What is the pH and pOH of a solution made by adding water to 15 grams of hydroiodic acid until the
volume of the solution is 2500 mL? (hint: you must calculate the molarity first)
15g*(1 mole/36.46g)=moles
(moles/2.5L)= ???
-log[????]=pH
14-pH=pOH
Answers should contain two numbers after the decimal.
Anonymous oops.
The molar mass HI is not 36.46. It is 126.9 + 1 = 127.9
To find the pH and pOH of the solution, we need to calculate the molarity of the hydroiodic acid.
Step 1: Calculate the number of moles of hydroiodic acid.
To do this, we need the molar mass of hydroiodic acid (HI), which is approximately 127.9 g/mol.
Number of moles = mass / molar mass
Number of moles = 15 g / 127.9 g/mol
Number of moles ≈ 0.117 moles
Step 2: Calculate the molarity of the hydroiodic acid solution.
Molarity (M) = moles / volume (in liters)
The volume of the solution is given as 2500 mL, which is equal to 2.5 L.
Molarity = 0.117 moles / 2.5 L
Molarity ≈ 0.047 M
Now that we have the molarity of the hydroiodic acid solution, we can find the pH and pOH using the following equations:
pH = -log[H+]
pOH = -log[OH-]
Step 3: Calculate the concentration of H+ ions.
Since hydroiodic acid is a strong acid and completely dissociates in water, the concentration of H+ ions is equal to the molarity of the acid solution.
[H+] = 0.047 M
Step 4: Calculate the pH.
pH = -log(0.047)
pH ≈ 1.33
Step 5: Calculate the pOH.
Since this is an acid solution, there are no OH- ions present, so pOH = 0.
Therefore, the pH of the solution is approximately 1.33, and the pOH is 0.
To find the pH and pOH of the solution, we need to calculate the molarity of hydroiodic acid first. Here's how you can do that:
Step 1: Convert the mass of hydroiodic acid to moles.
The molar mass of hydroiodic acid (HI) is approximately 127.91 g/mol. So, first, we need to calculate the number of moles of HI:
moles of HI = mass of HI / molar mass of HI
= 15 g / 127.91 g/mol
Step 2: Convert the volume of the solution to liters.
The volume of the solution is given as 2500 mL. To convert it to liters, divide by 1000:
volume of solution = 2500 mL / 1000
= 2.5 L
Step 3: Calculate the molarity of the solution.
Now that we have the number of moles of HI and the volume of the solution in liters, we can calculate the molarity:
molarity (M) = moles of HI / volume of solution (in liters)
= moles of HI / 2.5 L
Now that we have the molarity, we can proceed to find the pH and pOH of the solution.
Step 4: Calculate the pH and pOH.
The pH and pOH of a solution can be calculated using the following formulas:
pH = -log[H+]
pOH = -log[OH-]
Since hydroiodic acid is a strong acid, it dissociates completely in water, yielding H+ ions. Therefore, the concentration of H+ ions is equal to the molarity.
Using the molarity of the hydroiodic acid, we can now calculate the pH and pOH:
pH = -log[molarity of H+]
pOH = 14 - pH
I hope this step-by-step explanation helps you calculate the pH and pOH of the solution.