Acids & Bases Lesson 9 pH, pOH, Kb for Weak Bases.

Slides:

Advertisements

Similar presentations

Go over Ch Test Summary of this week Questions over the reading Discussion / explanation Homework.

Advertisements

Section 18.3 Hydrogen Ions and pH

1 Acetic acid, has a K a of 1.7 x Determine the pH of a 0.10 M solution of acetic acid. Hint: First write out the equilibrium expression of the.

Finding the pH of a Weak Base

Acids & Bases Lesson 4 Relative Strengths of Acids and Bases.

8.7 Acid-Base Titration Learning Goals … … determine the pH of the solution formed in a neutralization reaction.

Relationship Between Ka and Kb. Consider the dissociation of a weak acid: CH 3 COOH (aq) + H 2 O (l)  H 3 O + (aq) + CH 3 COO - (aq) K a = [H 3 O + ][CH.

دکتر امید رجبی دانشیار گروه شیمی دارویی شیمی عمومی.

Final Exam Review. Oxoacids Central element, surrounded by oxygens e.g. (not all listed) Recognizing Acids Hydrohalic Acids Group 7 ion with H+ HF, HCl,

Wake-up Write down each equation below. Identify the base (B), acid (A), conjugate acid (CA), and conjugate base (CB). 1.NH 3 + HCN  NH 4 + CN 1.HSO 4.

8.2 Strong and Weak Acids and Bases

Strong Acid-Base Calculations

Ionization of Water (Kw), Ka and Kb intro.

Strong Acid-Base Titrations Chapter 17. Neutralization Reactions Review Generally, when solutions of an acid and a base are combined, the products are.

Unit 13 Marker Board Review Acids & Bases You need a marker board, marker, eraser, calculator, & periodic table.

Acid-Base Equilibria and Solubility Equilibria Chapter 16 Dr. Ali Bumajdad.

Acids & Bases Lesson 5 pH scale. H and OH There is a way we can connect both H and OH together, using what we already know about them. We know: Kw = [H.

Weak Acids & Weak Bases. Review Try the next two questions to see what you remember Try the next two questions to see what you remember.

Acids & Bases Hydrolysis Lesson 7. Hydrolysis Hydrolysis of a salt is… The reaction between water and the cation or anion ( or both) that make up the.

Review of Acids. HClStrong Acid HCl  H + + Cl M pH = -Log[H + ] =1.0 No ICE HFWeak Acid HF ⇌ H + + F - I0.10 M00 CxxxCxxx E xxx small Ka.

8.3 Bases Similar to weak acids, weak bases react with water to a solution of ions at equilibrium. The general equation is: B(aq) + H2O(l)  HB+(aq) +

1 Acid-Base Reactions Chapter Acid-Base Reactions Reactions always go from the stronger A-B pair (larger K) to the weaker A-B pair (smaller K).

Acids Lesson 12 Calculating Ka From pH. 1.The pH of M H 2 C 2 O 4 is Calculate the Ka for the weak acid.

Acids Lesson 8 Weak Acids pH, Ka Calculations.

Mixing Acids With Bases (Disclaimer: not even remotely as visually stimulating as the picture below)

Lets walk through them all together:

Stay Strong or Be Neutral

Acids and Bases. Dissociation of Strong Bases  Strong bases are metallic hydroxides  Group I hydroxides (NaOH, KOH) are very soluble  Group II hydroxides.

Solubility Lesson 3 Calculating Ksp.

U2 S2 L4 Ka and Kb calculations p : pH and Ka of a Weak Acid p : The Base Dissociation Constant, Kb Homework: p 591: # 5, 6, 7, 8, 9 and.

Salt Hydrolysis. Salts Ionic compound made up of CATION and ANION Has acidic and basic properties Based on ions produced when salts dissociate No acid/base.

PH of Salts When acids are neutralized by bases, water and a salt is formed. The salt solution can be acidic, basic, or neutral depending on the acid.

Hydrolysis of Salts December What we know so far…. Bronsted-Lowry AcidsBronsted-Lowry Bases Donate H + (protons) Criteria to be an acid: Must have.

Due: Acid WS Today: 1.Bases 2.pOH 3.Relationship between pOH and pH HW Base & pOH WS.

Acids & Bases Lesson 6 Strong Acid-Base Calculations.

Logarithms. The logarithm of a number is the number of times 10 must be multiplied by itself to equal that number.

 Strength of the Acid.  K W of water.  pH scale.  pH calculation:  pH of Strong monoprotic acid/base.  pH of weak monoprotic acid/base.  pH of.

Acids Lesson 16 Amphiprotic Ions Acids or Bases?.

PH. Ionization of Water  When compounds dissociate/ionize in an aqueous solution, they produce ions - hydronium (H 3 O + ) and hydroxide (OH - )  These.

Acids and Bases.

Acid-Base Equilibria and Solubility Equilibria

Monday May 18 Objective: Calculate the pH of any solution. Checkpoint:

Acids and Bases Bundle 4: Water.

Titration and pH Curves.

