A strong acid is one that dissociates completely in water by donating one mole of protons per mole of acid to water. A weak acid only does this to a small extent. A strong base is one that dissociates completely in water by accepting one mole of protons per mole of base to water (or by releasing one mole of hydroxide ions per mole of base). A weak base only does this to a small extent. The strongest acid in water is hydronium ion (H₃O⁺), while the strongest base is the hydroxide ion (HO^-). Any acid stronger than hydronium will dissociate and donate its protons, leaving only its weak base behind. Likewise any stronger base than hydroxide will dissociate, leaving its weak acid partner behind. The strongest acid in ethanol will be C₂H₅OH₂⁺ while the ethoxide ion C₂H₅O^- is the strongest base (the reasoning is the same as it is for water).

HSO₄^- + H₃O⁺ since H₂SO₄is a strong acid, and so will donate a proton to water.

HCO₃^- + OH^- since water is a stronger acid than CO₃^2-

NH₃ + OH^- since water is a stronger acid

HPO₄^2- + SO₄^2- since HSO₄^- is a stronger acid

strongest acid = HClO₄
This can be looked up in a table of acids or bases, but can also be worked out by realizing that the number of oxygens will tend to polarize the bond attached to the hydrogen. More oxygens mean a more polar bond and one that is more likely to ionize in water. The weakest acid is HClO (for the opposite reason).

The strongest acid is HF (can be looked up) or worked out based on the relative ionic character of the bonds as determined by their electronegativity (as in exercise 3a). The weakest acid is H₂O.

the strongest acid is HNO₃, while the weakest is HClO.

The strongest base is PO₄^3- as looked up in an table of acids and bases or by considering which is the most likely to accept a proton from water. The proton will be strongly attracted by the greater negative charge. The weakest base is H₂PO₄^-.

The strongest base will be CH₃^-, while the weakest base will be hydroxide (can see this on a table of conjugate bases).

The strongest  base will be F^- since it will have the greatest tendency to accept a proton.  The weakest base will be Br^-. In order of strength: F^- > Cl^- > Br^-.

0.162 M

As a diprotic acid, oxalic acid dissociates 2 proton equivalents per molecule. Phenolphthalein is used as an indicator to determine the equivalence point of the reaction; that is, the point at which all sodium hydroxide is reacted with oxalic acid. This means that the molar ratio of sodium hydroxide to oxalic acid will equal the molar ratio of the following balanced equation, which is 2 NaOH: 1 H₂C₂O₄

H₂C₂O₄ + 2 NaOH              C₂O₄^2- + 2 H₂O

 1. Determine moles of NaOH

 2. multiply by molar ratio of oxalic acid to sodium hydroxide

 3. determine molarity of H₂C₂O₄ using the volume titrated.

pH = 4.61

In order to solve this problem, you will need to consider the species that are present in solution: undissociated CH₃COOH, CH₃COO^- (from dissociated acetic acid and sodium acetate, which dissociates completely because it is a sodium salt) and H₃O⁺ (formed from the dissociated proton from acetic acid).  

The pH of the buffer solution can be calculated using the initial concentrations of ions and the Ka of acetic acid.

• Molarity of CH₃COOH (M=60g/mol) = 25 g/ 60 g/mol / 1 L = 0.42 M
• Molarity of NaO₂CCH₃ (M= 82 g/mol) = 0.30 M

Now we need to consider the extent to which each species listed above is found in solution at equilibrium. Keep in mind that all NaO₂CCH₃ dissociates completely to yield 0.3 M CH₃COO^- in solution. This results in the common ion effect in which the solubility of a solid is reduced if the solution already contains ions common to the solid (in this case the common ion is CH₃COO^-). To see this effect more clearly, it is helpful to set up an “ICE” table that lists the Initial concentrations, the net Change in concentrations and the concentrations of ions at Equilibrium. The change that occurs for each chemical species is according to stoichiometric equivalents, with reactant species showing a decrease in concentration and products increasing in concentration.

Filling in the equilibrium values to the K_a formula gives:

Because the K_a is a relatively small value, the above equation may be simplified and the answer estimated to avoid solving for a quadratic equation. It is acceptable to simplify equations so long as the amount of ions dissociated is less than 5% of the initial molecular concentration (if you simplify, be sure to check for this at the end). The simplified equation is:

 checking for the 5% dissociation rule shows that only a very small percentage dissociates;

Because the question asks for the pH, solve for the concentration of H₃O⁺ and calculate pH