The acid dissociation constant is defined as Ka = [H+][A-]/[HA] where [H+], [A-] and [HA] are the concentrations of protons, conjugate base, and acid in solution respectively. Assuming this is a weak acid as the pH is quite high for a 1.35 M solution, we can assume that the change in [HA] is negligible and therefore [HA] = 1.35 M.
To calculate [H+] we can use the relationship pH = -log[H+], rearranging to give: [H+] = 10^(-pH) = 10^(-2.93) = 1.17 x 10^(-3).
Since the acid is relatively concentrated we can assume therefore that [H+] = [A-] as for each proton dissociated, a conjugate base is formed.
Therefore, we can calculate Ka as:
Ka = [H+]^2/[HA] = (1.17 x 10^-3 M)^2/1.35 = 1.01 x 10^-6 M
The question is incomplete. The complete question is stated below:
Two point charges are held at the corners of a rectangle as shown in the figure. The lengths of sides of the rectangle are 0.050 m and 0.150 m. Assume that the electric potential is defined to be zero at infinity.
a. Determine the electric potential at corner A.
b. What is the electric potential energy of a +3 µC charge placed at corner A?
Answer / Explanation:
a )V(A) = 1 / 4πe° ( - 5 5x10∧6C / 0.150m + 2x10∧6C / 0.050m )
The answer to the equation above is : = +6.0x10∧4 j/c
b) U(A) = qV(A)= (3.0x10∧6C) (6.0x10∧4 . j/c) =
The answer to the equation above is : =0.18 J
Explanation:
Where V(A) is equivalent to the electric potential
U(A) is equivalent to the electric potential energy
Answer:
0.125
Explanation:
im not sure but if you get the grams then divide by the sufficance of xy
Answer:
A chemical change
Explanation:
The marshmallow turning brown and bubbling implies that a chemical change has taken place.
For chemical changes to occur, we observe any of the following:
- a new kind of matter is formed.
- it is always accompanied by energy changes
- the process is not easily reversible
- it involves a change in mass
- requires considerable amount of energy.
ii. Two signs that shows a chemical change has taken place is that:
- bubbles are being formed as it is roasted and it implies that new substances have been formed.
- also, significant amount of heat energy is supplied for the roasting.
