יינון המים In the ionization of water, H+ is transferred from one H2O molecule to another. one water molecule acts as an acid, while another acts as a base. H2O(l) + H2O(l) H3O+(aq) + OH−(aq)

המשך יינון המים In water, H+ is transferred from one H2O molecule to another. one water molecule acts as an acid, while another acts as a base. H2O + H2O H3O+ + OH− .. .. .. .. :O: H + H:O: H:O:H + + :O:H− .. .. .. .. H H H water water hydronium hydroxide ion (+) ion (-)

קבוע שיווי המשקל של המים The ion product constant, Kw, for water at 25 C is the product of the concentrations of the hydronium and hydroxide ions. Kw = [ H3O+][ OH−] is obtained from the concentrations in pure water.

Pure Water is Neutral א. ריכוזי ההדרוניום וההדרוקסיד במים ניטרלים In pure water, the ionization of water molecules produces small but equal quantities of H3O+ and OH− ions.

Acidic Solutions ב. ריכוזי ההדרוניום וההדרוקסיד בתמיסה חומצית Adding an acid to pure water increases the [H3O+], decreases the [OH−], and causes the [H3O+] to exceed 1.0 x 10−7 M.

Basic Solutions ג. ריכוזי ההדרוניום וההדרוקסיד בתמיסה בסיסית Adding a base to pure water, increases the [OH−], decreases the [H3O+], and causes the [OH−] to exceed 1.0 x 10−7 M.

Comparison of [H3O+] and [OH−] סיכום Comparison of [H3O+] and [OH−]

[H3O+] and [OH−] in Solutions סיכום [H3O+] and [OH−] in Solutions In neutral, acidic, or basic solutions, the Kw at 25 C is always 1.0 x 10−14.

[H3O+] and [OH−] שלבים בחישוב ריכוזי הרחבה 8-14

דוגמא Calculating [H3O+] What is the [H3O+] of a solution if [OH−] is 5.0 x 10−8 M? Step 1 Write the Kw for water. Kw = [H3O+ ][OH− ] Step 2 Solve the Kw for the unknown [H3O+]. [H3O+] = 1.0 x 10−14 [OH−] Step 3 Substitute the known [OH−] into the equation and calculate. [H3O+] = 1.0 x 10

תרגיל 1 Learning Check If lemon juice has [H3O+] of 2 x 10−3 M, what is the [OH−] of the solution? A. 2 x 10−11 M B. 5 x 10−11 M C. 5 x 10−12 M

פתרון 1 Solution If lemon juice has [H3O+] of 2 x 10−3 M, what is the [OH−] of the solution? Step 1 Write the Kw for water. Kw = [H3O+][OH−] = 1.0 x 10−14 Step 2 Solve the Kw for the unknown [OH−]. [OH−] = 1.0 x 10−14 [H3O+ ] Step 3 Substitute the known [H3O+] into the equation and calculate. [2 x 10−3 ] Answer is C.

תרגיל 2 Learning Check The [OH−] of an ammonia solution is 4.0 x 10−2 M. What is the [H3O+ ] of the solution? 1) 2.5 x 10− 11 M 2) 2.5 x 10−12 M 3) 2.5 x 10−13 M

פתרון 2 Solution 3) 2.5 x 10−13 M [ H3O+] = 1.0 x 10−14 = 2.5 x 10−13 M 4.0 x 10−2