Answer:
the oxidation number of hydrogen is +2, while oxygen is -2
Answer:
b
Explanation:
As the coin is rubbed, the particles in the coin vibrate (presenting kinetic energy in the particles i.e. heat). The heat is transferred as thermal energy.
I’m not sure but I hope yu get the right answer sorry
Answer:
5.42
Explanation:
Step 1: Consider the dissociation of NH₄Br
NH₄Br(aq) ⇒ NH₄⁺(aq) + Br⁻(aq)
Br⁻ is the conjugate base of HBr, a strong acid, so it doesn´t react with water. NH₄⁺ is the conjugate acid of NH₃, so it does react with water.
Step 2: Consider the acid reaction of NH₄⁺
NH₄⁺(aq) + H₂O(l) ⇄ NH₃(aq) + H₃O⁺(aq)
Step 3: calculate the acid dissociation constant for NH₄⁺
We will use the following expression.
![K_a \times K_b = K_w\\K_a = \frac{K_w}{K_b} = \frac{1.00 \times 10^{-14} }{1.76 \times 10^{-5}} = 5.68 \times 10^{-10}](https://tex.z-dn.net/?f=K_a%20%5Ctimes%20K_b%20%3D%20K_w%5C%5CK_a%20%3D%20%5Cfrac%7BK_w%7D%7BK_b%7D%20%3D%20%5Cfrac%7B1.00%20%5Ctimes%2010%5E%7B-14%7D%20%7D%7B1.76%20%5Ctimes%2010%5E%7B-5%7D%7D%20%3D%205.68%20%5Ctimes%2010%5E%7B-10%7D)
Step 4: Calculate the concentration of H₃O⁺
We will use the following expression.
![[H_3O^{+} ]= \sqrt{K_a \times C_a } = \sqrt{5.68 \times 10^{-10} \times 0.0255 } = 3.81 \times 10^{-6}M](https://tex.z-dn.net/?f=%5BH_3O%5E%7B%2B%7D%20%5D%3D%20%5Csqrt%7BK_a%20%5Ctimes%20C_a%20%7D%20%3D%20%5Csqrt%7B5.68%20%5Ctimes%2010%5E%7B-10%7D%20%5Ctimes%200.0255%20%7D%20%3D%20%203.81%20%5Ctimes%2010%5E%7B-6%7DM)
Step 5: Calculate the pH
We will use the following expression.
![pH = -log [H_3O^{+} ] = -log (3.81 \times 10^{-6}) = 5.42](https://tex.z-dn.net/?f=pH%20%3D%20-log%20%5BH_3O%5E%7B%2B%7D%20%5D%20%3D%20-log%20%283.81%20%5Ctimes%2010%5E%7B-6%7D%29%20%3D%205.42)