1 Identify the following acid base or both or salt a NH3 base weak base b HC2H3O2 acid weak acid c HSO4 both d CH3COO base conjugate base of acetic acid cannot act as acid e H2O both f HCN acid weak acid g NaCl salt neutral salt 2 Determine whether the following compounds are strong or weak acids bases strong acid weak acid a HCl b HF c NaOH strong base d NH weak base e NH4 weak acid 3 Consider the following acids and their conjugate base rank the stability of their conjugate base from most to least stable in other words strongest to weakest acid a HNO strong acid with more oxygen b HF c CH COOH weak and not lower electroneg d HCl strong acid no oxygen weak acid high electroneg Ans A D B C 4 A solution has an OH concentration of 3 2 10 M What is the H Use pOH log OH pOH log 3 2 10 5 49 Use pH pOH 14 pH 14 5 49 8 51 10 pH H 3 125 E 9 don t round numbers only at the end OR Kw OH H 3 125 E 9 5 What is the pOH of a solution with a H O of 2 5 10 M pOH 9 4 Ca OH 6 How many mL of 0 500 M H PO are needed to neutralize 25 0 mL of 0 250 M Balanced reaction 2 H PO 3 Ca OH Ca PO 6 H O 0 25 M Ca OH 0 025 LCa OH 1 2mol H PO 3mol Ca OH 1 L 0 5mol 0 00833 L 8 33mL H PO you can use M V M V ONLY FOR 1 1 Ratio it s just confusing if you have diff stoich 7 What mass of KOH would need to be dissolved in 500mL of water to produce a solution with a pH of 12 4 pOH 14 pH 1 6 OH 0 0251M 0 0251 mol L 0 5 L 0 0126 mol OH 0 0126 mol KOH 1 1 ratio 0 0126 mol KOH 56 11 g mol 0 7g KOH 8 What is the pH of 0 32M Ca NO2 2 Ka of HNO2 is 4 5E 4 Kw Ka Kb Kb 2 22 E 11 Set Kb expression The Ca NO dissociates in water Ca NO Ca2 2NO The NO ions are the conjugate bases of HNO nitrous acid and they will hydrolyze react with water to form OH hydroxide ions and HNO The hydrolysis reaction is NO H O HNO OH H2O HNO2 OH I C E I C NO2 0 32 2 x 0 64 NH3 1 75 x Kb x 2 0 64 solve for x x 3 77 E 6 OH Solve for pOH 5 42 14 pOH pH 8 58 9 What is the pH and the percent ionization of a 1 75M NH3 solution when it has reached equilibrium Kb 1 8x10 5 H2O NH4 0 x OH 0 x 0 x x 0 x x E 1 75 x x x Solve for x 5 61 E 3 OH find pOH then pH 11 75 ionization OH NH3 5 61 E 3 1 75 100 0 321 10 Consider all of the equilibria occurring for H3PO4 Which of the species within this series will be amphoteric able to react both as a base and as an acid H PO aq H O aq a First Ionization H PO aq H O l b Second Ionization H PO aq H O l HPO aq H O aq c Third Ionization HPO aq H O l PO aq H O aq Identify acid and conjugate base that can act as both acid and base which Ans H PO HPO 11 An unknown weak base with a concentration of 0 091M has a pH of 11 7 What is the Kb I C E pOH 14 11 7 2 3 OH 5 0119 E 3 equals x 0 091 B x 0 091 x Kb OH HB B 2 9E 4 Kb H2O HB OH 0 x x 0 x x 12 What is the pH of a solution that results from adding 15 mL of 1 75 M KHSO3 to 25 mL of a 3 5 M K2SO3 pKa 10 45 Find moles of acid and base 0 015 L 1 75 M 0 0263 mol KHSO3 acid 0 025 L 3 5 M 0 0875 mol K 2SO3 base pH 10 45 log 0 0875 0 0263 10 97 13 Using Q12 what is the new pH if you add the following a 15 mL of 0 55 M HCl 0 015 L 0 55 M 0 00825 mol HCl acid pH 10 45 log 0 0875 0 00825 0 0263 0 00825 10 8 pH logKa log base acid acid acid pH 10 8 b 25 mL of 0 75 M NaOH 0 025 L 0 75 M 0 0188 mol NaOH base pH 10 45 log 0 0875 0 0188 0 0263 0 0188 11 6 log base base acid base pH 11 6 14 What is the HAc and Ac for an Acetic Acid Acetate buffer system with a molarity of 0 680 M and a pH of 4 37 and a pKa of 5 13 HAc Ac 0 68M 4 37 5 13 log log this is the ratio which indicates 0 174 HAc Ac plug this to 1st eqn acid conj Base buffer so we re gonna do substitution 1 HAc 0 174 HAc 0 68M solve for HAc then solve for Ac HAc 0 579 M Ac 0 101 M 15 A titration of 30ml of H3PO4 solution of unknown concentration with a standardized 1 05M Ca OH 2 solution requires 40 2 mL to reach the 3rd equiv pt What is the concentration of the H3PO4 solution 2 H PO 3 Ca OH Ca PO 6 H O 40 2mL 0 0402 L Ca OH 2 0 0402 LCa 0 02814 mol H PO 0 03 L 0 938 M H PO a HF b HF and F c F d OH 16 What is the primary species in the solution at point A B C D HF NaOH 17 Calculate the pH at the points indicated below if 50 0 mL of 0 100 M aniline hydrochloride is titrated with 0 185 M NaOH Ka for aniline hydrochloride is 2 4 x 10 5 aq OH aq C6H5NH2 aq H2O C6H5NH3 a before the titration begins Aniline hydrochloride formula is C6H5NH3 form an acidic solution Cl is a salt of the weak base aniline The salt will C6H5NH3 aq H2O C6H5NH2 aq H3O aq 2 4 10 5 x2 0 1 x 0 00155 M pH 2 81 b at the equivalence point 1 Calculate moles of aniline hydrochloride initially present 0 100 mol L 0 0500 L 0 00500 mol 2 Calculate the volume of NaOH solution required to reach equivalence point 0 185 mol L x 0 00500 mol x 0 0270 L 27 0 mL 3 Calculate …
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