NEED HELP ASAP!
Calculate the molality of C2H5OH in a water solution that is prepared by mixing 50.0 mL of C2H5OH with 138.2 mL of H2O at 20 degrees Celsius. The density of the C2H5OH is 0.789 g/mL at 20 degrees Celsius.
A. 0.00620
B. 8.4
C. 0.161
D. 6.20
E. none of these

Question

NEED HELP ASAP!
Calculate the molality of C2H5OH in a water solution that is prepared by mixing 50.0 mL of C2H5OH with 138.2 mL of H2O at 20 degrees Celsius. The density of the C2H5OH is 0.789 g/mL at 20 degrees Celsius.
A. 0.00620
B. 8.4
C. 0.161
D. 6.20
E. none of these

preetha · Answer

What do you have so far?  And what is your hurry?  Hope this is not a timed test.

anonymous · Answer

No it's not. I have been struggling with this all day, and it's the last problem I need help with on my chapter set problems.

anonymous · Answer

I know how to calculate molality, but I can't figure out how to incorporate the density part.

preetha · Answer

SO density is g/ml of Ethanol.  That means, when you have 1 ml of ethanol, it has a mass of 0.789 g.  You actually have 50 ml of Ethanol.  Can you tell me how many g of ethanol and therefore how many moles of ethanol are present in they 50 ml of ethanol?

anonymous · Answer

39.45 grams and converted to moles would be .8557483731?

preetha · Answer

Now use that in the molality calculation.

anonymous · Answer

sorry, .8561197917 moles.

anonymous · Answer

I got 21.70138889

anonymous · Answer

But what about the temperatures it gave, and the water numbers?

anonymous · Answer

I got D. Is that right?