Sodium benzoate (c6h5coona), the sodium salt of the weak acid benzoic acid, is used as a food preservative. a solution is prepared by dissolving 0.100 mol of sodium benzoate in enough pure water to produce 1.00 l of solution. if the pka for benzoic acid is 4.20, calculate the ph of the sodium benzoate solution.

8.6

Explanation:

Using the expression :

Where, is the dissociation constant of water.

At ,

Thus, for benzoic acid , pKa = 4.20

Thus,

for Sodium benzoate can be calculated as:

The benzoate ion will dissociate as:-

expression is:-

Given that:-

Moles = 0.100 moles

Volume = 1.00 L

Thus, Concentration = 0.100/ 1.00 M = 0.1 M

Considering the ICE table in the image below.

So,

Solving for x, we get that,

Thus,

Also,

Also, pH + pOH = 14  

So, pH = 14 - 5.4 = 8.6

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )