You need to prepare 100.0 mL of a pH 4.00 buffer solution using 0.100 M benzoic acid (p K a = 4.20 ) and 0.200 M sodium benzoate. How many milliliters of each solution should be mixed to prepare this buffer?

Answer : The volume of sodium benzoate and benzoic acid  solution mixed to prepare this buffer should be, 29.0 mL and 71 mL respectively.

Explanation :

Let the volume of sodium benzoate (salt) be, x

So, the volume of benzoic acid  (acid) will be, (100 - x)

Using Henderson Hesselbach equation :

Now put all the given values in this expression, we get:

x = 29.0

The volume of sodium benzoate = x = 29.0 mL

The volume of benzoic acid  (acid) = (100 - x) = (100 - 29.0) = 71 mL

Thus, the volume of sodium benzoate and benzoic acid  solution mixed to prepare this buffer should be, 29.0 mL and 71 mL respectively.

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.