Question

1.             Given the equations:                          N₂(g) + O₂(g) ® 2NO(g)                    ∆H = +180.7 kJ

                                                                               

                                                                                2NO(g) + O₂(g) ® 2NO₂(g)              ∆H = -113.1 kJ

                                                                               

                                                                                2N₂O(g) ® 2N₂(g) + O₂(g)                ∆H = -163.2 kJ

Calculate the change in enthalpy for the reaction:       N₂O(g) + NO₂(g) ® 3NO(g)

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2.   An electron in a carbon atom makes a transition from n=2 to n=3.

a) Does this transition require energy or emit energy?

                                                             

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b) Can you calculate the amount of energy involved using E = -R_H/n² ?

Calculate ∆E or explain why this is invalid.

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3. Determine the wavelength of light (nm) emitted when an electron makes a transition from n= 5 to n=2 in a hydrogen atom. Show your work.

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Answer 1

1)

Lets number the reaction as 1, 2, 3, 4 from top to bottom

required reaction should be written in terms of other reaction

This is Hess Law

required reaction can be written as:

reaction 4 = +1 * (reaction 1) -0.5 * (reaction 2) +0.5 * (reaction 3)

So, deltaHo rxn for required reaction will be:

deltaHo rxn = +1 * deltaHo rxn(reaction 1) -0.5 * deltaHo rxn(reaction 2) +0.5 * deltaHo rxn(reaction 3)

= +1 * (180.7) -0.5 * (-113.1) +0.5 * (-163.2)

= 155.65 KJ/mol

Answer: 155.65 KJ/mol

Only 1 question at a time please