Question #0984e
1 Answer
!! LONG ANSWER !!
Here's how you'd go about solving this one.
You're dealing with a reaction between acetic acid, a weak acid, and sodium hydroxide, a strong base.
Start with the balanced chemical equation for this neutralization reaction. Because sodium hydroxide is a strong base, it will dissociate completely in aqueous solution, so I'll write the net ionic equation
Notice the
If you have equal number of moles that react, both compounds will be completely consumed by the reaction. If you have more moles of acetic acid than of sodium hydroxide, all the base will be consumed and you'll be left with excess acetic acid.
Likewise, if you have more moles of sodium hydroxide, you'll be left with excess base.
Use the molarities and volumes of the two solutions to determine how many moles of each you have
and
So, you have equal numbers of moles of each compound. This means that the acetic acid and the sodium hydroxide will be consumed, and that you'll produce 0.1000 moles of acetate anions - this is because of the
Here's where it gets a little tricky. The acetate anion will react with water to reform some of the acid and produce hydroxide anions,
The molarity of the acetate anion will be - don't forget to use the total volume of the solution
Use an ICE table to determine the concentration of hydroxide anions
I..........0.2500..............................................0..........................0
C............(-x)................................................(+x).......................(+x)
E.........0.2500-x............................................x..........................x
Because the acetate anion acts as a base, you'll have to use the base dissociation constant,
This will get you
Because
The molarity of the hydroxide ions will be
The pOH of the solution will be
Therefore, the pH of the solution will be