Question

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

Answer 1

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"/"mL` not `g"/"mol`
`m= dv`
`m = (0.6548g"/"mL)(25.0 mL) = 16.37 g`
hexane formula is `C_6H_14` with molar mass of `86.18 g"/"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