At a given temperature, pentane with a vapor pressure of 624 torr is mixed with hexane with a vapor pressure of 437 torr. In the solution, the mole fraction of pentane is 0.3 and the mole fraction of hexane is 0.7. Which of the following is true about the mole fraction of pentane in the vapor? a. It is greater than 0.3
b. It is less than 0.3
c. It is equal to 0.3

answer is a

explanation:

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

the answers are

c and c