2 Al(s) + 3 Cl2(g) → 2 AlCl3(s)

Question

Into a cylinder with a moveable piston (pressure stays constant), a piece of aluminum is placed and chlorine gas is added. After they react, the temperature inside the piston is considerable higher than its initial temperature, but the volume inside the piston is consideraby smaller. What are the signs of q and w for the reaction?

Energy change is the sum of heat and work: ΔE = q + w. Work is calculated by: w = -PΔV
What is the change in energy (in joules) if a reaction absorbs 72.2 J of heat and increases in volume from 0.250L to 0.750L at a constant pressure of 0.993 atm? Please include the correct sign with your numerical result.
(Note: Make sure your units are consistent when combining energy terms. The conversion factor you need is: 1 L·atm = 101.3 J)

A reaction is done in a coffee-cup calorimeter by mixing equal volumes of reactants. If the initial temperature of the reactant solutions before then are mixed is 24.0 oC and the final temperature of the solution after the reaction has occurred is 22.2 oC, we can say that the reaction is __________ and the heat of reaction, ∆Hrxn , is written the a ___________ sign. For this reaction the enthalpy content of the products is ___________ than that of the reactants. Select the correct answers from the list below.

Answer 1

I'm gonna try the second one
delta V = 0.750 L- 0.250L
= 0.50 L
P= 0.933atm

w= -Pdelta V
w = - 0.993 atm *0.50 L
w= - 0.4965 atm *L

In Joules:
-0.4965 L* atm *101.3 J/ 1 L*atm= -50.31 joules
I think -50.31 joules of work is done (since energy is absored q is positive)

Answer 2

q is - since T is higher (exothermic).

w is - since work is done ON the system.