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April 19, 2014

Search: Calculate the enthalpy change (delta H..

Number of results: 44,019

CHEMISTRY
I know I posted this question before, but can you clarify it?? MY QUESTION IS AFTER YOU SWITCHED THE DELTA H1 THE CHANGE IN THE ENTHALPY IS NEGATIVE.... BUT THAT DOES NOT MAKE SENSE BECAUSE THE CHANGE IN ENTHALPY OF THE ORIGINAL DELTA H1 IS NEGATIVE(ACCORDING TO THE ...
Thursday, November 14, 2013 at 6:43pm by Anonymous

Chemistry
I know I posted this question before, but can you clarify it?? MY QUESTION IS AFTER YOU SWITCHED THE DELTA H1 THE CHANGE IN THE ENTHALPY IS NEGATIVE.... BUT THAT DOES NOT MAKE SENSE BECAUSE THE CHANGE IN ENTHALPY OF THE ORIGINAL DELTA H1 IS NEGATIVE(ACCORDING TO THE ...
Thursday, November 14, 2013 at 7:32pm by Anonymous

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 -241.8 kJ/mol. The product is 180.16gH2O=10....
Sunday, November 23, 2008 at 12:44pm by Mark

Chemistry
Please explain. The enthalpy changes for two different hydrogenation reactions of C2H2 are: C2H2+H2---->C2H4 Delta H 1 C2H2+2H2---->C2H6 Delta H 2 Which expression represents the enthalpy change for the reaction below? C2H4+H2---->C2H6 Delta H = ? A. Delta H 1 + ...
Monday, November 11, 2013 at 5:29pm by Anonymous

CHEMISTRY
Please explain. The enthalpy changes for two different hydrogenation reactions of C2H2 are: C2H2+H2---->C2H4 Delta H 1 C2H2+2H2---->C2H6 Delta H 2 Which expression represents the enthalpy change for the reaction below? C2H4+H2---->C2H6 Delta H = ? A. Delta H 1 + Delta...
Monday, November 11, 2013 at 6:39pm by Anonymous

chemistry
Calculate the enthalpy of change, Delta H of rxn, for each of the reactions. record the values in the data table part 2 I calculated the heat of rxn of the HCl +NaOH------NaCl + H2O. How do i go from here to enthalpy of change
Sunday, January 8, 2012 at 12:08pm by AP Chemistry Question

Chemistry - Enthalpy change and stoichiometry
N2 + O2 = 2NO enthalpy change = +180.6kJ c) what is the enthalpy change for the formation of one mole of nitrogen monoxide? d) What is the enthalpy change for the reaction of 1.000 * 10^2g of nitrogen with sufficient oxygen? I do not understand how to calculate the above, can ...
Wednesday, February 23, 2011 at 5:26am by Farah

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 -241.8 kJ/mol. The product is 180.16gH2O=10....
Sunday, November 23, 2008 at 9:33pm by Elizabeth

AP Chemisty
N2(g)+3F2 yields 2Nf3(g) Delta H(degree)298=-264KJ mol-1;Delta S(degree)298=-278J K-1 mol-1 The following questions relate to the synthesis reaction represented by the chemical equation above. a.)CAlculate the value of the standard free energy change, Delta G(degree)298, for ...
Thursday, June 7, 2007 at 3:25pm by Jenna

CHEM
Can you please check my work? I got -4.3KJ/mol If this is not right can you tell me what I am doing wrong? Thank you! Questions. 1.a. Use Hess's Law and the measured mean enthalpy changes for the NaOH-HCl and NH3-HCl reactions to calculate the enthalpy change to be expected ...
Friday, November 8, 2013 at 3:45pm by Lauren

Chemistry
Calculate the enthalpy change (delta H) in kJ for the following reaction. 2Al(s) + Fe2O3 (s) ==> 2 Fe(s) + Al2O3(s) use enthalpy changes for the combustion of aluminum and iron. 2Al(s) + 3/2 O2(g) ==> Al2O3(s) Delta H: -1669.8 kJ 2Fe(s) + 3/2 O2(g) ==> Fe2O3 (s) Delta...
Sunday, May 23, 2010 at 6:09pm by Kim

