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magma_saber
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Homework Statement
How do i get the Ka of weak base indicators such as bromophenol blue, methly red, bromothymol blue, and phenolophalein? I found the pKa values online but i couldn't find their Ka values.
magma_saber said:how do you know is an acid or base is strong? I know that strong acids and bases completely dissociates, but how would i know if it completely dissociates?
For weak acids you can find the pH by taking the negative log of the square root of Ka times the initial concentration of the acid.
But if its a strong acid, you only have to take the negative log of the initial concentration. i.e. 6 M HCl, the pH is -log(6.0). What is the pH of 3 M HNO3?
magma_saber said:I found these in wikipedia. I'm guessing that these are the only one's I'm going to have to remember.
Potassium hydroxide (KOH)
Caesium hydroxide (CsOH)
Sodium hydroxide (NaOH)
Lithium hydroxide (LiOH)
Rubidium hydroxide (RbOH)
Strontium hydroxide (Sr(OH)2)
Calcium hydroxide (Ca(OH)2)
Barium hydroxide (Ba(OH)2)
Hydroiodic acid HI
Hydrobromic acid HBr
Hydrochloric acid HCl
Perchloric acid HClO4
Sulfuric acid H2SO4 (Ka1/first dissociation only)
Nitric acid HNO3
Hydronium ion H3O+ or H+
So other than these compounds, almost all the rest are all weak acids or bases right?
also the pH of 3 M of HNO3 is -0.48 right? and the pOH is 14.48? i only need the approximations.
The Ka of a weak acid indicator is a measure of its acidity and is also known as the acid dissociation constant. It tells us how much the indicator will dissociate into its constituent ions in a solution.
The Ka of a weak acid indicator can be determined experimentally by measuring the concentration of the dissociated ions in a solution of known concentration of the indicator. It can also be calculated using the equilibrium constant expression for the dissociation reaction.
The Ka value of a weak acid indicator determines the pH at which it will change color. Indicators with higher Ka values will change color at lower pH values, while those with lower Ka values will change color at higher pH values.
The Ka value is directly related to the strength of a weak acid indicator. A higher Ka value indicates a stronger acid and a lower Ka value indicates a weaker acid.
No, the Ka value of a weak acid indicator is a constant for a given temperature and pressure. However, it may vary slightly due to changes in these factors or impurities in the indicator solution.