Answer:
Separate the reaction into half equations
Explanation:
When we want to balance redox equations, we must take cognizance of the fact that a specie was oxidized and another specie was reduced.
Hence we must identify the specie that was oxidized and the one that was reduced and then break up the whole redox reaction into oxidation and reduction half equations.
Given what we know, we can confirm that when an excited electron spontaneously emits a photon, the energy released is electromagnetic energy.
<h3>What is a Photon and what energy does it release when being emitted?</h3>
- A photon is a particle.
- This means that it is one of the smallest forms of matter that we can study.
- Photons form electromagnetic fields.
- Therefore, when being emitted by an electron, photons release electromagnetic energy.
Therefore, we can confirm that when an excited electron spontaneously emits a photon, the energy released is electromagnetic energy due to the properties of the photon being emitted.
To learn more about photons visit:
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Answer:
pH =3.8
Explanation:
Lets call the monoprotic weak acid HA, the dissociation equilibria in water will be:
HA + H₂O ⇄ H₃O⁺ + A⁻ with Ka = [ H₃O⁺] x [A⁻]/ [HA]
The pH is the negative log of the H₃O⁺ concentration, we know the equilibrium constant, Ka and the original acid concentration. So we will need to find the [H₃O⁺] to solve this question.
In order to do that lets set up the ICE table helper which accounts for the species at equilibrium:
HA H₃O⁺ A⁻
Initial, M 0.40 0 0
Change , M -x +x +x
Equilibrium, M 0.40 - x x x
Lets express these concentrations in terms of the equilibrium constant:
Ka = x² / (0.40 - x )
Now the equilibrium constant is so small ( very little dissociation of HA ) that is safe to approximate 0.40 - x to 0.40,
7.3 x 10⁻⁶ = x² / 0.40 ⇒ x = √( 7.3 x 10⁻⁶ x 0.40 ) = 1.71 x 10⁻³
[H₃O⁺] = 1.71 x 10⁻³
Indeed 1.71 x 10⁻³ is small compared to 0.40 (0.4 %). To be a good approximation our value should be less or equal to 5 %.
pH = - log ( 1.71 x 10⁻³ ) = 3.8
Note: when the aprroximation is greater than 5 % we will need to solve the resulting quadratic equation.