Chemistry
Calculate the enthalpy change (delta H) in kJ for the following reaction. 2Al(s) + Fe2O3 (s) ==> 2 Fe(s) + Al2O3(s) use enthalpy changes for the combustion of aluminum and iron. 2Al(s) + 3/2 O2(g) ==> Al2O3(s) Delta H: -1669.8 kJ 2Fe(s) + 3/2 O2(g) ==> Fe2O3 (s) Delta...
Sunday, May 23, 2010 at 9:53pm by Kim

DrBob222 PLEASE HELP!
************The values I used C(graphite): change in delta Hf=0 change in delta G= 0 change in delta S= 5.7 Cl2 change in delta Hf=0 change in delta G= 0 change in delta S= 223.1 CCl4 change in delta Hf=-139 change in delta G= -68.6 change in delta S= 214.4
Saturday, March 17, 2012 at 3:31pm by Leila

Chemistry
"Translate the empirical molar enthalpy given below into a balanced chemical equation, including the enthalpy change (delta H): The standard molar enthalpy of formation for carbon disulfide is 89.0 kJ/mol" I got delta H = 178 kJ (is that right?). However, I'm having trouble ...
Friday, February 12, 2010 at 4:18pm by Stuck

12 Chemistry
What is the molar enthalpy of combustion of magnesium? This was the lab question that I was asked to find after performing a lab based on Hess' law. I can't find anywhere in my notes how to calculate this, and the text book doesn't explain their steps properly, and I have ...
Saturday, March 29, 2008 at 10:58am by Chase (sorry if this long)

Chemistry
CONTINUE>>>>>>>>>>> The enthalpy changes for two different hydrogenation reactions of C2H2 are: C2H2+H2---->C2H4 Delta H 1 (there is a degree sign....standard enthalpy of formation??) *****WAIT A SECOND, IF I USE THE HEAT OF FORMATION ...
Thursday, November 14, 2013 at 8:45pm by Anonymous

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 enthalpy change of reaction per mole of ...
Tuesday, April 20, 2010 at 10:00am by Alex

chemistry
Consider the gold-platinum system which has a value of delta w of -4250 J/mole; (a) Calculate the enthalpy of mixing for a solution of 10% platinum and 90% gold. Express your answer in units of kJ/mole. (b) Is the dissolution of 10% platinum into gold an endothermic or an ...
Saturday, May 4, 2013 at 6:24am by ssss

Chemistry
Consider the gold-platinum system which has a value of delta w of -4250 J/mole; (a) Calculate the enthalpy of mixing for a solution of 10% platinum and 90% gold. Express your answer in units of kJ/mole. (b) Is the dissolution of 10% platinum into gold an endothermic or an ...
Tuesday, December 11, 2012 at 3:45am by Odesa

Chemistry
Consider the gold-platinum system which has a value of delta w of -4250 J/mole; (a) Calculate the enthalpy of mixing for a solution of 10% platinum and 90% gold. Express your answer in units of kJ/mole. (b) Is the dissolution of 10% platinum into gold an endothermic or an ...
Thursday, December 13, 2012 at 3:09am by Ling

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) + O2(g) yield CO2(g) enthalpy change= -393.51 ...
Saturday, March 17, 2012 at 11:11am by Hailee

Chemistry
Calculate the DELTA H(rxn), DELTA S(rxn), DELTA S(universe), DELTA G(rxn). For each system below indicate whether DELTA S and DELTA H are positive or negative. Then indicate if the reaction is entropy driven, enthalpy driven or neither. C3H8(g) + 2O2(g) => 3CO2(g) + 4H2O(g)
Friday, September 19, 2008 at 1:43am by Zach

chemistry... HELP !!!!!!!
The average bond enthalpy for C__H is 413 kJ/mol. In other words, 413 kJ of energy is required to break a mole of CH into atoms: CH (g) ----> C(g) + H(g) delta H= 413 kJ Using this information, and enthalpy of C6H6=5535kJ, calculate the enthalpy change of the reaction: C6H6...
Sunday, November 18, 2012 at 12:40pm by sarah

