136 THE THEORY OF IONIZATIONtion the pH value of the solution is determined. Three of the
most commonly used indicators are included in the following table.
Indicator Acid color pH range of color transition Basic color
methyl orange red 3.2-4.4 yellow
litmus red 4.5-8.3 blue
phenolphthalein colorless 8.3-10 red
PROBLEMS- From the per cent of ionization of hydrocyanic acid in 0.1 N
solution find the value of the ionization constant of that acid. - Calculate the H+ ion concentration in a solution 0.1 N in
HCN and O.liV in KCN. What is the pH value of this solution? - Calculate the pH value of 0.01 N acetic acid. What color
would this solution impart to methyl orange? - Calculate the pH value of 0.01 N HC 2 H 3 O 2 containing
0.1 F.W. of NaC 2 H 3 O 2 per liter. What color would this solution
impart to methyl orange?