it is the most common unit even if the data given is milliliters always convert it at the end unless they specifically specify to give the answer in milliliters.

 Posts: 130
 Joined: Wed Sep 30, 2020 10:03 pm
Re: Units for Dilution Equation
Since the units for molarity is mol.L1 which is in liters, you have to maintain that same unit when using M1V1=M2V2. If the question wants the answer in mL, you can always convert the answer you get to the needed unit.

 Posts: 56
 Joined: Wed Sep 30, 2020 9:33 pm
Re: Units for Dilution Equation
As you said, it doesn't matter if you're being consistent with your units. It may sometimes be easier to do your calculations in mL if the numbers in liters are too small, but make sure to convert your final answer to liters if you have to solve for molarity.
Re: Units for Dilution Equation
For values in the dilution equation, you can use mL or L as long as you keep the units consistent across all values you plug into the equation.
Re: Units for Dilution Equation
I noticed on the example in today's lecture that he keeps writing mol. L^1. We can just write mol/L when completing a problem with the M1V1 = M2V2 equation right?

 Posts: 74
 Joined: Wed Sep 30, 2020 9:35 pm
Re: Units for Dilution Equation
I think as long as we use same units for V1 and V2 using the equation, it is okay to use ml or units other than L.

 Posts: 91
 Joined: Wed Sep 30, 2020 9:46 pm
Re: Units for Dilution Equation
You should use Litters because molarity's units are in fact mol.L^1.

 Posts: 87
 Joined: Wed Sep 30, 2020 9:42 pm
 Been upvoted: 1 time
Re: Units for Dilution Equation
As long as the initial and final units are the same it doesn't matter whether you use mL or L. When you use mL, it's implied that you're basically multiplying both sides of the equation by 1000 to go from L to mL.

 Posts: 109
 Joined: Wed Sep 30, 2020 9:35 pm
Re: Units for Dilution Equation
I am pretty sure you can you either milliliters or liters as long as you have the same on both sides. When you calculate for one of the variables, you'll always end up with the right units if you do this because either Molar unit or the Volume unit will cancel out.

 Posts: 106
 Joined: Wed Sep 30, 2020 9:56 pm

 Posts: 98
 Joined: Wed Sep 30, 2020 10:01 pm
Re: Units for Dilution Equation
Vanessa Perez wrote:Quick question: is 0.987(10^4)L the same as 9.87(10^3)L??
No, they're not the same:
0.987 * 10^4 = 0.0000987, while 9.87 * 10^3 = 0.00987.
The negative exponent tells you how many spaces to the left you move the decimal point.

 Posts: 96
 Joined: Wed Sep 30, 2020 10:01 pm
Re: Units for Dilution Equation
replying to Vanessa:
No they are not. For the .987x10^4, it should not be written this way because proper scientific notation would be 9.87x10^5 because you have to move the decimal point over to the right by one so it would not be the same as 9.87x10^3.
.987x10^4 = .0000987
9.87x10^3 = .00987
No they are not. For the .987x10^4, it should not be written this way because proper scientific notation would be 9.87x10^5 because you have to move the decimal point over to the right by one so it would not be the same as 9.87x10^3.
.987x10^4 = .0000987
9.87x10^3 = .00987

 Posts: 109
 Joined: Wed Sep 30, 2020 9:35 pm
Re: Units for Dilution Equation
Vanessa Perez wrote:Quick question: is 0.987(10^4)L the same as 9.87(10^3)L??
They would be the same if the exponents were reversed:

 Posts: 104
 Joined: Wed Sep 30, 2020 9:58 pm
 Been upvoted: 1 time
Re: Units for Dilution Equation
For M1V1=M2V2, as long as the units are the same on either side (mL on both sides or L on both sides), it should work. The same would not work if you were finding molarity using M=n/V.
Re: Units for Dilution Equation
DMaya_3C wrote:I noticed on the example in today's lecture that he keeps writing mol. L^1. We can just write mol/L when completing a problem with the M1V1 = M2V2 equation right?
Yes, you can write it either way. They mean the same thing. It's just different notation.

 Posts: 164
 Joined: Wed Sep 30, 2020 9:46 pm
 Been upvoted: 1 time
Re: Units for Dilution Equation
For the example in the lecture about Dilution, Dr. Lavelle converted mL to liters when doing his calculations but then converted his final answer back to mL. Perhaps it is dependent on the question and the quantity of the answer. It would make more sense if you told someone to measure 15 mL of a solution instead of telling them to measure .015 liters.

 Posts: 90
 Joined: Wed Sep 30, 2020 9:32 pm
 Been upvoted: 1 time
Re: Units for Dilution Equation
Hi,
When using the dilution equation "M1V1 = M2V2" it is ensured to be used with the units of moles (mol) per liters of solution (L) as in "mol/L" for Molarity and liters (L) for Volume. With regards to mL, if the question asks for milliliters (mL) for an answer, be sure to use liters (L) in your calculations and convert to milliliters (1 L = 1,000 mL) at the final step.
Hope this helps! :)
When using the dilution equation "M1V1 = M2V2" it is ensured to be used with the units of moles (mol) per liters of solution (L) as in "mol/L" for Molarity and liters (L) for Volume. With regards to mL, if the question asks for milliliters (mL) for an answer, be sure to use liters (L) in your calculations and convert to milliliters (1 L = 1,000 mL) at the final step.
Hope this helps! :)

 Posts: 50
 Joined: Wed Sep 30, 2020 9:37 pm
Re: Units for Dilution Equation
I believe the unit doesn't matter if you're just concerning about the calculation. It's ok to use milliliters for volume. However, if you are tring to solve M, the unit should be in liters. (mol/L)

 Posts: 90
 Joined: Wed Sep 30, 2020 9:36 pm
 Been upvoted: 1 time
Re: Units for Dilution Equation
When solving for a dilution problem (M_{initial}V_{initial} = M_{final}V_{final}), it doesn't matter if you use mL or L as long as you keep the units consistent for V_{initial} and V_{final}. If you are solving for volume, and the problem specifies that you should use mL or L, then convert to those units. If you are solving for molarity, then the units you use for volume shouldn't matter (as long as the initial and final volume are consistent) because the units will cancel out in the calculations.

 Posts: 97
 Joined: Wed Sep 30, 2020 9:43 pm
Re: Units for Dilution Equation
Yes, it is ok to use mL in your calculations as long as you stay consistent throughout. Also, an added note is that if you are using the unit liters in your calculations and your final result is a very small number, it is often preferred to switch your final answer into mL...whichever units make the most sense based off of your judgement.

 Posts: 97
 Joined: Wed Sep 30, 2020 9:40 pm
Re: Units for Dilution Equation
As long a the units are the same on both sides, it doesn't matter. Make sure you give answer in the requested units though!
Return to “Molarity, Solutions, Dilutions”
Who is online
Users browsing this forum: No registered users and 1 guest