Asking for molarity of pure water

[TheMightyBoosh]

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I feel like this is a stupid question.

Passage 47, question #4 in the Chemistry section of the TPRH SW asks "what is the molarity of the water in a liter of pure water assuming that the density of water is 1.0 g per mL?

The solution explains that you solve this problem by dividing moles of H20 by liters of H20...

And I want to hit my head on the wall.

How can you solve for molarity, when molarity is defined as solute divided by solvent? My understanding is that you need a defined solute (something dissolving) before you can even talk about molarity. How does it make sense to consider water as a solute in water when the solvent and the solute are the same thing!?

 

[loveoforganic]

Eh, it's semantics. The question stem should have given you the idea of what you were supposed to do.

 

[TheMightyBoosh]

Yea but I was thrown off by the answer choices "undefined" and "0 M." Ugh.

 

[muhali3]

isn't the answer: [ (1000g) / (18 g/mol) ] / 1 L = 55.5 M

conceptually it doesn't make sense though

 

[loveoforganic]

Yea but I was thrown off by the answer choices "undefined" and "0 M." Ugh.

Ah. Well that's kind of weak. Well, at least it wasn't on the real thing!

Yeah that's the answer.

 

[JSU]

isn't the answer: [ (1000g) / (18 g/mol) ] / 1 L = 55.5 M

conceptually it doesn't make sense though

Yup, ive seen that before.