Sec Unit Review

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1 hemistry 12 Sec Sec Unit Review Name ue ate 1. What colour would 1.0 M Hl be in an indicator mixture consisting of phenol red and thymolphthalein? red blue yellow colourless 2. uring a titration, what volume of M KOH is necessary to completely neutralize 10.0 ml of 2.00 M H 3 OOH? 10.0 ml 20.0 ml 25.0 ml 40.0 ml 3. Which indicator has a Ka = 1.0 x 10-6? neutral red thymol blue thymolpthalein chlorophenol red 4. cid is added to a buffer solution. When equilibrium is reestablished the buffering effect has resulted in [H 3 O + ] increasing slightly decreasing slightly increasing considerably decreasing considerably 5. buffer solution will form when 0.10 M NaF is mixed with an equal volume of 0.10 M HF 0.10 M Hl 0.10 M Nal 0.10 M NaOH 6. What is the [H 3 O + ] at the equivalence point for the titration between Hr and KOH? 1.0 x 10-9 M 1.0 x 10-5 M 1.0 x 10-7 M 0.0 M 7. Which of the following would form a buffer solution when equal moles are mixed together? Hl and Nal HN and NaN KNO 3 and KOH Na 2 SO 4 and NaOH 8. Which of the following will dissolve in water to produce an acidic solution? O 2 ao MgO Na 2 O 1

2 hemistry 12 Sec In a titration, which of the following has a ph = 7.00 at the equivalence point? NH 3 and HNO 3 KOH and Hl NaF and Hl a(oh) 2 and H 3 OOH 10. What is the approximate Ka value for the indicator chlorophenol red? 1 x x x x Which of the following titrations will always have an equivalence point at a ph > 7.00? weak acid with a weak base strong acid with a weak base weak acid with a strong base strong acid with a strong base 12. buffer solution may contain equal moles of weak acid and strong base strong acid and strong base weak acid and its conjugate base strong acid and its conjugate base 13. gas which is produced by burning coal and also contributes to the formation of acid rain is H 2 O 3 SO 2 3 H When the indicator thymol blue is added to 0.10 M solution of an unknown acid, the solution is red. The acid could be HF H 2 S HN HNO onsider the following graph for the titration of 0.1 M NH 3 with 1.0 M Hl. ph I II III IV Volume Hl added buffer solution is present at point. I. II. III. IV 2

3 hemistry 12 Sec onsider the following equilibrium system for an indicator: HInd + H 2 O H 3 O + + Ind - Which two species must be of two different colours in order to be used as an indicator?. HInd and H 2 O. H 3 O + and Ind -. HInd and Ind -. Hind and H 3 O Which of the following indicators is yellow at ph 10.0?. methyl red. phenol red. thymol blue. methyl violet 18. sample containing 1.20 x 10-2 mole Hl is completely neutralized by ml of Sr(OH) 2. What is the [Sr(OH) 2 ]? x 10-3 M x 10-2 M x 10-1 M. 2.4 x 10-1 M 19. Which of the following titrations will have the highest ph at the equivalence point?. Hr with NH 3. HNO 2 with KOH. Hl with Na 2 O 3. HNO 3 with NaOH 20. The ph of 0.10 M KOH solution is n indicator changes colour in the ph range 9.0 to What is the value of the Ka for the indicator?. 1 x x x x Which of the following always applies at the transition point for the indicator Hind?. [Ind - ] = [OH - ]. [HInd] = [Ind - ]. [Ind - ] = [H 3 O + ]. [HInd] = [H 3 O + ] 23. onsider the following equilibrium for an indicator: HInd + H 2 O H 3 O + + Ind - In a solution of ph of 6.8, the colour of bromthymol blue is. blue because [HInd] = [Ind - ]. green because [HInd] = [Ind - ]. green because [HInd] < [Ind - ]. yellow because [HInd] > [Ind - ] 24. The indicator with Ka = 4 x 10-8 is. neutral red. methyl red. indigo carmine. phenolphthalein 3