Chemistry
Given 2Al2O3 (s) --> 4Al(s) + 3O2 (g) (standard enthalpy change= 3351.4 kJ) a) What is the heat of formation of aluminum oxide? How do I find heat of formation from standard enthalpy change? I know how to do it when I'm given enthalpy, but they aren't the same thing- ...
Wednesday, January 31, 2007 at 8:40pm by Chris

chemistry
Is delta U the change in energy? Then delta H = delta U + P*delta V Look for the processes in which the work (P*delta V) is zero (number of moles doesn't change or volume doesn't change). In that case, delta H = delta U.
Friday, December 18, 2009 at 5:36pm by DrBob222

chemistry
How to calculate enthalpy change of the following reaction? : S + 2h2o >>> so2 + 2h2 given: s+o2 >>> so2 - enthalpy change = -296.8 kJ h2 + 1/2o2 >> h20 enthalpy change= -285.8kj I was trying to solve it myself but i got confused.. i know i have to ...
Monday, April 19, 2010 at 9:32pm by olexandra

chemistry
use the following data to calculate the mean bond enthalpy values for the C-H and C-C bonds. CH4(g)-C(g) + 4H(g) standard enthalpy change is +1648 kj/mol C2H6(g)-2C(g) + 6H(g) standard enthalpy change is +2820 kj/mol
Friday, February 22, 2013 at 8:04am by Bliss

chem
calculate the change in enthalpy when 1.00g of hydrogen peroxide decomposes. H2O2(l) yields H2O(l)+ 1/2O2(g) (traingle)H- -98.2kj I will be happy to critique your thinking on this. help me? You know the delta H is for one mole decomposition. So figure the fraction of 1gram/one...
Thursday, April 12, 2007 at 10:04am by crystine cole

Chemistry
Calculate the enthalpy of the reaction 2B2H6 + 6O2=2B2O3 +6H2O given the following pertinent information: A. B2O3(s) + 2H2) )g) = 3O2 (g) + B2H6 (g), delta H= +2035kJ B. 2B (s) + 3H2 (g) =B2H6 (g), delta H= +36 kJ C. H2 (g) + 1/2)2 (g) =H2O (l), delta H=-285 D. H2O (l) = H2O (...
Sunday, April 22, 2012 at 3:27am by B

chemistry
Given the following reaction and enthalpy change, calculate the amount of heat for converting 100.4g of liquid water (18.02g/mole) to a vapor? delta H= +44kJ
Thursday, November 3, 2011 at 12:30pm by Teresa

Chemistry Help!!
C3H8 + 5O2 ==> 3CO2 + 4H2O I suppose you want the standard enthalpy change using delta Hf values. delta Hrxn = (n*DHfproducts)-(n*DHfreactants)
Wednesday, October 12, 2011 at 1:47pm by DrBob222

Chemistry 152
For a certain reaction, the enthalpy change is -148.5 kJ, the entropy change is 256 J/K, and the free energy change is -250.1 kJ. At what temperature is the reaction occurring, in C? Choose one answer. a. 85 b. 102 c. 124 d. 158 e. 210 I keep using equation delta G=delta H-T(...
Saturday, July 3, 2010 at 11:09am by Car

Chem
RXN #1: H2 (g) + O2 (g) --> H2O2 (l) ; delta-H =? Calculate the enthalpy change (delta-H1) for the reaction above (RXN #1) using the information below and Hess' Law. RXN A: H2O2 (l) --> H2O (l) + 1/2 O2 (g); delta-H=-98.0 kJ/mol RXN B: 2 H2 (g) + O2 --> 2 H2O (l); ...
Tuesday, July 12, 2011 at 10:58pm by Ally

Chemistry
Data: C(graphite) + O2(g) forms CO2 (ga) Delta H = -393.5kJ H2(g) + 1/2O2(g) forms H2O(l)Delta H = 285.8kJ. CH3OH(l) + 3/2O2(g)forms CO2(g) + 2H2O(l)Delta H = -726.4 Using data above, calculate the enthalpy change for the raction below C(graphite) + 2H2 +1/2 O2(g) forms CH3OH(l)
Wednesday, October 27, 2010 at 8:29am by lavonne

Chemistry
So if you find the enthalpy change for one reactant, it's the enthalpy change for the other reactant (and products??), i.e. you know the enthalpy change for the entire reaction? So enthalpy change of one reactant (or product also?) = enthalpy change of entire reaction?
Wednesday, February 20, 2013 at 7:38pm by a Canadian

