We assume that we have Ka= 4.2x10^-13 (missing in the question)
and when we have this equation:
H2PO4 (-) → H+ + HPO4-
and form the Ka equation we can get [H+]:
Ka= [H+] [HPO4-] / [H2PO4] and we have Ka= 4.2x10^-13 & [H2PO4-] = 0.55m
by substitution:
4.2x10^-13 = (z)(z)/ 0.55
z^2 = 2.31x 10^-13
z= 4.81x10^-7
∴[H+] = 4.81x10^-7
when PH equation is:
PH= -㏒[H+]
= -㏒(4.81x10^-7) = 6.32
Answer:
the answer is A
I made a chart for AP chem if you want to refer to it.
Acid Sorry if I am wrong but I am pretty positive it’s acid
7. 1,2,2,2
8. 4,3,1
9. 1,4,1,2
10. 3,4,1,4
Answer:
The frequency of photon is 0.75×10¹⁵ s⁻¹.
Explanation:
Given data:
Energy of photon = 5×10⁻¹⁹ J
Frequency of photon = ?
Solution:
Formula;
E = hf
h = planck's constant = 6.63×10⁻³⁴ Js
5×10⁻¹⁹ J = 6.63×10⁻³⁴ Js ×f
f = 5×10⁻¹⁹ J / 6.63×10⁻³⁴ Js
f = 0.75×10¹⁵ s⁻¹
The frequency of photon is 0.75×10¹⁵ s⁻¹.
