. An excited hydrogen atom with an electron in the n 5 5 state emits light having a frequency of 6.90 3 1014 s21. Determine the principal quantum level for the final state in this electronic transition.

2

Explanation:

Given that the energy of a photon of light is obtained from;

ΔE = hf = 6.6 * 10^-34 Js * 6.903 * 10^14 = 45.6 * 10^-20 J

For moving from n=2 -n-=5 the electron absorbed energy hence the energy is positive.

but;

ΔE = -2.18 * 10^-18 (1/n^2final - 1/n^2initial)

45.6 * 10^-20 J= 2.18 * 10^-18 J (1/n^2final - 1/5^2)

0.21 =  (1/n^2final - 1/5^2)

1/n^2final = 0.21 + 1/5^2

n^2final = 4

nfinal = 2

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o