4 hemistry 12 Sec In a titration a ml sample of Sr(OH) 2 is completely neutralized by ml of M Hl. The concentration of the Sr(OH) 2 is x 10-3 M x 10-3 M x 10-2 M x 10-1 M Sec Ka and Kb alculations 1. alculate the [H + ], [OH - ], ph, and poh for 0.20 M HN. [H + ] = [OH - ] = ph = poh = 2. alculate the [H + ], [OH - ], ph, and poh for 2.20 M HF. [H + ] = [OH - ] = ph = poh = 3. alculate the [H + ], [OH - ], ph, and poh for M H 3 OOH. [H + ] = [OH - ] = ph = poh = 4. alculate the [H + ], [OH - ], ph, and poh for 1.65 M H 3 O 3. [H + ] = [OH - ] = ph = poh = 5. alculate the ph of a saturated solution of Mg(OH) 2. tough one! 6. alculate the ph of a M weak diprotic acid with a Ka = 1.8 x ml of 0.20M Sr(OH) 2 is diluted by adding ml of water, calculate the ph of the solution. 8. How many grams of H 3 OOH are dissolved in 2.00 L of a solution with ph = 2.45? Sec 4.16, 4.18 Titration 1. alculate the volume of 0.200M H 2 SO 4 required to neutralize 25.0 ml of 0.100M NaOH. 2. escribe how a primary standard is used. 4

5 hemistry 12 Sec onsider the following reaction: 2Hl + a(oh) 2 al 2 + 2H 2 O When 3.16g samples of a(oh) 2 were titrated to the equivalence point with an Hl solution, the following data was recorded. Trial Volume of Hl added # ml # ml # ml alculate the original [Hl] 4. What type of titration curves are buffer regions found? Why? 5. What indicator would be used if the equivalence point has a ph of 4.5? Why? 6. raw the following titration curves. ccurately label the initial and final ph and the equivalence point. Label the axis. Strong acid Strong ase Weak cid - Strong ase Initial ph = ph at EP = final ph = Initial ph = ph at EP = final ph = 5

6 hemistry 12 Sec Weak ase Strong cid Strong ase Strong cid Initial ph = ph at EP = final ph = Initial ph = ph at EP = final ph = The following titration curve results from titrating 25.0 ml of a 0.10 M Weak cid H with a Strong ase KOH: ph Volume of KOH (ml) a.) Use this graph to estimate the Ka of the acid H. b.) Use this graph to calculate the [KOH]. 6

7 hemistry 12 Sec Sec 4.17 Indicators 1. efinition 2. Equilibrium equation 3. olors for methyl orange HInd Ind - 4. ompare the relative sizes of [HInd] and [Ind - ] at the following ph s for methyl orange. ph = 2.0 ph = 3.7 ph = 5.0 olor Relationship 5. Hl is added to methyl orange, describe if each increases or decreases. [H + ] [HInd] [Ind - ] olor hange 6. NaOH is added to methyl orange, describe if each increases or decreases. [H + ] [HInd] [Ind - ] olor hange 7. State two equations that are true at the transition point of an indicator. 8. What indicator has a Ka = 4 x What is the Ka for methyl orange? 10. solution is pink in phenolphthalein and colorless in thymolphthalein. What is the ph of the solution? 11. solution is blue in bromothymol blue, red in phenol red, and yellow in thymol blue. What is the ph of the solution? Sec 4.19 uffers 1. efinition 7

8 hemistry 12 Sec cid onjugate ase Salt HN KHO 3 NH 3 HF NaH 3 OO - H 2 O 4 3. Write an equation for the first three buffer systems above. 4. Which buffer could have a ph of 4.0? Which buffer could have a ph of 10.0? a) Hl & Nal b) HF & NaF c) NH 3 & NH 4 l 5. Predict how the buffer of ph = 9.00 will change. Your possible answers are 9.00, 8.98, 9.01, 2.00, and Final ph a) 2 drops of 0.10 M Hl are added b) 1 drop of 0.10 M NaOH is added c) 10 ml of 0.10 M Hl are added 6. Write an equation for the carbonic acid, sodium hydrogencarbonate buffer system. few drops of Hl are added. escribe the shift and each concentration change. Equation: Shift [H + ] = [H 2 O 3 ] = [HO 3 - ] = Sec nhydrides, cid Rain 1. State whether the following compounds will act as acids () or bases () when added to water. (10 marks) 8

9 hemistry 12 Sec a) FO 2... d) O 2... b) ao... e) g 2 O... c) r 2 O 3... f) s 2 O a) efine a basic anhydride (1 mark) - 3. a) efine an acidic anhydride (1 mark) - 4. Normal (unpolluted) rain water usually has a ph of about. This is less than 7 due to gas dissolving in the air 5. cid rain could be defined as rain having a ph below. 6. Give two formula equations which show how sulphurous acid can be produced starting with sulphur. (2 marks) Give three formula equations which show how sulphuric acid can be produced starting with sulphur. (3 marks) Give the balanced equation for the formation of NO 2 from it s elements. (1 mark) 13. Give the balanced equation for the formation of nitrous and nitric acid from NO 2 dissolving in rain water. (1 mark) 9