Unit 9 Solutions, Acids & Bases What is a solution? Solution – a mixture where the components are uniformly intermingled. Homogeneous Solutions are

Unit 9Unit 9

Solutions, Acids & BasesSolutions, Acids & Bases

What is a solution?What is a solution?

Solution – a mixture where the components are uniformly intermingled. Homogeneous

Solutions are made up of a solvent and solute.• Solute – substance that is dissolved• Solvent – substance in which materials

are dissolved in. The medium in which the solute is dissolved in.

Solution CompositionSolution Composition

The solubility of a solute is limited. • Saturated solution – contains as much

solute as will dissolve at that temperature • Unsaturated solution – has not reached

the limit of solute that will dissolve • Oversaturated solution – contains too

much solute in which the rest of solute remains on the bottom

Supersaturated solution – occurs when a solution is saturated at an elevated temperature and then allowed to cool but all of the solid remains dissolved

• Contains more dissolved solid than a saturated solution at that temperature

• Unstable – adding a crystal causes precipitation

• Amounts of substances can vary in different solutions. –Specify the amounts of solvent and

solutes –Qualitative measures of concentration

• concentrated – relatively large amount of solute

• dilute – relatively small amount of solute

B. Solution Composition: An Introduction


Which solution is more concentrated?



Which solution is more concentrated?

C. Factors Affecting the Rate of Dissolving

C. Factors Affecting the Rate of Dissolving

Surface area Stirring Temperature

Solubility CurvesSolubility Curves

Graphs that illustrates how much of solute will dissolve at any given temperature.

Solubility ChartSolubility Chart

QuestionsQuestions

How many grams of KClO3 is diluted in water at 90 degrees?

How many grams of K2Cr2O7 is diluted in water at 60 degrees?

How many grams of Pb(NO3)2 is diluted in water at 10 degrees?

70g of CaCl2 will dissolve at what temperature to form a saturated solution? 40g of NaCl will dissolve at what temperature to form a saturated solution? 90g of KNO3 will dissolve at what temperature to form a saturated solution?

At 30 degrees, you dissolve 25 grams of KNO3 in water. How much more KNO3 can you add to make it a saturated solution?

At 10 degrees, you dissolve 25 grams of NaNO3 in water. How much more NaNO3 can you add to make it a saturated solution?

At 90 degrees, you dissolve 10 grams of KClO3 in water. How much more KClO3 can you add to make it a saturated solution?

Which salt has solubility values that are least affected by temperature? At 75 degrees, I attempted to dissolve 50g of KCl. Is this a saturated, unsaturated, or

supersaturated solution? At 40 degrees, I attempted to dissolve 50g of NaCl. Is this a saturated, unsaturated, or

supersaturated solution? At 55 degrees, I attempted to dissolve 50g of Pb(NO3)2. Is this a saturated, unsaturated,

or supersaturated solution?

B. Solution Composition: Molarity


Concentration of a solution is the amount of solute in a given volume of solution.



Consider both the amount of solute and the volume to find concentration.

Example ProblemExample Problem

What is the concentration (or Molarity) of a solution that contains 432 mole NaCl in 3.0 L of water?

144M


What is the concentration of a solution that contains 11.2g of LiCl in a 0.50L solution?• Make sure that you convert the grams

to moles before you find the molarity.

First, convert the grams to moles.

11.2g LiCl 1 mol LiCl

42.39g LiCl= 0.264 mol LiCl

Use the moles to find the molarity.

0.264𝑚𝑜𝑙 𝐿𝑖𝐶𝑙0.50𝐿 = 0.53M



To find the moles of solute in a given volume of solution of known molarity use the definition of molarity.

How many grams of HCl was mixed into a 3L of a 9M solution?

Remember that:𝑚𝑜𝑙𝑠𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒𝐿𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛

=𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛(𝑀 )


What do we know?• Concentration = 9M• L of solution = 3• Mols of solute = ?

𝑚𝑜𝑙𝑠𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒𝐿𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛



𝑚𝑜𝑙𝑠𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒𝐿𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛


𝑚𝑜𝑙𝑠𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒3𝐿

=9𝑀

Solve for the moles of solute

How many grams of HCl was mixed into a 3L of a 9M solution?𝑚𝑜𝑙𝑠𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒

3𝐿=9𝑀

Mols of solute = (9M)(3L) = 27 mols of HCl

You need to convert the mols of HCl to grams of HCl.

27 mols HCl

1 mol HCl

34.46g HCl= 930.42g HCl

Practice ProblemsPractice Problems

1. Calculate the molarity of a solution prepared by dissolving 11.5g of solid NaOH in enough water to make 1.50L of solution.

2. 2. Calculate the molarity of a solution prepared by dissolving 1.56g of gaseous HCl into enough water to make 0.0268L of solution.