Chemistry
If you can show me an example of one problem, I have no idea how to approach this. Calculate where the number 40.67 came from. Use the Clapeyron-Clausisus equation. Assuming that delta H vap does not change with temperature, this equation relates the change in vapor pressure ...
Sunday, February 26, 2012 at 6:47pm by Angel

Chemistry
Calculate the enthalpy change for the reaction: 2S(s) + 3O2(g) --> 2SO3(g) Use the following thermochemical equations: Reaction S(s) + O2(g) --> SO2(g) Delta H(in kJ) -296.8 2SO2(g) + O2(g) --> 2SO3(g) Delta H(in kJ) -197.0
Wednesday, October 13, 2010 at 8:06pm by Jordin

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 -241.8 kJ/mol. The product is 180.16gH2O=10....
Saturday, November 22, 2008 at 10:35pm by Mark

IB Chemistry
I based on the formular to calculate enthalpy change is equal to the bond enthalpy total for the reactants subtracting from the bond enthalpy for products.Hence,if the reaction is endothermic,then the bond enthalpy total for the reactants is greater than for the products
Thursday, February 28, 2013 at 11:57pm by chirikamo

Chemistry
calculate the enthalpy change in delta H foor heating 250 grams of liquid water from 0 degrees celcius to 100 degrees celcius.
Friday, February 11, 2011 at 7:21pm by Bri

Chemistry
avg rate = delta C/delta T delta C is change in concentration delta T is change in time. 0.113-0.1076 = change in C in molarity. 60 sec = change in time. divide for the answer.
Sunday, February 17, 2008 at 4:32pm by DrBob222

College (Enthalpy) - College
S(rhombic)+O2(g)--->SO2(g) change in H(rxn)= -296.06 kJ/mol S(monoclinic)+O2(g)--->SO2(g) change in H(rxn)= -296.36 kJ/mol 1. Calculate the enthalpy change for the transformation. S(rhombic)-->S(monoclinic) Our goal is to calculate the enthalpy change for the ...
Sunday, October 31, 2010 at 7:11pm by Lucy

Physics
1. If the change in position delta(x) is related to velocity v (w/ units of m/s) in the equation delta(x)=Av, the constant A has which dimension? a. m/s^2 b. m c. s d. m^2 2. If a is acceleration (m/s^2), delta(v) is change in velocity (m/s), delta(x) is change in position (m...
Saturday, August 29, 2009 at 2:48pm by anonymous

chemistry
HNO3 (g) + 4H2 (g) NH3 (g) + 3H2O (g)deltaH = -637 kJ Calculate the enthalpy change when one mole of hydrogen reacts and What is the enthalpy change when 10.00 g of ammonia is made to react with excess of steam to form nitric acid and hydrogen gases?
Saturday, March 8, 2008 at 1:56pm by cooper

chemistry
HNO3 (g) + 4H2 (g) ---> NH3 (g) + 3H2O (g) deltaH = -637 kJ Calculate the enthalpy change when one mole of hydrogen reacts; and What is the enthalpy change when 10.00 g of ammonia is made to react with excess of steam to form nitric acid and hydrogen gases?
Saturday, March 8, 2008 at 3:35pm by cooper

chem
HNO3 (g) + 4H2 (g) ---> NH3 (g) + 3H2O (g) deltaH = -637 kJ Calculate the enthalpy change when one mole of hydrogen reacts; and What is the enthalpy change when 10.00 g of ammonia is made to react with excess of steam to form nitric acid and hydrogen gases?
Saturday, March 8, 2008 at 8:39pm by Anonymous

Chemistry
calculate the enthalpy change for: (enthalpy of formation of aqueous sodium hydroxide is -469.60 kJ/mol. enthalpy of formation of liquid water is -285.8 kJ/mol) 2Na + 2H2O = 2 NaOH + H2
Thursday, January 31, 2013 at 9:09am by Annie

