The kinetic energy of emitted electrons when cesium is exposed to UV rays of frequency 1.80 * 10 ^15 is 3.054 x 10 ^- 19 J.
Explanation:
To calculate the kinetic energy of emitted electrons,
It is given that the frequency is 1.80* 10^15 Hz
We have,
KE = E – Eo = hv –hvo
Where, h = 6.626 x 10^ - 34 Js
Given frequency = 1.4 x 10 ^ 15 Hz
vo (Threshold frequency) for cesium = 9.39 x 10 ^ 14 Hz
Applying in equation,
we get
KE = 6.626 x 10^34 (1.4 x 10^15 - 9.39 x 10^14)
KE= 3.054 x 10^-19 J
[Note: Here, threshold frequency of Cesium is not provided. Apply the correct threshold frequency from the part A]
Answer:
The correct answer is 281.39 grams.
Explanation:
To arrive at this answer you must first keep in mind the basic equation:
<em>Q = m*Cp* ΔT</em>
Now, in order to calculate the necessary aluminum mass that absorbs 2138 J when passing from 14.83 to 23.31 ° C you must "clear" <em>m</em> of the previous equation.
This means, leave only the mass on one side of the equation, and "pass" <em>Cp</em> and <em>ΔT</em> to the other side dividing <em>Q</em>. This would look like this:
m= Q/ (Cp*ΔT)
Then, <u>you need the value of specific heat of aluminum</u> in the correct units, that is J / g ° C, the approximate value is 0.896.
ΔT is calculated by doing the mathematical operation:
23.31 °C - 14.83 °C = 8.48 °C
<em>
Finally, the values of: Q (data provided in joules), Cp (J / g ° C) and ΔT (calculated in ° C) are replaced in the last equation and the mass (in grams) is calculated resulting in 281.39 grams.</em>
Answer:
Absorbed
Released
Released
Explanation:
The formation of a cation is an endothermic process because energy must be absorbed in order to remove an electron from an atom.
Similarly, energy is evolved when an electron is added to an atom to form a negative ion.
The formation of an ionic compound is an exothermic process. Since ionic compounds are more stable than the individual ions separated by a distance, the excess energy of the isolated ions is evolved when the ionic compound is formed.
