Document 242558
SCH3U-‐R.H.KING ACADEMY pH and Acidity Name: PRACTICE PROBLEM: 1. What is the molar concentration of hydronium ion in a solution of pH 8.25? [5.6 x 10-‐9 M] [H3O+] = 10-‐pH [H3O+] = 10-‐8.25 [H3O+] = 5.0 x 10-‐9 M 2. What is the pH of a solution that has a molar concentration of hydronium ion of 9.15 x 10-‐5M? [pH = 4.038] pH = -‐log [H3O+] pH = = -‐log[9.15 x 10-‐5M] pH = 4.038 3. What is the pOH of a solution that has a molar concentration of hydronium ion of 8.55 x 10-‐10 M? [pOH = 4.932] pH = -‐log [H3O+] pOH = 14 -‐ pH pH = -‐log[8.55 x 10-‐10 M] pH = 9.068 pOH = 14 – 9.068 pOH = 4.932 4. What is the molar concentration of hydronium ion in a solution of pH 2.45? [3.5 x 10-‐3 M] [H3O+] = 10-‐pH [H3O+] = 10-‐2.45 [H3O+] = 3.5 x 10-‐3 M 5. What is the pOH of a solution that has a molar concentration of hydronium ion of 4.99 x 10-‐4 M?[ pOH=10.698] pH = -‐log[4.99 x 10-‐4 M] pH = 3.302 pOH = 14 – 3.302 pOH = 10.698 6. What is the pH of a 3.4x10-‐5M H2SO4 solution? [pH = 4.17] H2SO4 + 2H2O 2H3O+ + SO42-‐ pH = -‐log[2 x H3O+] -‐5 -‐5 3.4x10 M 2 x 3.4x10 M pH = -‐log[2 x 3.4x10-‐5M] pH = -‐log[6.5 x 10-‐5 pH = 4.17 7. What is the pH of a solution if the pOH = 5? [pOH = 9] pOH + pH = 14 pH = 14 – pOH pH = 14 – 5 pH = 9 8. What is the pH of a 10-‐liter KOH solution if 5.611 grams of KOH were used to prepare the solution? [ pH = 12] KOH OH-‐ + K M = 0.1mol pOH = -‐log[OH-‐] 0.01M 0.01M 10L pOH = -‐log[0.01M] = 0.01M pOH = 2 pH = 14 -‐ 2 5.611g KOH 1 mol KOH = 0.1mol pH = 12 5.611g KOH H1 SCH3U-‐R.H.KING ACADEMY pH and Acidity Name: 9. If the pH of a KOH solution is 10.75, what is the molar concentration of the solution? What is the pOH? What is the [H3O+]?[pOH = 3.25],[ [H3O+]=1.8 x 10-‐11 M],[[KOH]=5.6 x 10-‐4 M] For pOH For (KOH )M For (H3O+) M KOH OH-‐ + K + pOH = 14 – pH [OH-‐] = 10-‐3.25 [H3O+] = 10-‐10.75 pOH = 14 – 10.75 [OH-‐] = 5.6 x 10-‐4 M [H3O+] = 1.8 x 10-‐11 M pOH = 3.25 [KOH] = 5.6 x 10-‐4 M 10. What is the pH of a 0.05 M H2SO4 solution? [pH=1]* 2H3O+ + SO42-‐ pH = -‐log [0.05M x 2] 0.05M 0.05M x 2 pH = -‐log [0.1M] pH = 1 11. What is the pH of a 0.50 M Ca(OH)2 solution? [pH=14] Ca(OH)2 2OH-‐ + Ca2+ pOH = -‐log[0.50M x 2] 0.50M 0.50M x 2 pOH = -‐log[1M] pOH = 0 pH = 14 12. Find the concentration of HNO3( aq) with a pH of 4.0 [1 x10 -‐4M] HNO3( aq) + H2O H3O+ + NO3-‐ [H3O+] = 10-‐4.0 [H3O+] = 1 x 10-‐4 M HNO3 = 1 x 10-‐4 M H2SO4 + 2H2O 13. Find the concentration of H2CO3( aq) with a pH of 6.0 [5 x10 -‐7M] H2CO3( aq) + 2H2O 2H3O+ + CO3 [H3O+] = 10-‐6.0 1 x 10-‐6 M H3O+ 1 mol H2CO3 [H3O+] = 1 x 10-‐6 M 2 mol H3O+ H2CO3 = 5 x 10-‐7 M 14. Find the concentration of KOH( aq) with a pH of 13.0 [1 x10 -‐1M] KOH OH-‐ + K [OH-‐] = 10-‐1.0 [OH-‐] = 1 x 10-‐1 M pOH = 14 – 13.0 KOH = 1 x 10-‐1 M pOH = 1.0 15. Find the concentration of Ba(OH)2( aq) with a pH of 9.0 [5 x10 -‐6M] Ba(OH)2( aq) 2OH-‐ + Ba2+ [OH-‐] = 10-‐5.0 1 x 10-‐5 M OH-‐ 1 mol Ba(OH)2 pOH = 14 – 9.0 [OH-‐] = 1 x 10-‐5 M 2 mol OH-‐ -‐6 pOH = 5.0 Ba(OH)2 = 5 x10 M H2 SCH3U-‐R.H.KING ACADEMY pH and Acidity Name: 16. Which is a higher concentration of hydronium ions, a solution with pH of 2 or a solution with pH of 3? pH 2 is more concentrated by 10 times. For pH 2 For pH 3 Each increment of pH level is 10 times more acidic and each [H3O+] = 10-‐2.0 [H3O+] = 10-‐3.0 decrement of pH level is 10 times + -‐2 + -‐3 [H3O ] = 1 x 10 M [H3O ] = 1 x 10 M basic. In this case, pH 2 is more concentrated by ten times because = 0.01 M = 0.001 M the difference between 2 and 3 is 1. 17. Which is a more acidic a solution, with pH of 4 or a solution with pH of 6? pH 4 is 100 times more concentrated. This is because the lower the pH, the more acidic a solution is and the difference between 4 and 6 is 2. Each pH level is 10 times more acidic. Therefore, 10 x 10 = 100. Therefore, its 100 times more concentrated H3
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