To clean a clogged drain, 26g of sodium hydroxide is added to water to make 150ml of solution. What are the pH and pOH values for the solution?
How many mols NaOH do you have? That's grams/molar mass = ?
M NaOH = mols/L soln.
M NaOH = (OH^-)
pH and pOH as in the problem above.
To find the pH and pOH values of the solution, you need to determine the concentration of hydroxide ions (OH-) or hydrogen ions (H+). The pH value represents the concentration of hydrogen ions, while the pOH value represents the concentration of hydroxide ions.
We can start by calculating the concentration of the sodium hydroxide solution using the given information.
Step 1: Convert grams to moles of sodium hydroxide
To convert grams to moles, we need to know the molar mass of sodium hydroxide (NaOH), which is 40 g/mol (22.99 g/mol for sodium + 16.00 g/mol for oxygen + 1.01 g/mol for hydrogen).
Number of Moles = Mass / Molar Mass
Number of Moles = 26 g / 40 g/mol
Number of Moles ≈ 0.65 mol
Step 2: Calculate the molarity of the solution
Molarity (M) = Number of Moles / Volume (L)
Given that the volume is 150 ml (or 0.150 L),
Molarity = 0.65 mol / 0.150 L
Molarity ≈ 4.33 M
Now that we know the molarity of the solution, we can find the concentration of hydroxide ions (OH-), as sodium hydroxide fully dissociates in water, yielding one hydroxide ion for every sodium hydroxide molecule.
Therefore, the concentration of hydroxide ions (OH-) is also approximately 4.33 M.
Step 3: Calculate the pOH value
Since pOH is the negative logarithm (base 10) of the hydroxide ion concentration (OH-), we can use the formula:
pOH = -log[OH-]
pOH = -log(4.33)
pOH ≈ 0.363
Step 4: Calculate the pH value
The pH is related to the pOH using the formula:
pH + pOH = 14
Using this relationship, we can find the pH value:
pH + 0.363 = 14
pH ≈ 13.64
Therefore, the pH value of the sodium hydroxide solution is approximately 13.64, and the pOH value is approximately 0.363.