Chem
Change in enthalpy problem. Consider the reaction represented below. Referring to the data in the table below, calculate the standard enthalpy change for the reaction at 25 degrees C. O3(g)+NO(g)-->O2(g)+NO2(g) Standard enthalpy of formation in kJ/mol: O3(g) 143 NO(g) 90 ...
Monday, November 19, 2007 at 7:29pm by Dan

college chemistry-thermochemistry
i have one more question: I know this one has to do with hess's law but i'm not sure of how to get the enthalpy of vaporization? Clculate the enthalpy of vaporization of solid potassium bromide to a gas of ions, the process KBr--->K{+1}(g)+Br{-1}(g), from the following ...
Saturday, November 8, 2008 at 8:49pm by maryanne

college chemistry-thermochemistry
i have one more question: I know this one has to do with hess's law but i'm not sure of how to get the enthalpy of vaporization from this? Clculate the enthalpy of vaporization of solid potassium bromide to a gas of ions, the process KBr--->K{+1}(g)+Br{-1}(g), from the ...
Saturday, November 8, 2008 at 10:38pm by maryanne

Chemistry
"Given that the bond enthalpy of the carbon-oxygen bonds in carbon monoxide and carbon dioxide are 1073 kJ/mol and 743 kJ/mol respectively, and that of the bond in the oxygen molecule is 496 kJ/mol, calculate the enthalpy change for the combustion of 1 mole of carbon monoxide...
Thursday, April 8, 2010 at 10:54pm by Stuck

chemistry
Ok, I really need to know how to work problems like these so could someone please show me how to set it up?! Given this data: 1. C(graphite) + O2(g) produces CO2(g), delta H = -393.5 kJ 2. H2(g) + 1/2 O2(g) produces H2O(l), delta H = -285.8 kJ 3. Ch3OH(l) + 3/2 O2(g) produces ...
Tuesday, November 23, 2010 at 4:52pm by lavonne

Science: Chemistry - Enthalpy
The enthalpy change in the combustion of the hydrocarbon octane is delta H = -5.48 x 10^3 kJ/mol C8H18(l). How much heat, in kilojoules, is liberated per gallon of octane burned? (Density of octane = 0.703 g/mL; 1 gal = 3.785 L.)
Wednesday, June 8, 2011 at 2:00pm by Jackie

Chemistry
Enthalpy changes: H2O2(l) ----> H2O(l) + 1/2P2(g) delta H= -94.6kJ H2(g) + 1/2O2(g)----> H2O2 delta H= -286.0kJ Calculate the value on delta H for the reaction: H2(g) + H2O2(l)----> 2H2O(l)
Saturday, May 19, 2012 at 10:05pm by Megan

Chemistry
Give the enthalpy change and entropy change values shown below calculate the free energy change for this reaction at 25 degrees C using Gibbs free energy equation. How does this value compare to the free energy change using the standard free energy of formation data? delta H=-...
Wednesday, May 16, 2007 at 2:32pm by Christian

chemistry
How many enthalpy changes (Hs) would be required to calculate the total enthalpy change when ice at 0.0oC is turned to steam at 100.0oC?
Thursday, February 20, 2014 at 6:40pm by Anonymous

Chemistry
You wish to know the enthalpy change for the formation of liquid PCl3 from the elements shown below. P4(s) + 6 Cl2(g)--> 4 PCl3(l) ΔHf = ? The enthalpy change for the formation of PCl5 from the elements can be determined experimentally, as can the enthalpy change for ...
Sunday, May 1, 2011 at 10:53pm by Kat

Chemistry
Hydrogen sulfide, H2S is a foul smelling gas. It burns to form sulfur dioxide. 2H2S +3O2 ----> 2N2 +6H2O Delta H=-1036kJ Calculate the enthalpy change to burn 26.7 g of hydrogen sulfide.
Monday, October 29, 2007 at 11:45pm by Lauren

Chemistry
Calculate the entropy change in the surroundings when 1.00 mol N2O4(g) is formed from 2.00 mol NO2(g) under standard conditions at 298 K. I get +192 J/K. The book says -192 J/K. Here is my work, where am I going wrong? Standard Enthalpy of NO2(g) = 33.18 kJ/mol * 2 mol = 66.36...
Saturday, February 21, 2009 at 1:58pm by chemstudent

calculus
delta x is a small change in x. What you are doing is drawing a short line from (x,y) to (x+delta x, y at x + delta x) Then you are finding the slope of that line the derivative of f(x) is the limit of the slope of that line as delta x goes to zero. f(x+delta x) = 8 (x+delta x...
Thursday, September 18, 2008 at 12:34am by Anonymous

chemistry
give enthalpy profile diagrams to illustrate endothermic and exothermic reactions. include an explanation of cocepts such as enthalpy change, activation energy and catalysts.explain how the process of bond breakage and formation determine the enthalpy change of a reaction ...
Wednesday, February 2, 2011 at 12:24am by ABRAHAM