3. What is the volume of a 3.2M solution of H2SO4 in a 0.30 L beaker?

4. What is the mass (g) of a 1.2M solution of CaCO3 in a 0.50 L flask?

Dilution Dilution

Water can be added to an aqueous solution to dilute the solution to a lower concentration.

Only water is added in the dilution – the amount of solute is the same in both the original and final solution.

D. Dilution D. Dilution

Diluting a solution • Transfer a measured amount of

original solution to a flask containing some water.

• Add water to the flask to the mark (with swirling) and mix by inverting the flask.

D. DilutionD. Dilution

We can use a simple equation can be used in order to correctly dilute a solution to any concentration

M1V1 = M2V2

M1 = the molarity of the initial solution

V1 = volume of the initial solution

M2 = the molarity of the diluted solution

V2 = volume of the diluted solution


1. Suppose we want to prepare 500. mL of 1.00 M acetic acid, HC2H3O2, from a 17.5M stock solution of acetic acid. What volume of the stock solution is required?

M1 = 17.5MV1 = ?M2 = 1.00MV2 = 500 mL

M1V1 = M2V2

(17.5)V1 = (1.00)(500)

V1 = = 28.6mL


1. What volume of 16M sulfuric acid must be used to prepare 1.5L of a 0.10M H2SO4 solution?

2. What is the concentration when you dilute 0.3L of 10M of HCl in to a .500L solution?

3. What is the concentration of a 250mL solution that was used to make a 600mL solution of 2.5M of NaCl?

6M

6M

I. Introduction toAcids & Bases

I. Introduction toAcids & Bases

Acids & BasesAcids & Bases

A. PropertiesA. Properties

electrolytes electrolytes

turn litmus red

sour taste

react with metals to form H2 gas

slippery feel

turn litmus blue

bitter taste

ChemASAP

vinegar, milk, soda, apples, citrus fruits

ammonia, lye, antacid, baking soda

Acids(Svante Arrhenius’ Definition)

Acids(Svante Arrhenius’ Definition)

Acids form hydrogen ions or hydronium ions when dissolved in water H+ H3O+

B. DefinitionsB. Definitions

Arrhenius - In aqueous solution…

HCl + H2O H3O+ + Cl–

• Acids form hydronium ions (H3O+)

H

HH H H

H

ClClO O

–+

acid

Common AcidsCommon Acids

HCl Hydrochloric

H2SO4 Sulfuric

HNO3 Nitric

H3PO4 Phosphoric

H2CO3 Carbonic

Acid NomenclatureAcid Nomenclature

Binary Compound – compound consisting of 2 elements.

An acid binary compound consists of 2 elements in which one of them is ALWAYS hydrogen. • HF• HCl• HBr


To name acid binary compounds• Add hydro- as a prefix• Use the root of the element and add –

ic acid as a suffix


HF• Hydrofluoric acid

HCl• Hydrochloric acid

H2S

• Hydrosulfuric acidH3P

• Hydrophosphuric acid


Writing the name from chemical formulas• Figure out the charge of the anion

• Hydrobromic acid – H+ and Br- • Br has a negative 1 charge

• Add enough H+ until the compound is neutral


Hydronitric acid• H3N

Hydrofluoric acid• HF

Hydroselenic acid• H2Se


Acid polyatomic compounds

Remember polyatomic compounds are compounds that have a charge.

When naming polyatomic acids…• DO NOT USE HYDRO- as preffix• Use either –ic acid or –ous acid


ate—ic / ite—ous Rule• If the polyatomic ion ends with an –ate

replace it with an –ic acid • H2SO4 – SO4 is sulfate

H2SO4 – Sulfuric acid

Add –ic


ate—ic / ite—ous Rule• If the polyatomic ion ends with an –ite

then replace it with an –ous acid• HNO2 – NO2 is nitrite

HNO2 – Nitrous acid

Add -ous

Example ProblemsExample Problems

1. H2SO3

2. H3PO4

3. HClO2

4. HC2H3O2

5. H2Cr2O7

6. H2CO3

7. HNO2

Sulfurous acid

Phosphoric acid

Chlorous acid

Acetic acid

Dichromic acid

Carbonic acid

Nitrous acid


Writing the name from chemical formulas• Figure out the charge of the

polyatomic ion• Sulfuric acid – H+ and SO4

-2

• SO4 has a negative 2 charge

• Add enough H+ until the compound is neutral• H2SO4


1. Hypochlorous acid

2. Perchloric acid

3. Nitric acid

4. Permanganic acid

5. Sulfurous acid

HClO

HClO4

HNO3

HMnO4

H2SO3

More Example ProblemsMore Example Problems

1. HF

2. Hydrochloric acid

3. H2Se

4. Chromic acid

5. HClO3

6. Chlorous acid

7. HNO3

8. H3N

Hydrofluoric acidHCl

Hydroselenic acid

H2CrO4

Chloric acid

HClO2

Nitric acid

Hydronitric acid

Bases (Arrhenius’ Definition)Bases (Arrhenius’ Definition)

