Ionisation of water and pH Flashcards
What is the self-ionisation of water?
Water is a weak electrolyte that undergoes auto-ionisation to a very small extent.
What does the equilibrium of water ionisation strongly favour?
The reactants.
What is the equilibrium constant for the ionisation of water at 25°C?
1.0 x 10^-14.
What is the concentration of hydrogen ions in mol L^-1 in pure water?
1.0 x 10^-7.
In acidic solutions, how does the concentration of H+ compare to OH-?
H+ is greater than OH-.
In basic solutions, how does the concentration of OH- compare to H+?
OH- is greater than H+.
What is the formula for the ionisation constant of water?
Kw = [H3O+][OH-].
What is the pH of pure water or a neutral solution?
7.0.
How is acidity commonly indicated in solutions?
Using the pH scale.
What does a decrease in pH indicate about a solution?
Increased acidity.
What is the relationship between pH and hydrogen ion concentration?
A change of one pH unit represents a tenfold change in the hydrogen ion concentration.
What instrument can be used to obtain a precise pH measurement?
A pH meter.
What is the pOH of a solution with [OH-] = 0.080 M?
1.10.
Calculate the pH given pOH = 1.10.
12.9.
What happens to Kw at temperatures above 25°C?
Kw must be greater than 1 x 10^-14.
What is the pH of pure water at 40°C?
< 7 (specifically 6.77).
In the ionisation of water, what ions are produced?
- H3O+ * OH-
Fill in the blank: The pH of a basic solution is ______.
> 7.
Fill in the blank: The pH of an acidic solution is ______.
< 7.
True or False: The concentration of the solvent is included in the ionisation constant expression.
False.
What is the value of Kw at 25°C?
1.0 x 10^-14.
What is the concentration of H+ ions in a 0.008 mol L^-1 H2SO4 solution?
0.016 M.
Calculate the pOH from a pH of 1.80.
12.2.
