Answer:
Explanation:
Hello there!
In this case, when considering weak acids which have an associated percent dissociation, we first need to set up the ionization reaction and the equilibrium expression:
![HA\rightleftharpoons H^++A^-\\\\Ka=\frac{[H^+][A^-]}{[HA]}](https://tex.z-dn.net/?f=HA%5Crightleftharpoons%20H%5E%2B%2BA%5E-%5C%5C%5C%5CKa%3D%5Cfrac%7B%5BH%5E%2B%5D%5BA%5E-%5D%7D%7B%5BHA%5D%7D)
Now, by introducing x as the reaction extent which also represents the concentration of both H+ and A-, we have:
![Ka=\frac{x^2}{[HA]_0-x} =10^{-4.74}=1.82x10^{-5}](https://tex.z-dn.net/?f=Ka%3D%5Cfrac%7Bx%5E2%7D%7B%5BHA%5D_0-x%7D%20%3D10%5E%7B-4.74%7D%3D1.82x10%5E%7B-5%7D)
Thus, it is possible to find x given the pH as shown below:
So that we can calculate the initial concentration of the acid:
![\frac{(1.82x10^{-5})^2}{[HA]_0-1.82x10^{-5}} =1.82x10^{-5}\\\\\frac{1.82x10^{-5}}{[HA]_0-1.82x10^{-5}} =1\\\\](https://tex.z-dn.net/?f=%5Cfrac%7B%281.82x10%5E%7B-5%7D%29%5E2%7D%7B%5BHA%5D_0-1.82x10%5E%7B-5%7D%7D%20%3D1.82x10%5E%7B-5%7D%5C%5C%5C%5C%5Cfrac%7B1.82x10%5E%7B-5%7D%7D%7B%5BHA%5D_0-1.82x10%5E%7B-5%7D%7D%20%3D1%5C%5C%5C%5C)
![[HA]_0=3.64x10^{-5}M](https://tex.z-dn.net/?f=%5BHA%5D_0%3D3.64x10%5E%7B-5%7DM)
Therefore, the percent dissociation turns out to be:
![\% diss=\frac{x}{[HA]_0}*100\% \\\\\% diss=\frac{1.82x10^{-5}M}{3.64x10^{-5}M}*100\% \\\\\% diss = 50\%](https://tex.z-dn.net/?f=%5C%25%20diss%3D%5Cfrac%7Bx%7D%7B%5BHA%5D_0%7D%2A100%5C%25%20%5C%5C%5C%5C%5C%25%20diss%3D%5Cfrac%7B1.82x10%5E%7B-5%7DM%7D%7B3.64x10%5E%7B-5%7DM%7D%2A100%5C%25%20%5C%5C%5C%5C%5C%25%20diss%20%3D%2050%5C%25)
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15. D is correct, exothermic reactions release heat
I am not sure about 16
Answer: 83.11 torr
Explanation:
According to Dalton's Law of partial pressure, the total pressure of a mixture of gases is the sum of the pressure of each individual gas.
i.e Ptotal = P1 + P2 + P3 + .......
In this case,
Ptotal = 384 torr
P1 = 289 torr
P2 = 11.89 torr
P3 = ? (let the partial pressure of the remaining gas be Z)
Ptotal = P1 + P2 + Z
384 torr = 289 torr + 11.89 torr + Z
384 torr = 300.89 torr + Z
Z = 384 torr - 300.89 torr
Z = 83.11 torr
Thus, the partial pressure of the remaining gas is 83.11 torr.
Answer:
The chemical reaction in which solid calcium oxide is treated liquid water is an example of Synthesis reaction. Hence, the answer is (D) Synthesis.
Explanation:
The formula of Calcium Oxide is CaO.
The formula of liquid water is H₂O.
Calcium Oxide reacts with water and forms Calcium Hydroxide. The Chemical equation is shown below.
CaO + H₂O --> Ca(OH)₂.
This is a Synthesis reaction because Ca(OH)₂ is synthesized by using Calcium Oxide and water.
The product of this reaction is calcium hydroxide, also known as slaked lime.
Thus, when calcium oxide reacts with water, slaked lime is produced.
Calcium oxide is also known as lime and is most commonly used for many purposes. It can be used for pH correction of water or for its disinfection (with excess lime).
