I know I posted this but you didn't answer! Please help!!!!
Consider the following reaction at 298 K:
C(graphite) +2Cl2 (g) -----> CCl4(l)
Calculate the following quantities.
Delta H: -139 kJ/mol
deltaS(sys)=? J/mol*K
deltaS(surr)=? J/mol*K
deltaS(univ)=? J/mol*K
My answer is:
deltaS(sys)=654.9J/mol*K
deltaS(surr)=0.4664 J/mol*K
deltaS(univ)=655.366J/mol*K
Is this right???????????
chemistry - DrBob222, Wednesday, March 14, 2012 at 11:20pm
Your tables may not be the same as mine but I looked and found
Cl2 for Cl2 = 223.0 J/mol
C(graphite) = 5.740
CCl4(l) = 216.4
If I use S products - S reactants that becomes 216.4 - 5.740 - (2*223.0) and I don't see anything in your answers close to that.
chemistry - Kelsey, Wednesday, March 14, 2012 at 11:41pm
So what are the answers for
deltaS(sys)=? J/mol*K
deltaS(surr)=? J/mol*K
deltaS(univ)=? J/mol*K
I need to verify the correct answers. Could you please tell me...Thanks!
chemistry - Kelsey, Wednesday, March 14, 2012 at 11:44pm
Also I don't know how you are working this problem out.
chemistry - Kelsey, Thursday, March 15, 2012 at 12:34am
DrBob222 could you please answer!!!!!!
chemistry - Kelsey, Thursday, March 15, 2012 at 1:16am
My answer is:
deltaS(sys)=654900J/mol*K
deltaS(surr)=466.4 J/mol*K
deltaS(univ)=655366J/mol*K
Sorry I forgot to convert to J
also I checked this problem and I only got thedeltaS(surr)=466.4 J/mol*K correct. Please help
also I checked this problem and I only got the deltaS(surr)=466.4 J/mol*K correct. Please help
I have dS for system =
216.4 - 5.74 -2(223.0) = ? J/mol = -235.3 J/mol Check that.
dS for surroundings = -dH/T = -(-139,000)/298 = 466.4 J/mol
dS total (universe) = dS sys + dS surr = -235.3J + 466.4 = ? check that.
Check the signs. Check the # s.f.
Everything is right except the system...i put -253.5 and it marked me wrong :(
I think u added wrong on accident
Wait never mind that's what i got as the answer....so why is it wrong?
The best advice I have is for you to verify those numbers from your text/notes. I took these from a text that is almost 20 years old; newer numbers may be in your text. That's what meant with my first post; I gave you the numbers I had and I hoped you would check them with your reference.
I am puzzled too. If the dS univ is ok and the dS surroundings is ok, how can the dS system be out of whack since dS univ = dS sys + dS surr
the answer is -235.5...you subtracted wrong! Thanks for the help :)
To calculate deltaS(sys) for this reaction, you need to determine the change in entropy for the system. The change in entropy is given by the difference between the entropy of the products and the entropy of the reactants.
First, we need to find the entropy values for each component in the reaction from a table or other reliable source.
- The entropy of C(graphite) is 5.740 J/mol*K.
- The entropy of Cl2(g) is 223.0 J/mol*K.
- The entropy of CCl4(l) is 216.4 J/mol*K.
Next, we can calculate deltaS(sys) using the equation:
deltaS(sys) = S(products) - S(reactants)
deltaS(sys) = (216.4 J/mol*K) - (5.740 J/mol*K + 2 * 223.0 J/mol*K)
Calculating this, we get:
deltaS(sys) = 216.4 J/mol*K - 5.740 J/mol*K - 446.0 J/mol*K
deltaS(sys) = -235.34 J/mol*K
So, the value for deltaS(sys) is -235.34 J/mol*K.
To find deltaS(surr), the change in entropy for the surroundings, you need information about the heat transfer for the reaction. If there is no information provided in the question, it is difficult to determine the value of deltaS(surr).
Finally, to find deltaS(univ), the change in entropy for the universe, you can use the equation:
deltaS(univ) = deltaS(sys) + deltaS(surr)
Given the information provided, deltaS(surr) is not known, so it is not possible to calculate deltaS(univ) accurately.
Based on the information provided, the answer for deltaS(sys) is not 654.9 J/mol*K as you stated. The correct value for deltaS(sys) is -235.34 J/mol*K.