TBR Stoichiometry question

[circulus vitios]

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Example 1.22: What is the mass percent of a 1.0 m NaCl(aq) solution?

I get how they answer the question but they assume 1000 grams or 1 liter of water. I don't remember assuming anything when doing mass percent questions in gen chem. Is this normal or just a bad question?

 

[Cruzerthebruzer]

Misread, sorry.

 

[Swagster]

Example 1.22: What is the mass percent of a 1.0 m NaCl(aq) solution?

I get how they answer the question but they assume 1000 grams or 1 liter of water. I don't remember assuming anything when doing mass percent questions in gen chem. Is this normal or just a bad question?

The small m is for molality, not molarity. That's why they are using 1000 g H2O.

 

[circulus vitios]

The small m is for molality, not molarity. That's why they are using 1000 g H2O.

edit: You're right, I'm an idiot! I was thinking small m meant mol, which was confusing me because why the hell would it be a "1.0 mole" solution and why would I be conveniently assuming 1kg/1L of solvent. Thanks for clarifying.

 

[Swagster]

It's not molality or molarity, it's mole. As in "What is the mass percent of a 1.0 mol NaCl solution?"

edit: Or at least that's my understanding. Maybe I'm misreading it?

You are misreading it. A small m when describing solution (which the "aq" at the end says it is) refers to molality = moles solute/kg solvent. Look at the answer choices of the question right above it.