(a)how much energy in KJ/mol is released when an electron makes a transition from n=5 to n=2 in a hydrogen atom?

User Icon for DrBob222 DrBob222 answered
11 years ago

E = 2.18E-18(1/4 - 1/25)

That is E in J/atom
That x 6.02E23 = E in J/mol
Then convert to kJ.
1/4 = 1/n^2
1/25 = 1/5^2

User Icon for Step-by-Step Bot Step-by-Step Bot answered
1 year ago

To calculate the energy released when an electron transitions from n=5 to n=2 in a hydrogen atom, we can use the formula for the energy of an electron in the hydrogen atom:

E = - 13.6 eV / n^2

Where:
E is the energy of the electron transition in electron volts (eV)
n is the principal quantum number

First, we need to calculate the energy of the electron when it is in the initial state (n=5):

E1 = -13.6 eV / 5^2 = -13.6 eV / 25 = -0.544 eV

Next, we calculate the energy of the electron when it is in the final state (n=2):

E2 = -13.6 eV / 2^2 = -13.6 eV / 4 = -3.4 eV

Now, we can calculate the energy difference between the two states:

ΔE = E2 - E1 = (-3.4 eV) - (-0.544 eV) = -2.856 eV

Finally, we convert the energy difference from electron volts (eV) to kilojoules per mole (kJ/mol). The conversion factor is 1 eV = 96.485 kJ/mol:

ΔE = -2.856 eV x 96.485 kJ/mol/eV ≈ -275.89 kJ/mol

Therefore, approximately 275.89 kJ/mol of energy is released when an electron transitions from n=5 to n=2 in a hydrogen atom. Note that the negative sign indicates the release of energy.

User Icon for Explain Bot Explain Bot answered
11 months ago

To calculate the energy released when an electron moves between energy levels in a hydrogen atom, we can use the equation:

ΔE = - R * (1/n²f - 1/n²i)

Where:
ΔE represents the change in energy
R is the Rydberg constant (2.179 × 10⁻¹⁸ J)
n₂ (final energy level) is 2
n₅ (initial energy level) is 5

First, let's convert the Rydberg constant (R) from joules (J) to kilojoules (kJ):
R = 2.179 × 10⁻¹⁸ J = 2.179 × 10⁻²⁵ kJ

Now, we can substitute the values into the equation and calculate ΔE:

ΔE = - (2.179 × 10⁻²⁵ kJ) * (1/2² - 1/5²)
= - (2.179 × 10⁻²⁵ kJ) * (1/4 - 1/25)
= - (2.179 × 10⁻²⁵ kJ) * (25/100 - 4/100)
= - (2.179 × 10⁻²⁵ kJ) * (21/100)

Calculating the result:
ΔE = - 4.5779 × 10⁻²⁶ kJ

Therefore, approximately 4.5779 × 10⁻²⁶ kJ of energy is released when an electron makes a transition from n=5 to n=2 in a hydrogen atom.