1. 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) ΔH°f = ? The enthalpy change for the formation of PCl5 from the elements can be determined experimentally, as can the

    asked by Kat on May 1, 2011
  2. 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

    asked by Annie on January 31, 2013
  3. chemsitry

    c. Use the enthalpy diagram provided above and apply Hess’s Law to determine the standard enthalpy of formation for C12O36H20N12 (s) using the results from part (a) and the following values: The standard enthalpy of formation of gaseous carbon dioxide is

    asked by Nora on October 23, 2010
  4. chemistry

    The enthalpy of formation of C2H5OH is -238.7 kJ/mol. What information does this reveal about the bonds in the molecule? A. Bond formation in C2H5OH from its elements only occurs in cold temperatures. B. Bond formation in C2H5OH from its elements does not

    asked by Morgan on December 9, 2014
  5. 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) → 2NaOH (aq) + H2 (g) 2.Do

    asked by Cha-Ching on December 16, 2011
  6. 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 Hess’s Law to determine the standard enthalpy of formation for C12O36H20N12 (s) using the results from part (a) and the following

    asked by Vince on October 26, 2010
  7. Chemistry

    The enthalpy of formation for a substance corresponds to the enthalpy change for a reaction. Write the specific chemical reaction defining the enthalpy of formation of butane: Just checking to make sure this is correct: 4C + 5H2 ---> C4H10

    asked by AJ on March 26, 2017
  8. Chemistry

    Ammonia (NH3) boils at -33oC; at this temperature it has a density of 0.81 g/cm3. The enthalpy of formation of NH3(g) is -46.2kj/mol, and the enthalpy of vaporization of NH3(l) is 23.2 kJ/mol. Calculate the enthalpy change when 1 L of liquid NH3 is burned

    asked by Morgan on April 10, 2012
  9. 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

    asked by Farah on February 23, 2011
  10. Science

    The following heats of formation are used to find the change in enthalpy for the formation of tin chloride in the following reaction Sn (s) + 2Cl2(g) --> SnCl4(l).Sn(s) + Cl2(g) --> Sn Cl2(l) DH = -186.2 kJSnCl2(s) + Cl2(g) --> SnCl4(l) DH = -325.1 kJWhat

    asked by Mary on April 7, 2013
  11. 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

    asked by ABRAHAM on February 2, 2011
  12. chemistry

    2.9 The standard enthalpy of formation of the metallocene bis(benzene)chromium was measured in a calorimeter. It was found for the reaction Cr(C6H6)2(s) → Cr(s) + 2 C6H6(g) that . Find the corresponding reaction enthalpy and estimate the standard

    asked by girlgirl on June 18, 2011
  13. Chemistry

    What would you do in order to solve this question: "The enthalpy of combustion for benzoic acid is -3223.6kj/mol. Use the values of the standard enthalpies of formation of liquid water and CO2 to calculate standard enthalpy of formation of benzoic acid."

    asked by Kylie on November 29, 2014
  14. Chemistry

    Hydrazine, N2H4, is a colorless liquid used in rocket fuel. What is the enthalpy change for the process in which hydranzine is formed from its elements? N2(g) + H2(g) => N2H4(l) Use the following reactions and enthalpy changes: N2H4 + O2 => 2H2O DeltaH =

    asked by Austin on September 10, 2008
  15. chemistry

    A scientist measures the standard enthalpy change for the following reaction to be -172.4 kJ : 2SO2(g) + O2(g) 2SO3(g) Based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation of SO2(g) is

    asked by jojo on March 7, 2015
  16. chemistry

    A scientist measures the standard enthalpy change for the following reaction to be -2923.0 kJ : 2C2H6(g) + 7 O2(g) 4CO2(g) + 6 H2O(g) Based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation

    asked by Anonymous on October 24, 2012
  17. Chemistry

    If calcium carbide has a standard enthalpy of formation of -59.8 kJ/mol and acetylene has a standard enthalpy of formation of 226.73 kJ/mol, what is the standard enthalpy change for the reaction?

