Name: Period: Topic 8.3 - HW set 2 READ p. 355-359 and complete exercises #9-15 on p.360 Exercises 9 What happens to the pH of an acid when 10 cm3 of it is added to 90 cm3 of water? goes up I unit 10 Beer has a hydrogen ion concentration of 1.9 x 10-5 mol dm-3. What is its pH? 4.72 11 An aqueous solution has a pH of 9 at 25 ?. What are its concentrations for H. and OH? [H]=1X10 9M 12 For each of the following aqueous solutions, calculate [OH ] from [H] or [H ] from [OH-]. Classify each solution as acidic, basic, or neutral at 298 K. Kw (XID-14 [+]=1×10M (a) [+]= 3.4 x 10-9 mol dm-3 a)[OH]= CH+] = 3,4X 10-9= 2.94x10 OM PH= 8.47 basic (b) [OH-]= 0.010 mol dm-3 b) [H+] = LE - 14 11 1X 10- 12 M PH = 12 basic (c) [OH] = 1.0 x 10-10 mol dm- >THT7 15 14 0.01 =1x10-10= 0,000IM PH= 4 acidic basic (d) [H*] = 8.6 x 10-5 mol dm-3 d) 6H+7= 1X10- 14 8.6x10-5=1.16x10-10M PH = 9.94 13 What is the pH of 0.01 mol dm-3 solution of HCI which dissociates fully? PH =- log [0,0]= 2 HCI(aq) -> H*(aq) + Cl-(aq) 14 For each of the following biological fluids, calculate the pH from the given concentration of H* or OH- ions. 1 x 10 - 14 a) - 10g (8 x 10-8 ) = 6 b) PH = 2 (a) bile: [OH-] = 8 x 10-8 mol dm (b) gastric juice: [H*] = 10-2 mol dm-3 (c) urine: [OH-] = 6 × 10-10 mol dm3 1X10-14 c) - log (6x 10-10 ) =4.78 15 A solution of sodium hydroxide is prepared by adding distilled water to 6.0 g NaOH to make 1.0 dm3 of solution. What is the pH of this solution? Assume that NaOH dissociates completely in solution: NaOH(aq) -> Na*(aq) + OH-(aq) 6.0g NaOH 40g 1 mol dm3 1 = 0.15 moldm-3 1×10-14 PH =- 10g (0.15 = 13.2 0
Name: Period: pH AND pOH Name The pH of a solution indicates how acidic or basic that solution is. pH range of 0 -7 acidic : 7 neutral 7-14 basic Since [H+] [OH-] = 10-14 at 25° C, if [H+] is known, the [OH-] can be calculated and vice versa. PH = - log [H+] So if [H+] = 106 M, pH = 6. pOH = - log [OH-] So if [OH-] = 108 M, POH = 8. Together, pH + pOH = 14. Complete the following chart. [H+] pH [OH-] POH Acidic or Basic 1. 105 M 5 10° M . 9 Acidic 2. 10-7 M . 7 -7 10 M 7 neutral 3. 10-10 M 10 104 M 4 basic 4. 102 M 5. 10-3M 2 10-12M 3 10-11 M 12 . acidic 11 acidic 6. 7. 10 -12M .12 10-9M 9 11 8. 10-11 M 9. 10- M 1 10. 10-6 M 6 ID-2 M