Phenol is a weak acid. We take 3.7 grams of phenol and dissolve it in 65 ml of water. To that water we add 40 ml of a 0.52 M solution of NaOH.
You will need to look up the Ka value for Phenol
a. What is the pH when the phenol is dissolved in the 65 ml of water ?
b. Once the base is added, what is the resulting pH ?
c. What is the total volume of base needed to reach the equivalence point ?
a. Call phenol HP.
mols HP = grams/molar mass = approx 0.04 but you need a better number than that. Then M = mols/L = 0.04/0.065 = approx 0.6
.....HP ==> H^+ + P^-
I...0.6.....0......0
C....-x.....x......x
E...0.6-x...x......x
Substitute the E line into Ka for phenol and solve for x = (H^+), then convert to pH.
b.
HP + NaOH ==> NaP + H2O
You have mols HP initially.
Caculate mols NaOH added.
One will be in excess; probably HP but you need to confirm that.
Calculate how much of the excess reagent is present. That many mols/total volume in L will give you the M of the excess reagent. If HP is the excess then redo as in part a to calculate pH.
c. mL HP x M HP = mLNaOH x M NaOH.
Substitute and solve for mL NaOH
To answer these questions, we need to understand the concept of acid dissociation constant (Ka) and how it relates to the pH of a solution. Additionally, we'll need the molar mass of phenol (C6H6O) and the volume of base needed to reach the equivalence point.
a. To find the pH when phenol is dissolved in water, we need to calculate the concentration of phenol (C6H6O) in the solution and use the Ka value of phenol. The Ka value for phenol can be found by looking it up in a reliable source, such as a chemistry textbook or an online database.
b. Once the base (NaOH) is added, we need to consider the reaction between phenol (acid) and NaOH (base). This reaction will produce water and a salt. We'll need to calculate the concentration of the resulting species in order to find the resulting pH.
c. To determine the total volume of base needed to reach the equivalence point, we need to understand the concept of titration. The equivalence point is the point at which the moles of acid are equal to the moles of base added. By using stoichiometry, we can calculate the volume (in mL) of base needed to neutralize the phenol.
Please provide the Ka value for phenol, and we can proceed with the calculations.