Acids and Bases Student 10

8/13/2019 Acids and Bases Student 10

1/11

ACIDS AND BASES Chapters 14-15

What is an Acid? 5 general properties were observed

Aqueous solutions taste sour

Change color of acid-base indicators

Some react with active metals to release H2gas

React with bases to produce salts and water

Conduct electric current

REVIEW: Naming Acids Common Acids

Sulfuric Acid

Nitric Acid

Phosphoric Acid

Hydrochloric Acid

Acetic Acid


2/11

What is a Base? 5 general properties were observed

Aqueous solutions taste bitter

Change the color of acid-base indicators

Dilute solutions feel slippery

React with acids to produce salts and water

Conduct electric current

Arrhenius Acids and Bases

Arrhenius acid

Arrhenius base

Aqueous solutions of acids

Brnsted-Lowry Acids and

Bases Brnsted-Lowry Acid

Brnsted-Lowry Base

Brnsted-Lowry Reactions

Whats the difference? Why have 2

definitions?

Conjugate Acids and Bases

A Brnsted-Lowry Acid gives up a

proton, it creates_________________

If the reaction is reversible, that

________ acts like a ___________

HF + H2O F-+ H3O

+


3/11

Lewis Acids and Bases

Another definition of acids and bases

Lewis acid

Lewis base

Lewis acid-base reaction

Summary

Identify each type of acid and base

NaOHNa+ + OH-

HF + H2OF- + H3O+

H++ NH3NH4+

Strength of Acids

Strong acid

Strength depends on polarity of bonds

Acid strength increases with ____________

polarity and _____________ bond energy

Weak Acids


4/11

Memorize Strong Acids!!! Strength of Bases

Alkaline

Strong bases

Weak bases

Memorize Strong Bases!!!

Strengths of Conjugate Acids/Bases


5/11

Amphoteric Compounds

Amphoteric

Most common amphoteric compound

Monoprotic and Polyprotic

Acids

Monoprotic HCl + H2O

Diprotic

H2SO4+ H2O

Triprotic

H3PO4+ H2O

Predicting Directions of Reactions

HClO4+ H2OH3O++ ClO4

-

CH3COOH + H2OH3O++ CH3COO

-


6/11

Self Ionization of Water

Since water is amphoteric, we know that it canform H+and OH-ions.

This occurs all the time; water is a WEAK

electrolyte

So weak that the concentrations of ions areeach 1.0 x 10-7 M

Ionization Constant of Water

Product of concentrations of H3O+and OH-ions

is a constant, kw

Kw= 1.0 x 1014 M2

Because hydronium and hydroxide ions areequal in water, its neutral

More hydronium =

More hydroxide =

Calculating [H3O+] and [OH-]

NaOH (s)

If 0.01mol of NaOH is added to 1L of

water, how much OH-will be produced?

Basic or acidic?

What is the concentration of H3O+?

The pH Scale

Indicates concentration of H3O

From French Pouvoir hydrogene


7/11

Calculating pH

pH is the negative of the log10of the hydronium ion

concentration

pH = -log[H3O+]

pOH = -log[OH-]

pH + pOH = 14

Calculate the pH of a 1.0 x 10-3M solution of HCl

Calculate the pH of a 1.0 x 10-3M solution of NaOH

Calculating Concentration

FROM pH Whats the concentration of a solution of

HNO3whose pH is 5.0?

Whats the concentration of a solution of

KOH whose pH is 12.4?

Whats the concentration of a solution ofHI whose pH is 3.67?

pH Indicators

Acid-base indicators

HIn H+ + In-

In acidic solution, what will happen?

(think of equilibrium principles)

In basic solution, what will happen?


8/11

pH Indicators

Each indicator has a range of values it willchange over - __________________

Universal indicators

Neutralization Reactions

Strong acid and strong base

neutralization

What happens when we add HCl andNaOH?

Neutralization reaction of hydronium

and hydroxide ions to form water

molecules

Also produces ___________ -

Titrations Experimental

Neutralization Reactions

Add 200mL of 0.1M HCl to 200mL 0.1M

NaOH and what happens?

What should the resulting pH be?

Equivalence point

End point


9/11

Titration

Curve

Strong

acid/strongbase

Neutralizes

at

equivalence

point

Weak

Acid/Strong

Base

Basic at

equivalence

point

Which Indicator to Use?

Bromthymol blue range of 6.0 7.6; used

for:

Methyl orange range of 3.1 4.4; used for:

Phenolphthalein range of 8.3 10.0; used

for:

Litmus??


10/11

Molarity and Titrations

To determine an unknown solutionsconcentration, a standard solution is

used

20.0mL of 0.005M NaOH is required

to reach the end point of 10.0mL ofHCl. What is the concentration of

HCl?

Steps to Problem Solving

Balanced equation for neutralization reaction;

determine mole ratio

Determine moles of acid or base from known solution

used during titration

Determine moles of solute of the unknown solution

used during titration

Determine molarity of the unknown from the volume

given.

27.4 mL of 0.0154M NaOH is used to

neutralize 20.0mL of HCl. What is the

concentration of the HCl?

27.4 mL of 0.0154M Ba(OH)2is used to

neutralize 20.0mL of HCl. What is the

concentration of HCl?


11/11

Salt Hydrolysis

Anions of dissociated salt accept hydrogen ions

Cations of dissociated salt donate hydrogen ions

What happens when potassium fluoride is

dissolved in water?

What happens when ammonium chloridedissolves in water?

What will the pH be of the following

salts? (7, above, below)

Rubidium nitrite?

Copper(II) sulfate?

Ammonium perchlorate?

Lithium carbonate?

Potassium iodide?

Buffered Solutions

Buffers

Mixture of a weak acid and conjugate

base or a weak base and a conjugate

acid

Buffer capacity

Buffer Calculations

If 200mL of 0.1M HF is added to 200mL of

NaF, what is the pH? (Kafor HF = 6.3 x 10-4)

Blood buffers

CO2(g) + H2O(l) H2CO3(aq) H+(aq) + HCO3

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Acids and Bases Student 10