    asked by Kelly on February 20, 2013
  18. 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

    asked by Chris on January 31, 2007
  19. chemistry

    Carbon disulfide is a colorless liquid. When pure, it is nearly odorless, but the commercial product smells vile. Carbon disulfide is used in the manufacture of rayon and cellophane. The liquid burns as follows. CS2(l) + 3 O2(g) → CO2(g) + 2 SO2(g)

    asked by caroline on October 29, 2010
  20. 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

    asked by Anonymous on February 24, 2008
  21. ap chem

    calculate the lattice enthalpy of potassium fluoride from the following data: enthalpy of formation of K(g): +89 kJ · mol−1 first ionization energy of K(g): +418 kJ · mol−1 enthalpy of formation of F(g): +79 kJ · mol−1 electron affinity of F(g):

    asked by alexandra on July 13, 2010
  22. Chemistry

    N2 + O2 -> 2NO enthalpy change = +180.6kJ c) what is the enthalpy change for the formation of one mole of nitrogen monoxide? Okay, I know this question is super easy, but I don't know how to do it; if someone could please give me a detailed explaination on

    asked by A Canadian on February 6, 2013
  23. 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 VALUES TO CALCULATE

    asked by Anonymous on November 14, 2013
  24. 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

    asked by Anonymous on February 20, 2008
  25. chemistry

    A scientist measures the standard enthalpy change for the following reaction to be -53.4 kJ : Ca(OH)2(aq) + 2 HCl(aq) CaCl2(s) + 2 H2O(l) Based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of

    asked by Austin on March 18, 2012
  26. chemistry

    A scientist measures the standard enthalpy change for the following reaction to be -53.4 kJ : Ca(OH)2(aq) + 2 HCl(aq) CaCl2(s) + 2 H2O(l) Based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of

    asked by Austin on March 18, 2012
  27. Chemistry

    Which of the following is the best definition of Hess' Law? A. Heat evolved in a given process can be expressed as the sum of the heats of several processes that, when added, yield the process of interest. B. The enthalpy of a process is the difference

    asked by Jared on May 7, 2007
  28. Hess' law

    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. Since enthalpy is a state function, it will be different if a reaction takes place in one

    asked by christine on February 9, 2007
  29. 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:

    asked by Dan on November 19, 2007
  30. 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

    asked by Anonymous on November 14, 2013
  31. 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

    asked by Anonymous on November 14, 2013
  32. CHEMISTRY

    GIVE ENTHALPY PROFILE DIAGRAMS TO ILLUSTRATE ENDOTHERMIC AND EXOTHERMIC REACTIONS.INCLUDE AN EXPLANATION OF CONCEPTS SUCH AS ENTHALP CHANGE, ACTIVATION ENERGY AND CATALYSIS. EXPLAIN HOW THE PROCESSES OF BOND BREAKKAGE AND FORMATION DETERMINE THE ENTHALPY

    asked by ABRAHAM on February 1, 2011
  33. general chemistry

    A sample consisting of 0.025 mol of a solid compound is placed inside a metal cylinder. The cylinder was immersed in a water bath consisting of 10.00 kg of water at an original temperature of 25.00 °C. When the compound decomposes, the temperature of the

    asked by Nora on October 23, 2010
  34. Chemistry

    Consider the isomerization equlibria of an alkene (C4H8) that co-exists as three isomers. (These 3 are in an equlibrium triangle) Reaction 1: cis-2-butene ⇔ trans-2-butene Reaction 2: cis-2-butene ⇔ 2-methylpropene Reaction 3: trans-2-butene ⇔

    asked by Gleb on March 3, 2013
  35. 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,

    asked by Stuck on February 12, 2010
  36. AP Chemistry

    Under what circumstances is the enthalpy of formation of a compound from its elements usually: - positive - negative

    asked by Jesse on April 13, 2018
  37. 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

    asked by Alex on April 20, 2010
  38. Chemistry

    Why do we put a minus sing in front of the bond enthalpies of the bonds that are being formed? And why are the enthalpies of formation negative in general? I also don't understand why we subtract the enthalpy of formation of the reactants from the enthalpy

    asked by Anna on April 3, 2010
  39. chemistry

    comment that enthalpy of nutralization is merely the heat of formation one-one mole of liquid water

    asked by shaheer on April 8, 2013
  40. English

    This is a chemistry lab report, but I was wondering if someone could edit the grammar and look at the sentence structure, etc. I know it's really long and boring, but even if you just look over a bit of it, I would really appreciate it. And I'm assuming

    asked by a Canadian on February 21, 2013
  41. Chemistry*Dr.Bob

    I keep finding all sorts of different enthalpy of vaporizations for bromine. I used: 254.66 So factoring 254.66/2 into my equation below i ended up with a lattice energy of -863.33. Can you confirm this?