Chemistry
O3 + NO --> O2 + NO2 (all in gas state) Calculate the change in enthalpy for the reaction at room temp. using the following data ^Hf: O3 = 143 NO = 90 NO2 = 33 So, I have 143+90--> X + 33. I don't know what the enthalpy of O2 is. I assume you simply subtract the enthalpy...
Monday, February 18, 2008 at 6:56pm by Anonymous

Chemistry (Enthalpy)-College
Use equation 1 as is. Reverse equation 2 (change the sign) and add to equation 1. Add the delta Hs to arrive at the total delta H for the new reaction.
Sunday, October 31, 2010 at 7:10pm by DrBob222

Chemistry
What is the different b/n change in internal energy(^E) and enthalpy change(^H)? Under what circumestance are change in energy(^E) and enthalpy change(^H) nearly equal? Thanks for your helps.
Wednesday, January 11, 2012 at 7:42am by Ethio

Chemistry
Someone said, "Calculate the total delta H of the reaction and subtract the total delta H of the product from it. If you get a positive value, it radiates heat which means it's exothermic. If it is negative, heat is needed to get a reaction so it is endothermic." ...shouldn't ...
Monday, February 11, 2013 at 7:10am by A Canadian

Chemistry
Someone said, "Calculate the total delta H of the reaction and subtract the total delta H of the product from it. If you get a positive value, it radiates heat which means it's exothermic. If it is negative, heat is needed to get a reaction so it is endothermic." ...shouldn't...
Monday, February 11, 2013 at 6:54pm by A Canadian

chemistry
Determine the enthalpy for the partial combustion of methane to carbon monoxide- 2CH4(g) + 3O2(g) = 2CO(g) + 4H2O(l) from change in enthalpy (CH4,g) = -890. kJ mol-1 and change in enthalpy (CO,g) = -283.0 kJ mol-1
Sunday, September 20, 2009 at 9:21pm by Anna

chemistry
Delta E = delta H -p*delta V where work is p*delta v. So if delta v is zero, then there is no work and delta E = delta H = qp Note that when a reaction is at constant P, then a change in moles will result in a change in volume. For a) H2 + I2 ==>2HI The work is zero because...
Saturday, August 15, 2009 at 10:17am by DrBob222

Chem
The bond enthalpy of N2(g) is 418.0 kJ/mol. Calculate delta Hf for N(g).?
Saturday, October 2, 2010 at 11:23am by Trinh

chemistry
If someone could see if I have the right answers, and if I don't maybe give me some hints on what to do to get to the right answerr, please. 1. Calculate the heat required to raise the temperature of 150g of water by 25.0C. [For pure water specific heat capacity=4.18Jg^-1K^-1...
Tuesday, November 10, 2009 at 5:24pm by Anonymous

Chemistry
I am having trouble with this equation and calculating the enthalpy of formation. 2 NaHCO3 (s) --> Na2CO3 (s) + H2O (g) + CO2 (g) delta H129.2kj I get as far as this step and then I dont know what to do next. delta H= [1*delta H (Na2CO3) + 1* delta H(H2O (g)) + 1* delta H(...
Tuesday, April 30, 2013 at 9:27pm by Laura

chemistry
CH3OH(g) ----> CO(g) + 2H2 (g) (delta H =+90.7k) A) is heat absorbed or released in the course of this reaction? b) calculate the amount of heat transferred when 45.0g of CH3OH(g)is decomposed by this reaction at constant pressure. c) for a given sample of CH3OH, the ...
Monday, October 17, 2011 at 12:32am by Anna

Chemistry-College
S(rhombic)+O2(g)--->SO2(g) change in H(rxn)= -296.06 kJ/mol S(monoclinic)+O2(g)--->SO2(g) change in H(rxn)= -296.36 kJ/mol 1. Calculate the enthalpy change for the transformation. S(rhombic)-->S(monoclinic) Our goal is to calculate the enthalpy change for the ...
Sunday, October 31, 2010 at 7:04pm by Lucy

