Calculate the value of kb for this base

Thread starter nysoprano
Start date Dec 20, 2004
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Base Value

In summary, the formula for calculating the value of kb for a base is: kb = [OH-][H+]/[B-], where [OH-] represents the concentration of hydroxide ions, [H+] represents the concentration of hydrogen ions, and [B-] represents the concentration of the base. The concentration of hydroxide ions and hydrogen ions can be determined by performing a titration experiment with a known volume of the base and a strong acid. Only weak bases should be used for calculating kb, as strong bases will completely dissociate in water. The units for kb depend on the units used for the concentration of hydroxide and hydrogen ions, but it is commonly expressed in mol/L. The value of kb

Dec 20, 2004

nysoprano

pH help??

This is the question i need help in:
A 0.200 M solution of a weak base in water has a pH=10.40. Calculate the value of kb for this base.

I know the answer but i need help on how to get that answer. Thanks

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Dec 20, 2004

Pyrrhus

Homework Helper

If its a weak base then it doesn't diassociates completely in OH ions, so you need to use the equilibrium solution.

Dec 21, 2004

Sirus

This may help: see post #5 here.

FAQ: Calculate the value of kb for this base

What is the formula for calculating the value of kb for a base?

The formula for calculating the value of kb for a base is: kb = [OH-][H+]/[B-], where [OH-] represents the concentration of hydroxide ions, [H+] represents the concentration of hydrogen ions, and [B-] represents the concentration of the base.

How do I determine the concentration of hydroxide ions and hydrogen ions?

The concentration of hydroxide ions and hydrogen ions can be determined by performing a titration experiment. In this experiment, a known volume of the base is titrated with a strong acid, and the amount of acid needed to neutralize the base is measured. This information can then be used to calculate the concentration of hydroxide and hydrogen ions.

Can I use any base to calculate the value of kb?

No, the base used for calculating kb should be a weak base. Strong bases will completely dissociate in water, making it difficult to accurately measure the concentration of hydroxide ions. Weak bases, on the other hand, only partially dissociate, allowing for more accurate calculations of kb.

What units are used for kb?

The units for kb will depend on the units used for the concentration of hydroxide and hydrogen ions. However, it is common to express kb in units of mol/L.

How do I interpret the value of kb?

The value of kb represents the strength of a weak base. A higher value of kb indicates a stronger base, while a lower value of kb indicates a weaker base. It is also important to note that the value of kb is temperature-dependent, so it should be measured at a specific temperature and compared to values measured at the same temperature.