    asked by Crystal on February 2, 2011
  42. Chemistry Urgent

    Assuming that kerosene is C11H24, calculate the standard enthalpy change when 1 mole of kerosene burns completely in oxygen, using the data below: ΔH of formation of C11H24(l) = -327 kJ mol ΔH of formation of CO2(g)= -394 kJ mol ΔH of formation of H2O

    asked by Ava on March 9, 2014
  43. Chemistry

    I want to know the enthalpy change for this reaction which occurs in a blast furnace: Fe2O3(s) + 3C(s) --> 2Fe(l) + 3CO(g) You will need the heat of formation for CO, and ironIIIoxide, and the heatofmelting for iron. I suspect you have some temperature in

    asked by Alice on April 15, 2007
  44. Chemistry

    Caluclate the delta H for this reaction using standard enthalpies of formation. (The standard enthalpy of formation of liquid pentane is -146.8kJ/mol. Balanced equation balanced equation: C5H12(l)+8O2(g)-->5CO2+6H2O(g) CO2=393.5 H2O=40.7

    asked by Ashley on December 4, 2010
  45. 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 change

    asked by olexandra on April 19, 2010
  46. chemistry

    The standard enthalpy of formation for sulfur dioxide gas is -296.8 J. Calculate the amount of energy given off in kJ when 30.0 g of SO2 is fromed from its elements

    asked by adam on March 31, 2011
  47. Chemistry practice

    Using the form of energy diagram,make a concept map of the two different methods of calculation of reaction enthalpy(via the bond enthalpy and via the enthalpy of formation)

    asked by Gift on July 31, 2011
  48. 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)

    asked by Hailee on March 17, 2012
  49. Chemistry

    The standard change in internal energy for the combustion of buckyball is -25,968 kJ/mol. What is the enthalpy of combustion? What is the enthalpy of formation of buckyball? What is the molar enthalpy associated with converting buckyball to graphite? How

    asked by Joesph on September 28, 2016
  50. Thermodynamics

    The initial state consists of a closed system containing one mole of water (liquid) at 85°C and 1 atmosphere pressure. The immediate surroundings are also at 85°C and 1 atmosphere pressure. The change in state is described as this one mole of liquid

    asked by Elaine on October 3, 2013
  51. Chemistry (DrBob222)

    Hi, here's my (almost) 2-paged lab report introduction (hopefully you remember it from yesterday). I went to class today, and actually a lot of my other classmates' introductions were over 2 pages! Now I'm feeling kind of insecure about mine, and I'm not

    asked by a Canadian on February 19, 2013
  52. thermodynamics

    find change in enthalpy and change in entropy when liquid water at 30¡ãc is converted to steam at 40 bar,375¡ãc.

    asked by yajju on May 10, 2015
  53. AP Chemistry

    Calculate the entropy change when 4.44g of H2 reacts with O2 according to the reaction 2H2(g) + O2(g)→2H2O(ℓ) at 298 K and 1 atm pressure. The stan- dard molar enthalpy of formation of H 2O(ℓ) at 298 K is −285.8 kJ/mol. The corresponding free

    asked by Gabriella on October 29, 2013
  54. science

    the standard enthalpy of formation of ammonia is -46 kj/mol. if the enthalpy of formation of hydrogen molecule is -436 kj/mol and that of nitrogen molecule is -712 kj/mol find the average bond enthalpy of N-H bond in ammonia

    asked by bonnhi on April 1, 2014
  55. chemistry

    what is the standard enthalpy formation of liquid diethylamine (CH3CH2)2 NH? N2O5(g) + 8CH4(g) ==> 2(CH3CH2)2NH(l) +5H2O(l), delta H= -1103kJ