Chemistry
Which of the following is the best definition of Hess' Law? A. Since enthalpy is a state function, it will be different if a reaction takes place in one step or a series of steps. B. Heat is always released by the decomposition of 1 mole of a compound into its constitute ...
Sunday, February 24, 2008 at 7:01pm by Anonymous

Chemistry
given that: delta H [Cl(g)]=121.3 kJ*mol^(-1) delta H [C(g)]= 716.7 kJ*mol^(-1) delta H [CCl(subscript 4)(g)] =-95.7kJ*mol^(-1) calculate the average molar bond enthalpy of the carbon-chlorine bond in a CCl(subscript 4) molecule.
Monday, April 8, 2013 at 4:19am by anonymous

Chemistry- please help ASAP!!!! thank you
S(rhombic)+O2(g)--->SO2(g) change in H(rxn)= -296.06 kJ/mol S(monoclinic)+O2(g)--->SO2(g) change in H(rxn)= -296.36 kJ/mol 1. Calculate the enthalpy change for the transformation. S(rhombic)-->S(monoclinic) Our goal is to calculate the enthalpy change for the ...
Sunday, October 31, 2010 at 6:09pm by Annabelle

Chem
For the reaction, 3C2H2(g) ===> C6H6 at 25C, the standard enthalpy change is -631 kJ and the standard entropy change is -430 J/K, Calculate the standard free energy change (in kJ) at 25C. What is the formula that relates stand. entropy, enthalpy and free energy changes?
Sunday, March 30, 2008 at 6:10pm by Ginger

Chemistry II
Calculate the enthalpy change in kilojoules when 54.7g of MgCO3 decomposes according to the following equation: MgCO3 (s) into MgO (s) + CO2 (g) My delta H answer was 100.6 KJ but the real answer is 76.1 KJ. Can someone please help?
Sunday, November 29, 2009 at 6:33pm by Mandy

chemistry
Data: SO2(g)+ 1/2O2(gas)forms SO3(g)Delta H = -99.1 kJ. Given the above data, calculate the enthalpy change when 89.6 g of SO2 is converted to SO3. Is this a grams to moles conversion or what? I can't find any examples of this type of calculation.
Wednesday, October 27, 2010 at 8:22am by lavonne

Chemistry - Enthalpy change and stoichiometry
how to calculate enthapy change of products
Wednesday, February 23, 2011 at 5:26am by andrea

Chemistry
Part A Calculate the standard enthalpy change for the reaction 2A+B --->2C +2D Use the following data: Substance Delta H(kJ/mol) A -263 B -391 C +203 D -523 Express your answer in kilojoules. MY ANSWER FOR PART A: Delta H =277 kJ PART B----THIS ONE I NEED HELP ON Express ...
Thursday, June 16, 2011 at 12:59pm by tina

Chemistry
Part A Calculate the standard enthalpy change for the reaction 2A+B --->2C +2D Use the following data: Substance Delta H(kJ/mol) A -263 B -391 C +203 D -523 Express your answer in kilojoules. MY ANSWER FOR PART A: Delta H =277 kJ PART B----THIS ONE I NEED HELP ON Express ...
Thursday, June 16, 2011 at 1:00pm by tina

chemistry
the enthalpy change of a system is 1.25 x 10^5 J and the entropy change is 300 J/K. calculate the free energy change of the system at 290 K
Monday, February 7, 2011 at 10:53pm by blarkin

Chemistry
Enthalpy change of what? You have the delta H values for each equation written. Perhaps you need to clarify your question if this is not what you want.
Saturday, June 6, 2009 at 5:52pm by DrBob222

Chemistry
Calculate the change in internal energy at 1 atm & 25C. H2 (g) + 1/2 O2 (g) ---> H2O (l) delta(H)= -286 KJ/mol Okay so i started with the equation: delta(E) = delta(H) - RTdelta(n) P= 1 atm T= 298 K but i dont exactly know what to do from here..please help thank you.
Saturday, August 27, 2011 at 2:42pm by ChemLover

Chemistry
I'm trying to calculate the enthalpy of the reaction Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2 (g) however I cannot find the enthalpy of the compound MgCl2 (aq) and I cannot calculate the total enthalpy without it
Sunday, March 27, 2011 at 10:13pm by Kirstie

