UNIT 5 Assignment Acid-Base EQUILIBRIUM (Chap 4-pg & Chap 15-pg 667 & Chap 16 pg 701)

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1 UNIT 5 Assignment Acid-Base EQUILIBRIUM (Chap 4-pg & Chap 15-pg 667 & Chap 16 pg 701) The following refer to H 2 O (l) + 58 kj H + (aq) + OH (aq) Kw=1x :1. a) Does the thermodynamic trend to min P.E. ( H) favour the left side or right side b) Does the trend to max entropy ( S) favour the left side or right side c) Which of these trends gets stronger at higher temperatures d) Would you expect Kw to increase or decrease at higher temperatures e) do question 12 pg 751 5:2. Write the eq'm expression for the rx above. Kw = 5:3. At 25 C, what is a) [H + ] =..... b) [OH ] =....in pure water. A weak or strong electrolyte?... 5:4. a) If you add acid, does the water eq'm move left or right? b) What would happen to [OH - ] if you add acid to water? c) What would happen to [H + ] if you add base to water? 5:5. a) In a 1.0 x 10-1 M HCl sol n, what is i) [H + ] =... ii) ph =... b) In a 4.0 x 10-1 M HCl sol n, what is i) [H + ] =... ii) ph =... c) In a 1.0 x 10-3 M H 2 SO 4 sol n, what is i) [H + ] =... ii) ph =... d) In a 4.0 x 10-3 M HC 2 H 3 O 2 sol n, what is i) [H + ] =... ii) ph =... e) In a 1.5 x 10-4 M HNO 3 sol n, what is i) [H + ] =... ii) ph =... f) In a 1.0 x 10-1 M NaOH sol n, what is i) [OH ] =... ii) poh =... ph =... g) In a 4.0 x 10-1 M KOH sol n, what is i) [OH ] =... ii) poh =... ph =... h) In a 2.5 x 10-2 M NaOH sol n, what is i) [OH ] =... ii) poh =... ph =... i) In a 1.5 x 10-4 M Ba(OH) 2 sol n, what is i) [OH ] =... ii) poh =... ph =... 5:6. [H + ] [OH ] ph poh [H + ] [OH ] ph poh 1 x x x x x x 10 5 *ph calculations Attempt questions a) b) c) d) e) f) on page 697 *Solutions of strong acids & strong bases ph calculations 5.8. Attempt questions a) b) c) d) e) f) on page 697

2 * Solutions of weak acids & weak bases ph & pka calculations 5.9 Attempt questions a) 16.2 b) 16.3 c) on pg 752/ Attempt questions a) b) c) d) e) f) g) h) i) j) k) on page 754/55 5:11. A chemist dissolved 13.6 g of potassium bisulfate (KHSO 4 ) in 500 ml of water. Calculate a) the ph of the sol'n b) the % dissociation of i) the KHSO 4 ii) HSO 4 5:12. a) Calculate the Ka value for an acid if the ph of a 0.05 M sol'n is 2 b) Calculate the Ka value for an acid if the ph of a 0.20 M sol'n is 4. (You will be able to make a simplifying approximation in this case - mention it ) * Buffers 5:13. Attempt questions a) b) c) d) e) f) g) on pg 755 5:14. To study the effect of a weakly acidic culture medium on the growth of a certain strain of bacteria, a microbiologist prepared a buffer sol'n by making it 0.21 M NaC 2 H 3 O 2 (sodium acetate) and 0.14 M HC 2 H 3 O 2 ( acetic acid ). Using the Henderson-Hasselbalch eq'n, what is the ph of this sol'n? b) How well will this buffer work? Supposing M of a strong base ie NaOH were added to the buffer above, what would be the change in ph? *Acid-Base theories ( Arrhenius, Lowry-Bronsted, Lewis) Attempt a) b) on page Attempt questions a) 16.9 b) c) d) e) f) g) h) i) on pg 752/3 5:17. a) What is meant by the term amphoteric b) Write eq ns showing how the bisulfate ion, HSO 4, can act as a L-B acid & base. 5:18 Attempt questions a) b) c) on page 697 5:19. Complete the following reactions involving the hydronium ion. a) H 2 CO 3 + H 2 O c) HSO 4 + H 2 O b) NH 3 + H 3 O + 2 d) HPO 4 + H 3 O + 5:20. For each i) complete the eq'n ii) identify the acid-base pairs and iii) indicate which side would be favoured at eq'm. ( Ke < 1 or Ke > 1 ) + a) NH 4 + F b) C 6 H 5 COOH + CH 3 COO c) H 2 PO 4 + CN 2 d) H 2 CO 3 + CO 3 e) CH 2 ClCOOH + CCl 3 COO 5:21 Attempt questions a) & b) on page 695 in your text * 5.22 Attempt questions a) 15.4 b) 15.5 c) d) e) f) g) on pg 695 5:23. If we consider a mitochondrion in your cells a perfect cylinder 0.6 microns in diameter and 2.0 microns in length and has an internal ph of 6.8, how many H + ions does each one actually contain? b) If the wall ruptures and it loses 10 H + ions what will the new ph be? HINTS: V(cylinder) = π r 2 h; 1 micron=1x10-6 m ; 1 m 3 = 1x10 3 L ; 1 mol has x particles

