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DustyFart
05-7-2012, 04:52 PM
Ok so this is the final question to my homework, and I cannot get this question wrong. I think I know the correct answer but I want to be 100% sure. Now I know this may be an easy question to most of you guys, so don't make fun of me too much.

A sample of iron has a volume of 10.0 mL. The density of iron is 7.87 g/mL. Which is the correct expression to calculate the mass of the sample using dimensional analysis?

Here are the choices.

10.0 mL × (7.87 mL/1 g)
10.0 mL × (1 mL/7.87 g)
10.0 mL × (1 g/7.87 mL)
10.0 mL × (7.87 g/1 mL)

j-rodd123
05-7-2012, 04:54 PM
lol its the last one 10.0 mL x (7.87 g/1 mL)

DustyFart
05-7-2012, 04:55 PM
Thanks, I still might have more questions.

DustyFart
05-7-2012, 05:30 PM
Here's another one I'm stuck on

If the heat of fusion is 32.2 kJ/mol, the amount of heat energy required to melt 5.67 grams of FeO is -

5.32 kJ
2.54 kJ
18.3 kJ
3.26 kJ

iironiic
05-7-2012, 05:36 PM
You need to use the Periodic Table to find out how many grams of FeO is in one mole. Then once you do this, multiply the heat of fusion with this ratio and you get the answer.

DustyFart
05-7-2012, 05:39 PM