# chemistry

posted by Morgan

2C2H2(g) + 5O2(g)→4CO2(g) + 2H2O(g)

a. Determine the enthalpy change for the reaction.

ΔH = (4(-393.5)+ 2(-241.8)) – (2(227) + 5(0))

The enthalpy change is -2511.6.

b. Determine the entropy change for the reaction.

ΔS = (4(213.7)+ 2(188.7)) – (2(200.9) + 5(205))

The entropy change is -194.6.

my teacher told me that my answers were wrong. What did I do wrong?

1. DrBob222

Thank you for showing your work.
I don't see anything wrong with your set up or the numbers. Always check to see that you used the correct value from the tables. I suspect the problem is one of significant figures. I think the answer is -2512 kJ.
-1.574E3 - 0.4836E3 = -2.058E3 since that last 6 on 483.6 can't be used.
Add that to -454 kJ to obtain -2512 kJ.

2. zoey

I think the problem is your you shouldn't multiply the number of moles with the the elements number ,,,that's what I think ,,

## Similar Questions

1. ### Chemistry

Calculate the work involved if a reaction with an enthalpy change of -2418 kJ is carried out in a vessel with a mobile, frictionless piston. Other details: the reaction is H2(g) + 1/2Oxygen2(g) yields H2O(g) with enthalpy change of …
2. ### chemistry

How to calculate enthalpy change of the following reaction?
3. ### chemistry

Calculate enthalpy change of reaction for the combustion of gaseous ethanol. C2H5OH + 3O2 >> CO2 + 3H2O. Using standard molar enthalpies of formation. C2H5OH -235.3 ( it's negative sign) CO2 -393.5 H2O -241.8 (1) Calculate the …
4. ### CHEMISTRY

1.Calculate the enthalpy change (ΔHºrxn) for the following reaction: (The enthalpy of formation of aqueous sodium hydroxide is -469.60 kJ/mol. The enthalpy of formation of liquid water is -285.8 kJ/mol.) 2Na (s) + 2H2O (l) → …
5. ### Chemistry

Reposted: Use Hess's law to calculate the enthalpy change for the reaction: 3C(s) + 3H2(g) yield C3H6(g) Given the following thermochemical equations: 2C3H6(g) + 9O2(g) yield 6CO2(g) + 6H2O(l) enthalpy change= -4116.0 kJ/mol C(s) + …
6. ### chemistry 2

for the reaction 2C2H2(g)=>C6H6(l) at 25 C, the standard enthalpy change is -631 kJ and the standard entropy change is -430 J/K. calculate the standard free energy change at 25 C. show all work Help please!
7. ### Chemistry

Use standard enthalpies of formation to determine ΔHorxn for: 2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(l) Enter in kJ.
8. ### Chemistry

Find the change in internal energy for this reaction. Enter in kJ. 2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(l) Enthalpy of reaction= -2599 kJ
9. ### Chemistry

Oxyacetylene torches are fueled by the combustion of acetylene, C2H2. 2C2H2(g) + 5O2(g) --> 4 CO2(g) + 2H2O(g) If the enthalpy change for the reaction is -2511.14 kJ/molrxn, how much heat can be produced by the reaction of a. 2mol …
10. ### Chemistry

For the combustion of acetylene: 2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(g) ΔH = -2511 kJ What is the enthalpy change when 2.80 g of C2H2 (g) reacts with excess oxygen.

More Similar Questions