4C.7

[RRahimtoola1I]

How do you do this problem? I was using q = nH and q = mH but I am not getting the correct answer.

"(a)Atitsboilingpoint,thevaporizationof0.579molCH4(l) requires 4.76 kJ of heat. What is the enthalpy of vaporization of methane? (b) An electric heater was immersed in a flask of boiling ethanol, C2H5OH, and 22.45 g of ethanol was vaporized when 21.2 kJ of energy was supplied. What is the enthalpy of vaporiza- tion of ethanol?"

[Jessica Booth 2F]

You should be able to use q=n. For part a) = 4.76 KJ/ .579 mol = 8.22 KJ/mol. Part b is the same except you need to convert the mass given into moles using the molar mass.

[sophiavmr]

Why does q=n deltaH? I thought deltaH was equal to q

[Sidney Shah 3H]

need to multiply n times deltaH because q is dependent on the amount of moles present whereas enthalpy is for 1 mole of a substance