    asked by Ellie on June 21, 2010
  56. Chemistry

    Suppose 33.5 g of ClF3(g) and 29.1 g of Li(s) are mixed and allowed to react at atmospheric pressure and 25 C until one of the reactants is used up, producing LiCl(s) and LiF(s). Using the NIST value for the enthalpy of formation of ClF3

    asked by Katie on December 4, 2011
  57. Thermochemistry

    Suppose 23.6 g of ClF3(g) and 40 g of Li(s) are mixed and allowed to react at atmospheric pressure and 25 C until one of the reactants is used up, producing LiCl(s) and LiF(s). Using the NIST value for the enthalpy of formation of ClF3 (webbook.nist.gov),

    asked by LaurenB on December 3, 2011
  58. Chemistry

    1. The vapor pressure, P of a certain liquid was measured at two temperatures, T. from this data: T(K) and P(kpa) 275 3.57 825 6.57 for the enthalpy how would this be plotted on the graph point 1: point 2: 2. What is the rise, run, and slope 3. What is the

    asked by Josh on July 9, 2011
  59. Chemistry help

    I am not to sure how to approach the problem... Hydrazine is used as a rocket fuel because its reaction with oxygen is extremely exothermic: N2H4(liquid) + O2(g) ==> N2(g) + 2H2O(liquid) ΔH(reaction) = -615 kJ mol-1 What is the enthalpy of this reaction

    asked by Anonymous on May 11, 2014
  60. 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

    asked by Lucy on October 31, 2010
  61. 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

    asked by Annabelle on October 31, 2010
  62. 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

    asked by Lucy on October 31, 2010
  63. Chemistry

    What is the change in enthalpy when 17.0 g of liquid mercury is heated by 31°C?

    asked by Mike on March 12, 2013
  64. Chemistry

    Calculate the entropy change when 2.42 g of H2 reacts with O2 according to the reaction 2 H2(g) + O2(g) → 2 H2O(ℓ) at 298 K and 1 atm pressure. The standard molar enthalpy of formation of H2O(ℓ) at 298 K is −285.8 kJ/mol. The corresponding free

    asked by sam on October 14, 2012
  65. Chemistry

    Calculate the entropy change when 2.42 g of H2 reacts with O2 according to the reaction 2 H2(g) + O2(g) → 2 H2O(ℓ) at 298 K and 1 atm pressure. The standard molar enthalpy of formation of H2O(ℓ) at 298 K is −285.8 kJ/mol. The corresponding free

    asked by Austin on October 14, 2012
  66. Thermodynamics

    The initial state consists of a closed system containing one mole of super-heated liquid water at 115°C and 1 atmosphere pressure. The immediate surroundings are also at 115°C and 1 atmosphere pressure. The change in state is described as this one mole

    asked by Becca on February 23, 2013
  67. chemistry

    is this right? A formation equation... it shows the change in enthalpy that comes from forming one mole of the compound in its standard state.

    asked by trista on April 22, 2008
  68. chemistry

    a sample consisting 22.7g of a nongasous unstable compound X is placed inside a metal cylinder with a radius of 8Cm and a piston is carefully placed on the surface of the compound so that for all practical purposes the distance between the bottom of the

    asked by timmy on April 21, 2008
  69. Chemistry

    Calculate the standard internal energy change for the formation of water at 298K. The standard enthalpy of formation of water at 298K is - 285.8 KJ/mol.

    asked by Rohit on March 25, 2016
  70. sciences

    1. Liquid phosphorus trichloride, PCl3 is made by the direct combination of phosphorus and chlorine a. What is the maximum mass of PCl3 that can be produced from 125 g of P4 and 323 g Cl2? b. What mass of P4 remains after the reaction?

    asked by wesley on August 23, 2016
  71. science

    1. Liquid phosphorus trichloride, PCl3 is made by the direct combination of phosphorus and chlorine. a. What is the maximum mass of PCl3 that can be produced from 125 g of P4 and 323 g Cl2? b. What mass of P4 remains after the reaction?

