AAMC 7 question # 31

[MDtoBe777]

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OKay...this is a really easy dumb question. I'm either dividing wrong or just out of it.

Q: What is the molarity of pure acetone?
given: acetone 589g/mol
density=0.791g/ml
a) 1.36M
b) 13.6M
c) 45.9M
d) 73.4M

Okay..I got A..the right answer is B.

This is what I did:

(1mol/589g)*(0.791g/mL)*(1000mL/L)=791mol/589L = 1.36 M

what did I do wrong? 😕

 

[shad420w]

You have the wrong MW, its only 58 g/mol.... oops i make mistakes like this ALLL THE TIME 😱

 

[MDtoBe777]

OMG! I wrote it in the margin thinking that I copied it directly from the passage (58.0)..instead i wrote 580! Thats the 4the dumb mistake on this test...cost me a WHOLE POINT! Thanks so much...and also, I don't know what I thought...580..thats so big! haha...thanks again.

 

[joelmamchur]

I just finsihed marking AAMC 7 and realized I did the EXACT same thing... lol.