Chemistry

Predict whether the following reactions will be exothermic or endothermic

A) N2(g)+ 3H2(g) --> 2NH3(g)
B) S(g) +O2(g) ---> SO2(g)
C) 2H2O(g) ---->2H2(g) + O2(g)
D) 2F(g) +F2(g)

Bond
H-H 432 kj/mol
N-N(triple bond) 942 kj/mol
O=O 494 KJ/Mol
F-F 155 KJ/mol
H-N 386 KJ/mol
H-O 459 kj/mol
S=O 522 KJ/mol

  1. 👍
  2. 👎
  3. 👁
  1. BE = bond energy
    BE reaction = BE for N2 + BE for 3*H2 - BE for 2*3(N-H)
    If BE rxn is -, exothermic
    If BE rxn is +, endothermic
    The others are done in a similar fashion.

    1. 👍
    2. 👎
  2. I got A) Exo
    B) Exo
    C) Endo
    D) Endo

    But its wrong :/ i have no idea what i am doing wrong.

    A) 942+3(432)-6(386)=-78
    B)494-522=-28
    C)4(459)-2(432)+494=478
    D)2(155)-155=155

    1. 👍
    2. 👎
  3. I know that A is an exothermic reaction.

    1. 👍
    2. 👎
  4. http://antoine.frostburg.edu/chem/senese/101/thermo/faq/enthalpy-from-bond-energies.shtml

    1. 👍
    2. 👎
  5. Yes, from general knowledge
    A is exothermic
    B is exothermic
    C is endothermic (the reverse reaction is exothermic!)
    D is the formation of F2(g) from its elements in their standard states. All elements in their standard states have a standard enthalpy of formation of zero, as there is no change involved in their formation. So D is neither exothermic or endothermic as
    deltaH(f)=0

    1. 👍
    2. 👎
  6. A B & C are correct
    D.Should say: 2F---Fsub2. Exothermic. One bond is formed F-F
    0-155= -155kJ/mol.

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Chemistry

    Can anyone help me with these three questions? Predict the sign of delta S° and then calculate delta S° for each of the following reactions a. 2H2S(g) + SO2(g) --> 3S(rhombic)(s) + 2H2O(g) b. 2SO3(g) --> 2SO2(g) +O2(g) c.

  2. chem

    a considerable amount of heat is required for the decomposition of aluminum oxide. 2Al2O3-> 4Al(s)+ 3O2(g) change in heat= 3352KJ a. what is the heat change for the formation of 1 mol of aluminum oxide from its elements? i got

  3. Chemistry

    Calculate Delta H for the reaction CH4(g)+NH3(g)-->HCN(g)+3H2(g) given, N2(g)+3H2(g)->2NH3(g) DeltaH=-91.8kj C(s)+2H2(g)->CH3(g) DeltaH=-74.9kj h2(g)+2C(s)+N2(g)->2HCN(g) DeltaH=270.3kj

  4. Chemistry

    Athletes often use instant cold packs to soothe injuries. Many of these packs use the dissociation of ammonium nitrate in water to create a cold-feeling compress. Is this reaction endothermic or exothermic? A. Endothermic because

  1. Chemistry- Dr.Bob222

    Predict the effect of decreasing the temperature on the position of the following equilibria. (a) H2(g) + Cl2(g) ↔ 2HCl(g) + 49.7 kJ My answer: shifts to the right (b) 2NH3(g) ↔ N2(g) + 3H2(g) ∆ H = 37.2 kJ My answer: shifts

  2. Science Help!

    A student made a list of reactions: Fireworks exploding Paper burning Cellular respiration How should the student title his or her list A. Double replacment reactions B. Single replacement reactions C. Endothermic reations D.

  3. Chemistry

    1. How many moles of ammonia NH3 are produced when 0.45 moles of nitrogen N2 reacts? N2 + 3H2 yields 2NH3 2. How many mililiters of water will be produced when 2.05 g of hydrogen reacts? The density of water is 1.00 g/mL ? 2H2 +

  4. chemistry

    For which of the reactions listed below will Gibbs free energy always be negative? A. An exothermic reaction that increases in entropy B. An endothermic reaction that decreases in entropy C. An endothermic reaction that increases

  1. Chemistry

    Is the solvation of borax in water an exothermic or endothermic process? i am thinking the it is endothermic...is that right?

  2. Chemistry

    Which of the following reactions is exothermic? 1. Na(s) --> Na(g) 2. Na(g) --> Na+ + e- 3. Cl2(g) --> 2Cl(g) 4. Cl(g) + e- --> Cl-1 My guess is 4, but I'm not sure Here is what you do. For 1, do we think it will take energy to

  3. Chemistry

    H2 and F2 react according to the following equation, forming HF. H2(g) + F2(g)  2HF(g); H° = –271 kJ If H2(g) and F2(g) were mixed in a thermally insulated vessel, the reaction that occurred would be a. endothermic, and

  4. CHEMISTRY

    Is this exothermic or endothermic? EXPLAIN C2H2+H2-----> C2H4 Is this exothermic or endothermic? EXPLAIN C2H2+2H2---->C2H6 Is this exothermic or endothermic? EXPLAIN C2H4+ H2 ----> C2H6

You can view more similar questions or ask a new question.