Answer:
0.004548 M is the concentration of B at equilibrium at 500 K.
Explanation:
A(aq) ⇆ 2 B(aq)
Initially 3.00 M
At equilibrium 3.00 -x 2x
Equilibrium constant of the reaction at 500 K =
Concentration of A at 500 K at equilibrium , [A] = (3.00 -x )M
Concentration of B at 500 K at equilibrium,[B]= 2x
An expression of equilibrium constant is given as:
![K_c=\frac{[B]^2}{[A]}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BB%5D%5E2%7D%7B%5BA%5D%7D)
On solving for x:
x = 0.002274 M
[B] = 2 x = 2 × 0.002274 M = 0.004548 M
[A] = (3-x) = 3 M - 0.002274 M =2.997726 M
0.004548 M is the concentration of B at equilibrium.
Answer:
(B) 3
Explanation:
Citric acid has an acid dissociation constant (Ka) of 8.4 × 10⁻⁴. When it forms a buffer with its conjugate base (citrate), we can calculate the pH using the Henderson-Hasselbalch's equation.
![pH=pKa+log\frac{[base]}{[acid]}](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%5Cfrac%7B%5Bbase%5D%7D%7B%5Bacid%5D%7D)
The optimum range of pH is pKa ± 1. The pKa is -log Ka = -log (8.4 × 10⁻⁴) = 3.1. The buffer would be more effective for pH between 2.1 and 4.1, especially around 3.1. So the best choice is (B) 3.
The reaction equation is:
2HF(aq) + Ba(OH)₂(aq) → BaF₂(s) + H₂O (aq)
Writing the ionic form of this equation:
2H⁺ + 2F⁻ + Ba⁺² + 2OH⁻ → BaF₂ + H⁺ + OH⁻
The solubility of barium fluoride is 0.16 grams per 100 ml of water, which means that it is an insoluble compound. Moreover, spectator ions are those that remain unchanged before and after a reaction, so they "spectate" the reaction. In this case, the ions unchanged before and after the reaction are H⁺ and OH⁻.
