When electromagnetic radiation of wavelength 300nm falls on the surface of sodium electrons are emitted with a ke of 1.68 * 10 5 j mol -1 .what is the minimum energy needed to remove an electron from sodium? what is the maximum wavelength that will cause a photoelectron to move

3.83 × 10⁻¹⁹ J;  518 nm  

Step-by-step explanation:

The equation for the photoelectric effect is

hf = Φ + KE  

Data:

λ = 300 nm = 300 × 10⁻⁹ m

KE = 1.68 × 10⁵ J/mol

Calculations:

Part 1. Minimum energy to remove an electron

(a) Calculate the energy of the photon

fλ = c  

 f = c/λ     Divide each side by λ

E = hf

E = hc/λ

E = (6.626× 10⁻³⁴ × 2.998 × 10⁸)/(300 × 10⁻⁹)

E = 6.622 × 10⁻¹⁹ J

(b) Calculate the KE of one electron

KE = 1.68 × 10⁵ × 1/(6.022 × 10²³)

KE = 2.790 × 10⁻¹⁹ J

(c) Calculate the work function

hf = Φ + KE     Subtract KE from each side

Φ = 6.622 × 10⁻¹⁹  - 2.790 × 10⁻¹⁹

Φ = 3.83 × 10⁻¹⁹ J

The minimum energy to remove an electron from a sodium atom

is 3.83 × 10⁻¹⁹ J.

Part 2. Maximum wavelength to remove an electron

The photon must have just enough energy to overcome the work function and leave the electron with zero kinetic energy.

    E = Φ

hc/λ = Φ                      Multiply each side by λ

  hc = Φ λ                   Divide each side by Φ

   λ = hc/ Φ

   λ = (6.626 × 10⁻³⁴ × 2.998 × 10⁸)/(3.83 × 10⁻¹⁹)

   λ = 5.18 × 10⁻⁷ m     Convert to nanometres

   λ = 518 nm

The maximum wavelength that will cause an electron to move is 518 nm.

it is a good conductor

explanation:

both adhesion and cohesion are attractions.

they are different in that adhesion is the force of attraction between the molecules of two different substances, whereas cohesion is the force of attraction between molecules of the same substance.

possible examples include capillary action, in which the adhesion between water and glass causes the water to rise in a narrow tube against the force of gravity.

because of hydrogen bonding, water is extremely cohesive.

this causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on smooth surfaces.

hope this .