How many molecules of hexane are contained in 25.0mL of hexane? The density of hexane at room temperature is 0.6548g/mol.

1 Answer
Jan 26, 2018

Rearrange density formula to solve for mass of hexane in grams, and then divide by molar mass of hexane to convert to moles of hexane. Then multiply by Avogadro's number

Explanation:

first of all, you have an inappropriate unit for density, the correct unit is g"/"mLg/mL not g"/"molg/mol
m= dvm=dv
m = (0.6548g"/"mL)(25.0 mL) = 16.37 gm=(0.6548g/mL)(25.0mL)=16.37g
hexane formula is C_6H_14C6H14 with molar mass of 86.18 g"/"mol86.18g/mol
mol hexane = (16.37 g)/(86.18 g"/"mol) = 0.1900 \ mol hexane
molecules of hexane = (0.1900mol)(6.023 "molecules""/"mol) = 1.144 * 10^23 molecules