You normally take 2 Ibuprofen (C13H18O2) when you have pain. Each one is 250 g. How many moles of ibuprofen do you take?

2.4mol

Explanation:

In order to calculate numbers of moles we have to divide the given mass by the molar mass of the substance (ibuprofen) n= m/M

To calculate the molar mass we have

C13= 12*13= 156

H18= 1*18=18

O2= 16*2 =32

Molar mass M = 153+18+32= 206g

Given the mass m= 250g per tablet

Hence number of moles in one tablet is n= 250/206= 1.2 mol

Therefore the total number of ibuprofen you took is 1.2*2 (for the two tablets) = 2.4 moles

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"