00:01
For this question, we have a buffer, so we'll be using the henderson -hasselbalch equation, where ph equals pca plus the log of, we can use moles base over moles acid, or we can use concentration base over concentration acid.
00:21
It's going to be easier in this case to use moles.
00:25
So the ph that we want is going to be 4 .3.
00:30
The pca for benzoic acid is going to be the negative log of its ka value, which is 6 .3 times 10 to the negative 5.
00:47
And then it'll be plus the log of the moles of base.
00:53
So we want to know the mass of sodium benzate.
00:57
So let's calculate the moles of sodium benzate divided by the moles of benzodiaic acid.
01:05
Well we have 160 milliliters, which is 0 .160 liters, multiplied by its concentration of 0 .16 molar...