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View Full Version : Density and conversions for chemistry.


notsmartypants
Feb 21, 2009, 10:20 PM
I don't understand to to start these problems out.. Please help!!
Here they are:
The density of CCL4(carbon tetrachloride) is 1.58 g/mL.
What is the mass of 95.7 mL CCL4?

What is the volume of 227g of olive oil if its desity is 0.92 g/mL?

If you have an explanation or telling me how you did the problem then that would be great because I would like to know how you did it.
Thanks

Perito
Feb 22, 2009, 05:30 AM
You can often treat 'dimensions' as if they were numbers. This is called "dimensional analysis". You can determine what to do by the result of the dimensional analysis. This is an example.

#1 Density is in grams / mL. grams is on the top, mL is on the bottom of the fraction.

If you multiply grams / mL by mL, you'll get grams.

g/mL * mL = g

The mL "cancels out" and you end up with grams.


#2 If you have a weight of a material and its density then, by the same logic,

g divided by g/mL gives g * mL/g (remember that when dividing fractions, you can invert the divisor and multiply). The "g" cancels out and you're left with mL. So, simly divide 227 g by 0.92 g/mL and you have your answer.