# Chemistry - Is LiOH a weaker base than NaOH?

## Solution 1:

In Proton Affinities of the Alkali Hydroxides J. Am. Chem. Soc., 1969, 91, pp 2810–2811, it is shown that gas phase affinities in $$\pu{kcal/mol}$$ are:

• $$\ce{LiOH}$$: 240.7
• $$\ce{NaOH}$$: 247.6
• $$\ce{KOH}$$: 262.6
• $$\ce{CsOH}$$: 269.2

So, yes, $$\ce{LiOH}$$ is weaker, at least in the gas phase.

In aqueous solution, ACIDITY FUNCTIONS FOR STRONGLY BASIC SOLUTIONS Chemical Reviews volume 66, pages 119-131:

the order of basicity for the same molarity of aqueous solution, $$\ce{LiOH < NaOH < KOH}$$.

For example, for a $$\pu{1M}$$ solution, the acidity function (H) is:

• $$\ce{LiOH}$$: 13.48
• $$\ce{NaOH}$$: 14.01, 14.16 (two different measurement techniques)
• $$\ce{KOH}$$: 14.17

So in both the gas and aqueous phases, $$\ce{LiOH}$$ is a weaker base than $$\ce{NaOH}$$.

## Solution 2:

The reference

  Acids and Bases (Essential Chemistry)
Kristi Lew
Publisher: Chelsea House Publications; Library Binding edition (December 1, 2008)
Language: English
ISBN-10: 0791097838
ISBN-13: 978-0791097830


from page 42

I clipped the image from Goggle books. So far as I know the pKb values for LiOH, NaOH and KOH do not have a primary source listed.