The heat released when 1.00 g of ethanol (Mr = 46.0) undergoes complete combustion is

felz.zz

does anyone know how to get to the answer of 2.28 x 10^-18 ?

Reply 1

Old man1234

Value stated divide by (avagadros constant / 46)

Reply 2

LittleOrchid

Original post by felz.zz

does anyone know how to get to the answer of 2.28 x 10^-18 ?

Moles of ethanol} n=m/Mr so 1/46 = 0.021739

Therefore, 29.8x10^3 (from kJ to J) is equal to 0.021739 moles of ethanol

We want the molecules though so we need n = N/L where N is the number of molecules in the given moles
So, N = 0.021739/6.022x10^23 = 1.308x10^22 molecules

However, we want the heat released by ONE molecule so we need to divide the overall heat released by the amount of molecules:
29.8x10^3 / 1.308x10^22 = 2.278x10^-18 J (which rounds to 2.28x10^-18J)