Acid Base Equilibrium Unit Test Review PDF

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In depth organized review with diagrams and explanations that I created in order to study for the Academic Grade 12 Acid and Base Unit Test. ...

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Acid Base Equilibrium Unit Test Review Buffer Solutions • A buffer solution is created from an acid and its conjugate base or a base and its conjugate acid. • The buffer solution has both the acid or base and its conjugate and or base present in it, therefore, they can react with either an H + ion from a strong acid or an OH- ion from a strong base. This allows them to maintain a constant pH when a strong acid or base is added. • The addition of a strong acid or base to a buffer solution would shift the equilibrium, however, it would not drastically change the pH of the solution unless large quantities of the strong acid or base were added. • An example of a buffer solution is the buffer created by ammonia, a weak base, and ammonium, its conjugate acid. When HCl is added to this buffer, the NH3 reacts with the acid’s hydrogen ions to create NH4. Since the hydrogen ion’s then “locked up/attached” to the ammonium ion, it will not make a significant increase to the pH of the solution. When NaOH is added to the solotuion, the ammonium ion donates a hydrogen ion to the OH- ion to create ammonia and water, which would allow the pH of the solution to remain constant and not drastically change. • Bronsted-Lowry Theory of Acids and Bases • Defines an acid as a proton (hydrogen) donor. • Defines a base as a proton (hydrogen) acceptor. • In each solution where hydrogen ions are transferred, there must be an acid and a base present. The acid donates the hydrogen ion and the base accepts it. Autoionization of H 2O • Water can react with itself. • Water can act as an acid and a base, depending on the situation. • Pure water is constantly in equilibrium between its liquid and ion state. Calculating pH, pOH, [H+], [OH-] using Kw pH = -log[H +(aq) ] kw = [H+(aq)][OH -(aq)]

Properties of Strong/Weak Acids and Bases • A weak acid or base is a chemical that is either acidic or basic but doesn’t fully ionize when in solution. When added to water, the acid or base only partially dissolves, creating an equilibrium between its molecular form and ions. Their pH can be found if you have the [H+(aq)]. For weak acids, it’s direct calculations, but for weak bases, the [OH-(aq)] must be found first and the relationship between the ions and the Kw (with the Kw equation) could be used to find [H +(aq)]. o Weak acid ex., ethanoic acid. o Weak base ex., ammonia. • A weak acid is an acidic chemical that does not fully ionize when in solution. This means that the acid will not dissociate completely in water, so it is represented in equations that can go in both the forward and reverse direction. • A weak base is a basic chemical that does not fully ionize when in solution. This means that the base will not dissociate completely in water, so it is represented in equations that can go in both the forward and reverse direction. • A strong acid is an acidic chemical that fully ionizes when in solution. This means that the acid will completely dissociate in water, so it is represented in an equation with only one direction. • A strong base is a basic chemical that fully ionizes when in solution. This means that the base will completely dissociate in water, so it is represented in an equation with only one direction.

Equilibrium Constants • Kw: The water ionization constant (1.0 x 10-14 at SATP) • Ka: The equilibrium constant for an acid. [𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑠] 𝐾𝑎 = [𝑟𝑒𝑎𝑐𝑡𝑎𝑛𝑡𝑠] o The value of the acid ionization constant can be found from the chemical equation of the dissociation of an acid in water, acid ⇌ H+ + conjugate base when the concentrations of the acid, hydronium ions, and the conjugate base are known • Kb: The equilibrium constant for a base. [𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑠] 𝐾𝑏 = [𝑟𝑒𝑎𝑐𝑡𝑎𝑛𝑡𝑠] o The value of the base ionization constant can be found from the chemical equation of the dissociation of a base in water, base ⇌ OH - + conjugate acid when the concentrations of the base, hydroxide ions, and the conjugate acid are known Titrations • A titration is the procedure of finding the exact amount of a chemical that there is in a solution by gradually adding measured amounts of another chemical that reacts with the unknown chemical in a known way (i.e. colour change, precipitate formed, change in temperature or energy, etc.). • A titration is done by gradually adding a solution with a known concentration, the titrant, into another solution with an unknown concentration, the sample. The equivalence point is when the titrant is added to the sample during the titration, the chemicals in the solutions will react until they become chemically equivalent. This point is typically identified by the change in the colour of the solution that has both the titrant and the sample in it. When the colour of the solution containing the titrant and the sample has changed completely, it is referred to as the endpoint of the titration. Titrant: The solution with a known concentration. Sample: The solution with an unknown concentration. Primary Standards: Used to find the concentration of an acid or base. It’s a pure, stable compound which can be prepared in accurate concentrations. Equivalence Point: Small amounts of titrant are added to the sample; the chemicals will react until they’re chemically equivalent. Endpoint: When the colour change occurs.

Acidic, Basic, and Neutral Ions

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When an element/polyatomic in a compound is neutral, the other could be basic or acidic, so you have to find the ka and kb and whichever is greater is what it is. o ka > kb = acidic o kb > ka = basic...