Wording when answering molarity questions

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EMurphy_2L
Posts: 128
Joined: Sat Sep 07, 2019 12:16 am

Wording when answering molarity questions

Postby EMurphy_2L » Wed Oct 02, 2019 11:15 pm

I'm having trouble wording the answers to molarity questions in a logical, reality based way.
ie: What volume of (x) should be diluted to 150ml with water to reduce its concentration to (y)?
so would the answer of 4.5ml be 4.5ml of water added or ml of the molecule given? or what?

ie: An experiment requires the use of 60ml of a low molarity but there exists only a high molarity sample. How can the original, required molarity be prepared?
would I say "the existing substance should be diluted to 12ml for the experiment"?

I'm not sure if my question is clear but any help would be appreciated! I'm not having any computational difficulty, just conceptual for wording and meaning.

Angus Wu_4G
Posts: 102
Joined: Fri Aug 02, 2019 12:15 am

Re: Wording when answering molarity questions

Postby Angus Wu_4G » Wed Oct 02, 2019 11:30 pm

For the first example you listed, the answer would be "You would need 4.5mL of solution with concentration (something). "

For the second example you listed, you would say "You can prepare the required solution by adding 12mL of pure water to the original molarity sample."

I hope this is helpful. If it isn't, perhaps I am not understanding your question correctly.

Sarah Nichols 4C
Posts: 52
Joined: Sat Aug 24, 2019 12:18 am

Re: Wording when answering molarity questions

Postby Sarah Nichols 4C » Thu Oct 03, 2019 10:22 am

For the first example, I think the confusion is that when doing dilutions, you are starting with a stock solution with some concentration of a substance already dissolved. So you would use M1V1=M2V2 with the molarity of the original substance given in the question, along with the desired new volume and concentration, to find V1, which is the volume you need to start with of the stock solution (so in your example, you would say 4.5 mL of the original solution is needed)
Hope this helps!


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