1st one is Science and the 2nd one is Bias
During the Physical changes
The given question is incomplete. The complete question is as follows.
Which of the following best helps explain why an increase in temperature increases the rate of a chemical reaction?
(a) at higher temperatures, high-energy collisions happen less frequently.
(b) at low temperatures, low-energy collisions happen more frequently.
(c) at higher temperatures, less-energy collisions happen less frequently.
(d) at higher temperatures, high-energy collisions happen more frequently
Explanation:
When we increase the temperature of a chemical reaction then molecules of the reactant species tend to gain kinetic energy. As a result, they come into motion which leads to more number of collisions within the molecules.
Therefore, chemical reaction will take less amount of time in order to reach its end point. This means that there will occur an increase in rate of reaction.
Thus, we can conclude that the statement at higher temperatures, high-energy collisions happen more frequently, best explains why an increase in temperature increases the rate of a chemical reaction.
The answer is Ka = 1.00x10^-10.
Solution:
When given the pH value of the solution equal to 11, we can compute for pOH as
pOH = 14 - pH = 14 - 11.00 = 3.00
We solve for the concentration of OH- using the equation
[OH-] = 10^-pOH = 10^-3 = x
Considering the sodium salt NaA in water, we have the equation
NaA → Na+ + A-
hence, [A-] = 0.0100 M
Since HA is a weak acid, then A- must be the conjugate base and we can set up an ICE table for the reaction
A- + H2O ⇌ HA + OH-
Initial 0.0100 0 0
Change -x +x +x
Equilibrium 0.0100-x x x
We can now calculate the Kb for A-:
Kb = [HA][OH-] / [A-]
= x<span>²</span> / 0.0100-x
Approximating that x is negligible compared to 0.0100 simplifies the equation to
Kb = (10^-3)² / 0.0100 = 0.000100 = 1.00x10^-4
We can finally calculate the Ka for HA from the Kb, since we know that Kw = Ka*Kb = 1.0 x 10^-14:
Ka = Kw / Kb
= 1.00x10^-14 / 1.00x10^-4
= 1.00x10^-10