    asked by wesley on August 23, 2016
  72. AP Chem

    Need help with this practice problem. I got the values for the gas to liquid and liquid to solid. Don't know how to do the rest? Heat of Vap and fusion too? No idea! What is the enthalpy change during the process in which 100.0 g of water at 50.0 C is

    asked by Chemkid on February 23, 2013
  73. AP Chem

    Need help with this practice problem. I got the values for the gas to liquid and liquid to solid. Don't know how to do the rest? Heat of Vap and fusion too? No idea! What is the enthalpy change during the process in which 100.0 g of water at 50.0 C is

    asked by Chemkid on February 23, 2013
  74. 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

    asked by Anna on September 20, 2009
  75. Chemistry

    The enthalpy of combustion of butane C4H10 is described by the reaction: C4H10(g) + (13/2) O2(g) -> 4CO2(g) + 5H2O(g) ΔH°rxn = –2613 kJ/mol Given the following enthalpies of formation: ΔH°f[CO2(g)] = -393.5 kJ/mol ΔH°f[H2O(g)] = -241.8 kJ/mol

    asked by anon on March 18, 2017
  76. Chemistry

    What is the enthalpy change (in kJ/mol) for the following process? Na+(g) + Br-(g) --> NaBr (s) Hint: use the Born-Haber cycle Note: the reference state for Br2 is Br2(l) not Br2(g) Data (in kJ/mol): enthalpy of sublimation of Na(s): 107 standard enthalpy

    asked by Crystal on February 1, 2011
  77. Chemistry Equations

    What's the equation for the formation of NO2(g) from its elements in its standard states? What's the equation for the formation of BF3(g) from its elements in its standard states? What's the equation for the formation of C2H5OH(l) from its elements in its

    asked by Kyle on November 5, 2009
  78. UW River Falls

    Calculate the enthalpy change, , for the process in which 40.0 of water is converted from liquid at 12.8 to vapor at 25.0.

    asked by Anonymous on November 5, 2010
  79. AP Chemistry

    Calculate the entropy change when 4.88 g of H2 reacts with O2 according to the reaction 2H2(g) + O2(g)→2H2O(ℓ)at 298 K and 1 atm pressure. The standard molar enthalpy of formation of H2O(ℓ)at 298 K is −285.8 kJ/mol. The corresponding free energy of

    asked by Ethan on January 20, 2015
  80. chemistry

    I need to do this question but um unable to draw the enthalpy cycle please help me. The standard enthalpy of combustion of C3H7OH(l), C(s,graphite) and H2(g) are -1300,-393, and -286 kJmol-1. Calculate the standard enthalpy of formation of C3H7OH(l)

    asked by isu on February 4, 2015
  81. Chemistry

    The following reaction has a standard enthalpy of reaction of -146.0 kJ/mol: Cu2O(s) + 1/2 O2(g) -> 2CuO(s) The standard enthalpy of formation of Cu2O(s) is -168.6 kJ/mol. What is the standard enthalpy of formation of CuO(s)?

    asked by James on March 11, 2011
  82. chemistry

    if enthalpies for formation of p4o10, h2o and h3po4 are -2984, -285.9 and -1279 respectively calculate the enthalpy change using hess's law

    asked by mala on July 4, 2012
  83. chemistry

    2. Calculate the enthalpy change of combustion for ethene gas (C2H4) given the following enthalpy changes of formation: ΔHºf(C2H4)(g) = +52 kJ mol^-1 ΔHºf(CO2)(g) = -394 kJ mol^-1 ΔHºf(H2O)(g) = -286 kJ mol^-1

    asked by John on July 19, 2014
  84. Chemistry

    If the standard enthalpy of formation of PH3(g) is +5.4 kJ mol-1, calculate the reaction enthalpy for 2PH3(g)--->2P(s)+3H2(g)

    asked by Sam on October 20, 2012
  85. Thermochemistry

    The standard enthalpy of formation of n-octane is -249.95 kJ/mol. Compute the amount of heat liberated when 5.24 g of n-octane is burned completely with excess oxygen to form carbon dioxide and liquid water.

