Search for:. Strength of Acids Strong Acids In water, strong acids completely dissociate into free protons and their conjugate base. Learning Objectives Calculate pH for solutions of strong acids.
Key Takeaways Key Points Strong acids can catalyze chemical reactions. Strong acids are defined by their pKa. The acid must be stronger in aqueous solution than a hydronium ion, so its pKa must be lower than that of a hydronium ion.
Strong acids can be organic or inorganic. Strong acids must be handled carefully because they can cause severe chemical burns. Strong acids are essential for catalyzing some reactions, including the synthesis and hydrolysis of carbonyl compounds.
Key Terms carbonyl : a divalent functional group -CO- , characteristic of aldehydes, ketones, carboxylic acids, amides, carboxylic acid anhydrides, carbonyl halides, esters, and others. Weak Acids A weak acid only partially dissociates in solution. Learning Objectives Solve acid-base equilibrium problems for weak acids. Key Takeaways Key Points The dissociation of weak acids, which are the most popular type of acid, can be calculated mathematically and applied in experimental work.
If the concentration and K a of a weak acid are known, the pH of the entire solution can be calculated. The exact method of calculation varies according to what assumptions and simplifications can be made. Weak acids and weak bases are essential for preparing buffer solutions, which have important experimental uses. Key Terms conjugate acid : the species created when a base accepts a proton conjugate base : the species created after donating a proton.
Learning Objectives Calculate percent dissociation for weak acids from their K a values and a given concentration.
Unlike K a , percent dissociation varies with the concentration of HA; dilute acids dissociate more than concentrated ones. Key Terms dissociation : the process by which compounds split into smaller constituent molecules, usually reversibly. Licenses and Attributions. If an acid is not listed here, it is a weak acid. All strong bases are OH — compounds.
When an ionic compound dissolves, it separates into its constituent ions:. This page was constructed from content via the following contributor s and edited topically or extensively by the LibreTexts development team to meet platform style, presentation, and quality:. It might also be helpful to learn the same about strong and weak bases.
I think it might have something to do with the electronegativity of the ions involved. It comes down to the strength of the bonds. Or that covalent bond strength is directly related to the bond dissociation energy and thus dissociation. From Atkins 9th Ed Now lets shift gears.
You may be familiar with bond enthalpy sometimes just called bond energies. It actually works out that there is a direct relationship to bond dissociation energy and bond enthalpy; which makes sense.
It is elegantly related by:. I guess the natural question to ask now is why do some bonds have a greater enthalpy of formation? This was not well understood for a long time. In reality there is a lot of factors that can come into play.
Because of the relationship with enthalpy, we can measure enthalpy with calorimetry and back calculate. The strength of an acid is expressed by its acidity constant, Ka.
The higher the value of the constant, the stronger the acid. Likewise, the strength of a base is expressed by its basicity constant, Kb. For a conjugate acid-base pair, in water, it is Ka. So, the rule is "the stronger the acid, the weaker the conjugate base and vice-versa", which is not exactly the same thing. Which is the weak and which is the strong? Sign up to join this community.
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