Bases form hydroxide ions when dissolved in water

OH-


Arrhenius - In aqueous solution…

• Bases form hydroxide ions (OH-)

NH3 + H2O NH4+ + OH-

H

H

HH H

H

N NO O–+

H

H

H H

base

Common BasesCommon Bases

NaOH Sodium Hydroxide

NH4OH Ammonium Hydroxide

Ca(OH)2 Calcium Hydroxide


Brønsted-Lowry

HCl + H2O Cl– + H3O+

• Acids are proton (H+) donors. • Bases are proton (H+) acceptors.

conjugate acidconjugate base

baseacid


H2O + HNO3 H3O+ + NO3–

CBCAAB


Amphoteric - can be an acid or a base.

NH3 + H2O NH4+ + OH-

CA CBB A


F -

H2PO4-

H2O

HF

H3PO4

H3O+

Give the conjugate base for each of the following:

Polyprotic - an acid with more than one H+


Br -

HSO4-

CO32-

HBr

H2SO4

HCO3-

Give the conjugate acid for each of the following:

C. StrengthC. Strength

Strong Acid/Base• 100% ionized in water• strong electrolyte

- +

HCl

HNO3

H2SO4

HBr

HI

HClO4

NaOH

KOH

Ca(OH)2

Ba(OH)2

C. StrengthC. Strength

Weak Acid/Base• does not ionize completely• weak electrolyte

- +

HF

CH3COOH

H3PO4

H2CO3

HCN

NH3

pH pH

A. Ionization of WaterA. Ionization of Water

H2O + H2O H3O+ + OH-

Kw = [H3O+][OH-] = 1.0 10-

14

At any one time water solution contains hydronium and hydroxide ions.

A. Ionization of WaterA. Ionization of Water

Find the hydroxide ion concentration of 3.0 10-2 M HCl.

[H3O+][OH-] = 1.0 10-14

[3.0 10-2][OH-] = 1.0 10-14

[OH-] = 3.3 10-13 M

Acidic or basic?Acidic

pH = -log[H3O+]

B. pH ScaleB. pH Scale

0

7INCREASING

ACIDITY NEUTRALINCREASING

BASICITY

14

pouvoir hydrogène (Fr.)“hydrogen power”


pH of Common SubstancespH of Common Substances


pH = -log[H3O+]

pOH = -log[OH-]

pH + pOH = 14

Important Equations

pH = -log[H3O+]

pOH = -log[OH-]

pH + pOH = 14

[H3O+] = concentration of the acid

[OH-] = concentration of the base

The pH of sea water is about 7.8. What is the pOH?

What do we know?pH = 7.8

What are we trying to figure out?

pOH = ?

What equation should we use?

pH + pOH = 14

The pH of sea water is about 7.8. What is the pOH?

pH + pOH = 14

7.8 + pOH = 14 Solve for pOH

pOH = 14 – 7.8 Calculate

6.2


What is the pH of 0.050 M HNO3?

pH = -log[H3O+]

pH = -log[0.050]

pH = 1.3

Acidic or basic?Acidic


What is the molarity of HBr in a solution that has a pOH of 9.6?

pH + pOH = 14

pH + 9.6 = 14

pH = 4.4

Acidic

pH = -log[H3O+]

4.4 = -log[H3O+]

-4.4 = log[H3O+]

[H3O+] = 4.0 10-5 M HBr


1. What is the pH of a substance that has a pOH of 10.3?

2. What is the concentration of an acid that has the pH of 4.3?

3. What is the concentration of a base that has the pH of 8.9?

4. What is the pH of an substance with the [H3O+] concentration of 5.0 x 10-5 M?

5. What is the pOH of a substance with the [H3O+] concentration of 4.2 x 10-13?

3.7

5.0 x 10-5 M

7.9 x 10-6 M

4.3

1.6

TitrationsTitrations

A. NeutralizationA. Neutralization

Chemical reaction between an acid and a base.

Products are a salt (ionic compound) and water.

A. NeutralizationA. Neutralization

ACID + BASE SALT + WATER

HCl + NaOH NaCl + H2O

HC2H3O2 + NaOH NaC2H3O2 + H2O

• Salts can be neutral, acidic, or basic.• Neutralization does not mean pH = 7.

weak

strong strong

strong

neutral

basic

B. TitrationB. Titration

Titration• Analytical method

in which a standard solution is used to determine the concentration of an unknown solution.

standard solution

unknown solution

Equivalence point (endpoint)• Point at which equal amounts

of H3O+ and OH- have been added.

• Determined by…• indicator color change

B. TitrationB. Titration

• dramatic change in pH

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Unit 9 Solutions, Acids & Bases What is a solution? Solution – a mixture where the components are uniformly intermingled. Homogeneous Solutions are