We are given the molar concentration of an aqueous solution of weak acid and the pH ofthe solution, and we are asked to determine the value of Ka for the acid.
The first step in solving any equilibrium problem is to write the equation for the equilibriumreaction. The ionization of benzoic acid can be written as seen in the attached image (1).
The equilibrium-constant expression is the equation number (2)
From the measured pH, we can calculate pH as seen in equation (3)
To determine the concentrations of the species involved in the equilibrium, we imagine that thesolution is initially 0.10 M in HCOOH molecules. We then consider the ionization of the acidinto H+ and HCOO-. For each HCOOH molecule that ionizes, one H+ ion and one HCOO- ionare produced in solution. Because the pH measurement indicates that [H+] = 1x 10^-4 M atequilibrium, we can construct the following table as seen in the equation number (4)
To find the value of Ka, please see equation (5):
We can now insert the equilibrium concentrations into the expression for Ka as seen in equation (6)
Therefore, 2.58x10^-4 M is the concentration of benzoic acid to have a pH of 4.0
- We cannot change protons of any element
- So the atomic number is 33
- The element is Arsenic(As)
Now here is 36 electrons so it's. tri cation.
Symbol

Answer:
Partial pressure of Ne = 1.43 atm
Explanation:
Step 1: Data given
Volume = 3.0 L
Number of moles He = 4 moles
Number of moles Ne = 2 moles
Number of moles Ar = 1 mol
Total pressure = 5 atm
Step 2: Calculate total moles
Total moles = 4 moles + 2 moles + 1 mol
Total moles = 7 moles
Step 3: Calculate the mol ratio
Mol ratio = moles / total mol
Mol ratio He = 4 moles / 7 moles = 0.571
Mol ratio Ne = 2 moles / 7 moles = 0.286
Mol ratio Ar = 1 mol / 7 moles = 0.143 moles
Ste p4: Calculate partial pressure
PArtial pressure = mol ratio * total pressure
Partial pressure of Ne = mol ratio Ne * total pressure
Partial pressure of Ne = 0.286 * 5 atm
Partial pressure of Ne = 1.43 atm