3 LAB 5.1 : Acid / base identification lab NAME FORMULA acid/base?? ph(paper) ph(meter) pptl BTB MeO 1 vinegar 2 sodium acetate 3 lithium hydroxide 4 oven cleaner 5 Draino 6 NEET hair remover 7 saniflush 8 potassium bisulfate 9 sulfuric acid 10 sodium hypochlorite 11 aluminum hydroxide 12 Amphogel antacid 13 milk of magnesia 14 milk 15 lactic acid 16 nitric acid 17 ammonia 18 Windex 19 baking soda 20 baking powder 21 ginger ale 22 sodium phosphate 23 phosphoric acid 24 perchloric acid 25 lemon juice 26 vitamin C 27 aspirin 28 sodium hydroxide 29 boric acid 30 sodium borate 31 aluminum chloride 32 ferric chloride 33 hydrochloric acid 34 palmolive detergent 35 limewater 36 benzoic acid 37 oxalic acid 38 sodium nitrite 39 potassium oxalate 40 copper(ii) chloride

4 LAB 5.2: - Ka values and Buffers A) Prepare 250 ml of approx 5 x 10-3 M to 5 x 10-2 M solution in a volumetric flask for the acid you have chosen. ** NB: If the Ka you want to measure is a Ka 2 or Ka 3 then you must use the appropriate salt to make up the solution. Use the molar masses on the bottle as some acids and salts are hydrated. * we are finding the Ka ( ) for using. Ka = [ ] [ ] / [ ] ii) ph =. actual Ka =. B) Prepare 100 ml (in a beaker) of the buffered system you have chosen.you will have to calculate using the Henderson-Hasselbach eq n the correct ratio of weak acid to salt. Find the correct acid & salt, use the bottles for molar mass and make the sol n. Show all your calculations below. * we are making the../..buffer using.. as the weak acid and.. as the salt Once made measure the ph to see how close you came to your target ph i) target ph = ii) measured ph =. Now divide your buffer into two 50 ml aliquots to test it being stressed and obtain two 50 ml aliquots of distilled water for controls (assume a ph of 7 for the water) Add 25 ml of 0.1 M HCl to your buffer and the water, measure the new ph of both ph (buffer) =.. ph (buffer) =.. ph (water) = ph (water) =.. Add 25 ml of 0.1 M NaOH to your buffer and the water, measure the new ph of both ph (buffer) =.. ph (buffer) =. ph (water) = ph (water) =.. *write the eq ns for the rxs of the buffer + HCl,& buffer + NaOH to illustrate how it works

5 ACID-BASE THEORY -I A) Complete the following chart SOLUTION 18 M HCl 0.02 M Al(OH) 3 12 M H 2 C 2 O M KOH 0.1 M H 3 PO M KHSO M HC 2 H 3 O 2 STRONG/ WEAK DILUTE/ CONC PROTICITY/ BASICITY B) Predict whether the following substances or solutions are i) acid ii) base or iii) neither 1) ph = 10 2) [OH ] = 2 x ) accepts a proton 4) Cu(H 2 O) H 2 O H 3 O + + Cu(H 2 O) 3 (OH) +. 5) phenolphthalein solution is pink 6) NH 4 + H + + NH 3 7) [H + ] = [OH ] 8) donates a lone pair of electrons 9) N 2 H 4 + H + N 2 H ) Bromthymol blue solution is green 20) KC 2 H 3 O 2 (aq) 21) Phenolphthalein solution has no colour ) FeCl 3 (aq) 23) donates H + 24) KNO 2 ACID-BASE THEORY -II Each of the following reactions can be defined as an acid/base reaction. a) What is the simplest theory that can be used to identify the acid or base? b) Label the acid(s) -A, and base(s) - B. 1. NH 3 + H 2 O NH OH 2. AlBr 3 + :PCl 3 Br 3 Al:PCl 3 3. HNO 3 + water H + + NO 3 4. C 4 H 4 N + H 2 S C 4 H 4 NH + HS 5. HClO 4 + CO 3 2 HCO3 + ClO H + + H 2 O H 3 O + 7. NaOH(s) Na + + OH 8. BF 3 + C 2 H 5 OC 2 H 5 F 3 B:O(C 2 H 5 ) 2 11) HSO 4 H + + SO HBr + H 2 O H 3 O + + Br 12) HSO 4 + H + H 2 SO 4 13) [H + ] = 5 x ) NH 4 Cl (aq) 15) Methyl orange solution is pinkish 16) accepts a lone pair of electrons 17) Na 2 CO 3 (aq) 18) NaHCO 3 (aq) 19) poh = Co NH 3 Co(NH 3 ) H 3 PO 4 (l) H + + H 2 PO Na 2 CO 3 + H 2 O 2 Na + + HCO 3 + OH 13. AlF 3 + :NC 5 H 4 CH 3 F 3 Al:N-C 5 H 4 CH O 2 + (C 6 H 5 ) 3 CH (C 6 H 5 ) 3 C + OH Fe H 2 O Fe(H 2 O) 6...

6 Acid-Base Equilibrium (III) Assignment 1. a) DO QUESTION ON PAGE 756 IN YOUR TEXT. b) DO QUESTION ON PAGE 757 IN YOUR TEXT. c) Calculate the ph of a saturated solution of magnesium hydroxide. 2. If a M solution of a weak monoprotic acid(hx) is 13% ionized, calculate its Ka value. Using your green data sheet identify this acid by its Ka value. 3 DO QUESTION ON PAGE 756 IN YOUR TEXT. 4. a) DO QUESTION ON PAGE 756 IN YOUR TEXT. b) Calculate the ph of a 0.10 M KNO 2 solution 5. a) Al(NO 3 ) 3 b) K 2 CO 3 c) NaHSO 4 d) NH 4 Cl (i) Predict whether a 0.10 M solution of each of the salts above is acidic, neutral or basic. (ii) For each of the solutions that is not neutral, write a balanced chemical equation for a reaction occurring with water that supports your prediction.