Answer:

Explanation:
The activation energy represents the energy barrier that reagents must pass to transform into products (or products to transform into reagents in a reverse reaction)
For any reaction, the change in enthalpy is related to the activation energy by the equation

So, the activation energy for the reverse reaction is

Answer:
Pb(NO3)2 – Lead(II) nitrate sourceaà
Other names: Lead nitrate source Plumbous nitrate source Lead dinitrate source
Appearance: White colourless crystals asource:White or colourless crystals source.
H2O – Water, oxidane source
Other names: Water (H2O) source: Hydrogen hydroxide (HH or HOH) source: Hydrogen oxide source
Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas source.
Answer:
pKa of the acid HA with given equilibrium concentrations is 6.8
Explanation:
The dissolution reaction is:
HA ⇔ H⁺ + A⁻
So at equilibrium, Ka is calculated as below
Ka = [H⁺] x [A⁻] / [HA] = 2.00 x 10⁻⁴ x 2.00 x 10⁻⁴ / 0.260
= 15.38 x 10⁻⁸
Hence, by definition,
pKa = -log(Ka) = - log(15.38 x 10⁻⁸) = 6.813
The first element discovered through synthesis was technetium<span>—its discovery being definitely confirmed in 1936. Hope that helps.</span>