    asked by LaurenB on December 4, 2011
  86. chemistry

    Consider the information given below ΔH⁰/ kJmol-1 Enthalpy of lattice formation for CaF2 -2611 Enthalpy of hydration for Ca2+ ions -1650 Enthalpy of hydration for F- ions -506 Using the information given above, calculate the enthalpy of solution for

    asked by chansa on June 7, 2016
  87. Chemistry

    The vapor pressure, P, of a certain liquid was measured at two temperatures, T. Represented in a table: T (in Kelvin) ------- P(in kPa) [325] --------------- [4.00] [775] --------------- [8.59] What is the enthalpy of vaporization for this liquid? (Delta H

    asked by Eric on January 23, 2012
  88. chemistry

    a sample consisting 22.7g of a nongasous unstable compound X is placed inside a metal cylinder with a radius of 8Cm and a piston is carefully placed on the surface of the compound so that for all practical purposes the distance between the bottom of the

    asked by tom on April 20, 2008
  89. Science

    Which of these represents a chemical change? A) two compounds combining to form a mixture B) a mixture being separated into two elements C) a compound being separated into two elements D) an element changing state from solid to liquid

    asked by Help Needed on October 12, 2016
  90. Science

    Which of these represents a chemical change? A) two compounds combining to form a mixture B) a mixture being separated into two elements C) a compound being separated into two elements D) an element changing state from solid to liquid

    asked by Help Needed on October 12, 2016
  91. chemistry

    how would you go about calculating the change in H' of the reaction 2N2O 4NO2+O2 if you are given the H'of formation for N2O and NO2 but not the H' of formation for O2? is H' of O2 zero? if so why? and also how can you tell to use change in S'=sum(npS'p) -

    asked by john on April 19, 2010
  92. chemistry

    Hello, a few questions: Thanks so much! 1. The heat capacities of titanium and water are 0.522 J g-1 K-1 and 4.184 J g-1 K-1, respectively. What is the final temperature of the titanium-water mixture if a 175.0-g sample of titanium, initially at 90.0oC, is

    asked by abby on March 1, 2014
  93. chemistry

    As an ionic solid dissolves in water, the temperature of the solution increases. What best describes the enthalpy and entropy of the solution? A. The enthalpy change is negative, and the entropy decreases. B. The enthalpy change is negative, and the

    asked by Cortney on March 18, 2015
  94. chemistry

    As an ionic solid dissolves in water, the temperature of the solution increases. What best describes the enthalpy and entropy of the solution? A. The enthalpy change is negative, and the entropy decreases. B. The enthalpy change is negative, and the

    asked by Cortney on March 19, 2015
  95. science

    An antacid tablet added to a glass of water fizzes and bubbles as it mixes. Which of the indicators of a chemical change is represented in this scenario? formation of a gas change in color change in energy formation of a precipitate is it the last one?

    asked by Dianni on November 9, 2018
  96. Chemistry

    When 0.3212g of glucose was burned in bomb calorimeter of calorimeter constant 641J/K, the temperature rose by 7.943 K. Calculate a) the standard molar internal energy of combustion b) the standard enthalpy of combustion and c) the standard enthalpy of

    asked by Nadira on May 4, 2010
  97. Chemistry

    Substance A has a normal fusion point of ‑10.0 oC, an enthalpy of fusion = 150.0 J g^-1; specific heats for the solid and the liquid are 3.00 and 6.20 J g^-1 oC^-1, respectively. How much heat, in J, is required to change 150 grams of A from a solid at

    asked by Kale on November 8, 2011
  98. chemistry

    How much energy is required to decompose 765 g of PCl3, according to the reaction below? The molar mass of PCl3 is 137.32 g/mol and may be useful. 4 PCl3(g) → P4(s) + 6 Cl2(g), ΔH°rxn = +1207 kJ

    asked by yr on April 27, 2011
  99. CHEM PLEASE HELP

    calcualte the enthalpy change for the process in which 6.00g of steam at 100C is coverted to liquid water at a temperature of 35.0

    asked by Bethany on December 16, 2015
  100. Science

    How to calcualte the enthalpy change for the process in which 6.00g of steam at 100C is coverted to liquid water at a temperature of 35.0?

    asked by Bethany on December 16, 2015