00:01
To calculate the ph of this buffer solution, we'll use the henderson -hassel -baltz equation, where ph will be equal to the p -k -a of the weak acid.
00:10
The k -a is provided at 4 .0 times 10 to the negative 8, so p -k -a can be calculated by taking the negative log of this k -a value.
00:25
We're then going to add on the lock of, it could be moles base, over -moles acid, or mol, of the base over molarity of the acid.
00:36
For this problem it's going to be easier to use a mole ratio.
00:41
So how many moles of the weak base do we start with before adding the hcl? we have 0 .155 molar in a 500 mill liter buffer solution.
00:56
So if we take our 500 mil liters and convert it to liters and multiply it by the concentration, concentration of the conjugate base, clo minus, at 0 .155, moles per liter.
01:12
The liters will cancel, and this will give us moles of the weak base we are starting with before adding the acid.
01:22
When we add the acid, the acid represented as h -3 -0 -plus, will react with the base, c -l -o - minus, and produce h -3 -0...