Iron has density 7.87 g/cm3. If 51.3 g of iron is added to 74.5 mL of water in a graduated cylinder, to what volume reading will the water level in the cylinder rise?

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A lot of chemistry is just figuring out how to turn one set of units into another set of units.  You figure out how to divide out the units you don't want and get the units you do want.  First, remember 1cm3=1mL.  You want to get rid of g and get mL.  Then, with density, I see it's in g/cm3 (or g/mL).  7.87 g/mL is the same as 7.87g1 mLThat means if I divide the mass by the density, it's the same as multiplying by 1 mL7.87 g(sorry for the weird formatting, it's hard showing math in this format).  With that in mind, here's how I'd solve it on my homework.51.3 g of iron= ?mL of iron (which will add to the H2O already in the cylinder)51.3g/7.87 g/cm3= 51.3/7.87   g/g/cm351.3 g of iron = 6.52 cm3 of iron= 6.52 mL of iron74.5 mL + 6.52 mL = 81.02 mL (sig figs= 81.0 mL)