How does kb relate to base strength

Here are definitions of each term, simple formulas used to calculate them, and an explanation of how they differ from one another. So, pH is the negative log of hydrogen ion concentration, while pKa is the negative log of the Ka value.

In this case, it refers to the equilibrium constant. Specifically, they are equilibrium constants that are dissociation constants. Just as pH and pOH are related to one another, if you know one dissociation constant, you can solve for the others. In other words, the equilibrium constants indicate acid and base strength and describe the level of ionization of an acid or a base. We can use the relative strengths of acids and bases to predict the direction of an acid—base reaction by following a single rule: an acid—base equilibrium always favors the side with the weaker acid and base, as indicated by these arrows:.

Hence the ionization equilibrium lies virtually all the way to the right, as represented by a single arrow:. In contrast, acetic acid is a weak acid, and water is a weak base. Similarly, in the reaction of ammonia with water, the hydroxide ion is a strong base, and ammonia is a weak base, whereas the ammonium ion is a stronger acid than water.

Hence this equilibrium also lies to the left:. Reserve Spot. Ka and pKa Acids are classified as either strong or weak, based on their ionization in water.

A strong acid is an acid which is completely ionized in an aqueous solution. A weak acid is an acid that ionizes only slightly in an aqueous solution. The ionization for a general weak acid, HA, can be written as follows:. Because the acid is weak, an equilibrium expression can be written. An acid ionization constant K a is the equilibrium constant for the ionization of an acid.

The acid ionization represents the fraction of the original acid that has been ionized in solution. Therefore, the numerical value of K a is a reflection of the strength of the acid. Weak acids with relatively higher K a values are stronger than acids with relatively lower K a values. For this reason, K a values are generally reported for weak acids only.

The logarithmic constant pKa is equal to -log10 Ka. The larger the value of pKa, the smaller the extent of dissociation. A weak acid has a pKa value in the approximate range of -2 to 12 in water.

Acids with a pKa value of less than about -2 are said to be strong acids. Kb and pKb As with acids, bases can either be strong or weak, depending on their extent of ionization. A strong base is a base, which ionizes completely in an aqueous solution. A weak base is a base that ionizes only slightly in an aqueous solution. For strong acids, i.

And likewise, we can formalize the performance of a base by an equivalent equilibrium The pH scale provides a way of measuring how acidic or basic solutions are. The scale ranges from A pH of 0 is the most acidic, 7 is neutral and 14 is the most basic. Here is a video of a lab which looks at a number of different solutions and measures their pH levels using a pH meter and an indicator.

Key Questions What are pKa and pKb in acids and bases? We convert these exponential numbers into a normal range by taking their negative logarithm.

The operator "p" means "take the negative logarithm of". Bases When you dissolve a base in water, it reacts with the water in an equilibrium reaction. Ernest Z. What are Ka and Kb in acids and bases? Answer: These are measures of acidity and basicity Explanation: And acid in aqueous solution is conceived to undergo a protonolysis reaction Confused yet?

What is pH in acids and bases? What are pKa and pKb in acids and bases? How do you calculate the pH of a buffer solution? How can I calculate the pH of a weak acid with an example?