Neutralization Reactions ch. 4.8 and ch. 15

Strength of Acids and Bases

Acid-Base Equilibria and Solubility Equilibria

Autoionization of Water

Acid-Base Equilibria and Solubility Equilibria

Acids and Bases Bundle 4: Water.

Acids and Bases Bundle 4: Water.

Acids and Bases.

Review of Acids.

Acids & Bases Ch12 in text.

Salts product of neutralization reaction strong base strong acid

SAMPLE EXERCISE 17.6 Calculating pH for a Strong Acid–Strong Base Titration Calculate the pH when the following quantities of M NaOH solution have.

Acid-Base Equilibria and Solubility Equilibria

Acid-Base Equilibria and Solubility Equilibria

Titration of Weak acids

EXAM #2 H2CO3   HCO H ; Ka1 = 4.3 x 10-7

Acids Lesson 13 pH for Weak Bases.

Salts product of neutralization reaction strong base strong acid

Acids Lesson 10 Calculating Ka From pH.

Warm Up #7 1. Is magnesium hydroxide a weak or strong base?

Acid-Base Equilibria and Solubility Equilibria

Acids Lesson 9 Weak Acids pH Calculations.

Acids Lesson 8 Ionization of Water pH Calculations.

AP Chem Take out HW to be checked

Acid-Base Equilibria and Solubility Equilibria

Presentation transcript:

Acids & Bases Lesson 9 pH, pOH, Kb for Weak Bases

Weak Bases calculations Helpful Hints: -Weak bases do NOT ionize 100% -There is an equilibrium state -NEED….ICE tables! -Kb can’t be used directly from table…use -Kb = kw/Ka

You can calculate the Kb using the Ka from the table and the equation below. KaxKb=1.0x o C Kb=Kw Ka(conjugate) or Ka=Kw Kb(conjugate)

Weak Bases calculations Two types of questions -calculate pOH, or [OH - ] -calculate Kb

1.Calculate the pH of 0.50 M NH 3. Weak BaseNeed Kb(NH 3 ) = Kw Ka(NH 4 + ) =1 x x =1.786 x NH 3 + H 2 O ⇄ NH 4 + +OH - I0.50 M00 C-x xx E x xx Small Kb 0

Kb=[NH 4 + ][OH - ] [NH 3 ] =x 2= x x = M= [OH - ] pOH = 2.52pOH= -Log[OH - ] pH + pOH = pKw = pH = 11.48

2.Calculate the pH of 0.20 M Na 2 CO 3. Weak BaseNeed Kb(CO 3 2- ) = Kw Ka(HCO 3 - ) =1 x x =1.786 x CO H 2 O ⇄ HCO 3 - +OH - I0.20 M00 C-xxx E xxx Small Kb 0

Kb=[HCO 3 - ][OH - ] [CO 3 2- ] =x 2 = x x = M pOH = 2.22 pH = 11.78

TRY: calculate [H + ], [OH - ], pH, pOH for a 0.20 M solution of NH 3.

3.Calculate the pH of 0.20 M NaCl. NaCl is a neutral salt pH=7.00

What if asked to calculate K b ? K b indicates weak bases, then use ICE tables. need to know [ ]’s to plug in the equation.

EX:If the pH of 0.40 M NH 25 o C is , calculate the Kb. NH 3 + H 2 O ⇄ NH 4 + +OH - pH =11.427pOH = [OH - ] = [OH - ]= M at equilibrium line!!! [NH 4 + ][OH - ] [NH 3 ] ICEICE ( ) = 1.8 x Kb ==

TOGETHER: The pOH of a 0.50 M solution of the weak acid HA is what is K b for A - ?

TRY: A M solution of the weak base hydroxylamine, NH 2 OH, has a pH of What is K a for NH 3 OH + ?

Next question Strong acid and a strong base Calculate excess No ICE tables

mL of 0.20 M HNO 3 reacts with 40.0 mL of 0.20 M KOH, calculate the pH of the resulting solution.

Next question It says saturated solution = equilibrium This is a solubility equilibrium- no ICE Remember, unit 3!

4.Calculate the pH of a saturated solution of Mg(OH) 2. This is a solubility equilibrium- no ICE Mg(OH) 2(s) ⇄ Mg 2+ +2OH - ss2s Ksp=[Mg 2+ ]][OH - ] 2 = 5.6 x [s][2s] 2 = 5.6 x s 3 = 5.6 x s=1.119 x M

2s = [OH - ]=2.237 x M pOH=3.65 pH=10.35

Be careful Are they strong or weak acids and bases? calculations differ! Use ICE tables for only weak combinations. Is it a Ksp question? Always understand the question BEFORE answering it. Remember ALL the equations!

pHEquations You must know the following equations, which are all based on the ionization of water at 25 0 C! H 2 O ⇄ H + +OH - Kw=[H + ][ OH - ]=1.00 x pH=-Log[H + ]OrpOH=-Log[OH - ] [H + ]=10 -pH [OH - ]=10 -pOH pH+pOH=pKw=14.000

Homework p , 86, 87, 88, p , 91, 93.