Acid-Base Equilibria Questions and Answers

Acid-Base Equilibria Questions and Answers Bronsted-Lowry Acid & Base: -Bronsted-Lowry Acid is the proton donor -Bronsted-Lowry Base is the proton acceptor Conjugate Acid & Base: -Conjugate Acid is formed from a Bronsted-Lowry Base accepting a proton -Conjugate Base is formed from a Bronsted-Lowry Acid donating a proton Lewis Acid & Base: -Lewis Acid is an electron pair acceptor -Lewis Base is an electron pair donor Arrhenius Acid & Base: -Acid produces an excess of H+ ions when it dissociates in an aqueous solution -Base produces an excess of OH- ions when it dissociates in an aqueous solution Describe the differences between the following pairs: -Bronsted-Lowry Acid & Bronsted-Lowry Base -Conjugate Acid & Conjugate Base -Lewis Acid & Lewis Base -Arrhenius Acid & Arrhenius Base An Arrhenius acid can be identified because their formula begins with an H. An Arrhenius base can be identified because their formula ends with an OH. How can you identify whether or not an acid or base is an Arrhenius one? An aqueous solution that resists changes in pH upon the addition of an acid or base. It is made either from a weak acid and its salt, which consists of the conjugate base and a cation, or from a weak base and its salt, which consists of the conjugate acid and an anion. What is a buffer solution? How is a buffer solution made? If a strong base is added, the acid in the buffer will neutralize the OH- ions. If a strong acid is added, the base in the buffer will neutralize the H3O+ ions. What will happen if a strong base is added to a buffer solution? What about a strong acid? 10:1 1:10 A buffer is considered to be effective when the HA/A- ratio ranges anywhere between __________ or _____________ By increasing the number of moles of the buffer in comparison to the moles of the strong acid/base. How can the effectiveness of a buffer be strengthened? Bicarbonate buffer system The ________________ is a system in our blood that helps us maintain a physiological level of pH using carbonic acid and bicarbonate ions Bicarbonate ions (HCO3-) Carbonic acid (H2CO3) Acidic Carbonic acid (H2CO3) Bicarbonate ions (HCO3-) Basic When an acidic substance enters our blood stream, the ________________ neutralizes the H3O+ ions, forming ________________ and water. This prevents the blood from becoming _________________. When a basic substance enters our blood stream, the ______________________ neutralizes the OH- ions, forming _________________ and water. This prevents the blood from becoming __________________. The bicarbonate buffer system. The reaction shown is an example of what? Stop working Denature Disable If our blood reaches a pH below physiological pH, the cells of our body will _______ _________________. Enzymes will _________________, which will ___________ their catalytic abilities 100% ionization Right-side Products When a strong acid/base undergoes equilibria, it undergoes _________________, which means that the total concentration of the acid turns into products. Because of this, equilibrium will lean to the __________-side of the reaction, favoring the _______________. Conjugate base Conjugate acid The stronger the acid, the weaker the _______________ will be. The stronger the base, the weaker the ______________ will be. Ionization Protonated Left-side Reactants When a weak acid undergoes equilibria, it does not undergo complete _______________. Weak acids are not able to donate their protons well, so it will stay mostly _______________. Because of this, equilibrium will lean towards the __________-side of the reaction, in favoring the ________________. Greater Less A solution would be considered acidic if the concentration of hydronium ions is _____________ than the concentration of hydroxide ions. A solution would be considered basic if the concentration of hydronium ions is _____________ than the concentration of hydroxide ions. Less than Greater than A solution would be acidic if it had a pH that is ________ than 7. A solution would be basic if it had a pH that is _______________ than 7 [H3O+] [OH-] In acid-base calculations: pH = -log_______ pOH = -log_______ 14 In acid-base calculations: pH + pOH = _________ Strong acids Examples of __________ ____________ includes the following: -HClO4 (perchloric acid) -HCl (hydrochloric acid) -HBr (hydrobromic acid) -HI (hydroiodic acid) -H2SO4 (sufuric acid) -HNO3 (nitric acid) Strong bases Examples of __________ ___________ includes the following: -NaOH (sodium hydroxide) -KOH (potassium hydroxide) -Ca(OH)2 (calcium hydroxide) -Mg(OH2) (magnesium hydroxide) Weak acids Examples of ___________ ____________ includes the following: -HF (hydrofluoric acid) -CH3COOH (acetic acid) -CH3OH (methanol) Weak bases Examples of ____________ ____________ includes the following: -NH3 (ammonia) -C6H5NH2 (aniline) Stronger Stronger The higher the Ka, the ____________ the acid. The higher the Kb, the _____________ the base. Lower Higher The ____________ the pKa, the stronger the acid. The ____________ the pKb, the stronger the base. 14. pKa + pKb = _________ acid-base neutralization reaction A ______________________________ reaction is a reaction between an acid and a base to form a solution of a salt and water. Sodium Chloride (HCl) pH = 7 neutral A salt formed from a strong base and a strong acid will result in a neutral solution. What is the salt formed from an acid-base neutralization reaction between HCl and NaOH? Would the pH of the solution be acidic, basic, or neutral? Explain why. Sodium acetate (CH3COONa) pH > 7 basic A salt formed from a weak acid and a strong base will result in a basic solution. What is the salt formed from an acid-base neutralization reaction between CH3COOH and NaOH? Would the pH of the solution be acidic, basic, or neutral? Explain why. Ammonium chloride (NH4Cl) pH < 7 acidic A salt formed from a strong acid and a weak base will result in an acidic solution. What is the salt formed from an acid-base neutralization reaction between HCl and NH3? Would the pH of the solution be acidic, basic, or neutral? Explain why. pH = pKa + log([A-]/[HA]) pOH = pKb + log([B+]/[HB]) The Henderson Hasselbalch equation: pH = _______ + log(________/_________) pOH = _______ + log(_______/________) pH or pOH The Henderson Hasselbalch equation is used to estimate the ________________ of a buffer solution. Increases Stronger Electronegative elements that are positioned closer to an acidic proton _____________ the acid strength by pulling electron density out of the bond holding the acidic proton. Furthermore, molecules with electronegative elements are ____________ in acid strength than molecules without electronegative elements. The one on the left is stronger since the electronegative atom (Cl) is closer to the red acidic proton in the left molecule than the right molecule. Of the two acidic molecules, which one is stronger? Explain your reasoning. Hydrolysis When a salt ion is split into an acid and base by the presence of a water molecule, this reaction is referred to as a ______________ reaction. Strong acid + strong base Strong acid + weak base Weak acid + strong base Weak acid + weak base The 4 kinds of neutralization reactions among acids and bases include: ____________ acid + ____________ base ___________ acid + _____________ base ___________ acid + _____________ base ___________ acid + ____________ base Polyvalent acid Polyvalent base A _______________ acid is an acid that is capable of donating more than one acid equivalent (H3O+) A _______________ base is a base that is capable of donating more than one base equivalent (OH-) or accepting more than one proton. Polyprotic species A ______________ species is a molecule that is capable of donating more than one proton. Polyvalent acids Examples of _______________ ______________ includes the following: -H2SO4 (sulfuric acid) -H3PO4 (phosphoric acid) -H2CO3 (carbonic acid)