Chemistry
Calculate the change in the enthalpy of the reaction. C4H4(g)+2H2(g)===>C4H8(g) Use the following: change in enthalpy of combustion for: C4H4=-2341 kJ mol-1 H2=-286 kJ mol-1 C4H8=-2755 kJ mol-1
Sunday, October 25, 2009 at 9:30pm by Natalie

Chemistry
The standard enthalpies of formation of ions in aqueous solutions are obtained by arbitrarily assigning a value of zero to H ions;that is, delta H(f) [H+(aq)]=0 A.for this reaction: calculate delta H(f) for the Cl- ions. HCl(g) ==H2O==>H+(aq)+Cl-(aq) delta H= -74.9 kJ/mol (...
Sunday, October 31, 2010 at 9:54pm by Kristin

physical chemistry
1.) Calculate delta rH for the freezing of water at one bar and -10 degrees C. The heat capacities are H2O(s)=36.9 JK-1mol-1 and H2O(l)=74.5JK-1mol-1. delta H for freezing of water at 0 degree C is -6602Jmol-1 (assume C is independent of temperature). 2.) Assume the hot brick ...
Tuesday, February 21, 2012 at 5:03pm by nicole

Chemistry- college
The standard enthalpies of formation of ions in aqueous solutions are obtained by arbitrarily assigning a value of zero to H ions;that is, delta H(f) [H+(aq)]=0 A.for this reaction: calculate delta H(f) for the Cl- ions. HCl(g) ==H2O==>H+(aq)+Cl-(aq) delta H= -74.9 kJ/mol (...
Monday, November 1, 2010 at 10:19pm by Willy

Chemistry
Which of the following is the best definition of Hess' Law? A. Heat is always released by the decomposition of 1 mole of a compound into its constitute elements. B. The enthalpy of a process is the difference between the enthalpy of the products and the enthalpy of the ...
Wednesday, February 20, 2008 at 1:49pm by Anonymous

physics
Acceleration is Delta V, over Delta T which equals V2-V1, over Delta T Delta referring to the change in velocity and change in time
Friday, March 5, 2010 at 7:35pm by Mateo

Chemistry
I would multiply 877 x 0.067 = g Ag exposed. Change to moles Ag, use the equation to convert to kJ, then use delta E = delta m*c^2 and calculate delta m. Post your work if you get stuck.
Saturday, May 9, 2009 at 10:53pm by DrBob222

gen Chem
I've attempted this problem but not sure if i'm on the right track. Use the enthalpy diagram provided above and apply Hesss Law to determine the standard enthalpy of formation for C12O36H20N12 (s) using the results from part (a) and the following values: The standard enthalpy...
Tuesday, October 26, 2010 at 12:45am by Vince

chemistry
what two conditions must be met by a thermochemical equation so that its standard enthalpy change can be given the symbol delta Hf?
Tuesday, October 12, 2010 at 1:02am by Leslie

Gen Chem
Here is what I did for #1. delta G = delta H - T*delta S delta G - delta H + delta S + For high T, -Tdelta S is more negative which makes delta G more negative. Since it is already negative, raising T won't change the direction. I think reaction ii and iii are done the same.
Friday, March 28, 2008 at 9:55pm by DrBob222

Chemistry
If the standard enthalpy of combustion of octane, C8H18(l) is -5471 kJ/mol, calculate the enthalpy change when 1.00 kg of octane are burned. the molar mass of octane is 114 g/mol
Saturday, October 20, 2012 at 9:46pm by Sam

Thermodynamics
The initial state consists of a closed system containing one mole of water (liquid) at 85C and 1 atmosphere pressure. The immediate surroundings are also at 85C and 1 atmosphere pressure. The change in state is described as this one mole of liquid forming vapor at 85C, as ...
Thursday, October 3, 2013 at 3:33pm by Elaine

Gen Chem
If the standard enthalpy of combustion of octane, C8H18(l) is -5471 kJ/mol, calculate the enthalpy change when 1.00 kg of octane are burned. the molar mass of octane is 114 g/mol
Saturday, October 20, 2012 at 9:39pm by Sam

Gen Chem
If the standard enthalpy of combustion of octane, C8H18(l) is -5471 kJ/mol, calculate the enthalpy change when 1.00 kg of octane are burned. the molar mass of octane is 114 g/mol
Saturday, October 20, 2012 at 9:39pm by Sam

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