Chapter 6: Sports Drink

Sports Drinks

This chapter will introduce the chemistry needed to understand how Sports Drinks workSection 6.1: Solutions & electrolytesSection 6.2: Concentrations of solutionsSection 6.3: Acidity & pHSection 6.4: Solubility & precipitatesSection 6.5: StoichiometrySection 6.7: Limiting ReactantsSection 6.6: Properties of solutions

Section 6.1—Solutions & Electrolytes

What are those “electrolytes” they say you’re replacing by drinking sports drinks?

Dissolving substances

Substances are dissolved by a process called hydration when the solvent is waterThe solvent and solute need to break

intermolecular forces within themselves- This requires ENERGY (ENDOTHERMIC)

New intermolecular forces are formed between the solvent and solute.- This releases ENERGY(EXOTHERMIC)

The solvent “carries off” the solute particles

Solution FormationEndothermic

Endothermic

Exothermic

Dissolving Ionic Compounds

- +

+

+

+

-

--

-

+

-

OH H - +Solvent,water

Solute,Ionic compound

Water molecules are polar and they are attracted to the charges of the ions in an ionic compound.

When the intermolecular forces are stronger between the water and the ion than the intramolecular forces between the ions, the water carries away the ion.

- +

+

-

--

-

+

+

Dissolving Ionic Compounds

+

-

OH H - +water

Ionic compound

As more ions are “exposed” to the water after the outer ions were “carried off”, more ions can be “carried off” as well.

Dissolving Ionic Compounds

+

-

OH H - +water

Ionic compound

- +

+

+

+

-

--

-

These free-floating ions in the solution allow electricity to be conducted

Electrolytes

When there are free-floating charges in a solution then it can conduct electricity.

Things that produce free-floating charges when dissolved in water are called electrolytes.

Dissolving Covalent Compounds

- +

- +

- + - +- +

Solvent, water (polar)

+

-

- + Solute, sugar (polar)

Polar covalent molecules are formed in the same way—water forms intermolecular forces with the solute and “carries” the solute particles away.

Dissolving Covalent Compounds

Solvent, water (polar)

+

-

- + Solute, sugar (polar)

- +

- +

- +- + - +

However, the polar covalent molecules stay together and just separates from other solute molecules. NO charged ions form.

Non-electrolytes

When molecules separate from other molecules, but free-floating charges are not produced, the solution cannot conduct electricity.

These are called

non-electrolytes

Types of Electrolytes

Strong Electrolytes

SolubleIonic compounds

Strong Acids & Bases

Weak Electrolytes

InsolubleIonic Compounds

Weak Acids & Bases

Non-Electrolytes

Covalent Compounds except for ACIDS & BASES

Almost all ions are separated when

dissolved in water.

Only a few ions are separated when

dissolved in water

No molecules separate—ions are

not formed

Easily conducts electricity when

dissolved in water

Conducts electricity slightly when

dissolved in water

Does not conduct electricity at all when

dissolved in water

Breaking up Electrolytes

Leave polyatomic ions in-tact (including the subscript within the polyatomic ion)

All subscripts not within a polyatomic ion become coefficients

Be sure to include charges on the dissociated ions!

Example:Break up the following ionic

compounds into their ions

KNO3

Ca(NO3)2

Na2CO3

Breaking up Electrolytes

Leave polyatomic ions in-tact (including the subscript within the polyatomic ion)

All subscripts not within a polyatomic ion become coefficients

Be sure to include charges on the dissociated ions!

Example:Break up the following ionic

compounds into their ions

KNO3

Ca(NO3)2

Na2CO3

K+1 + NO3-1

Ca+2 + 2 NO3-1

2 Na+1 + CO3-2

Misconceptions about dissolving

People often describe something that dissolves as having “disappeared”

Before the solute dissolves, it’s in such a large group of particles that we can see it.

After dissolving, the solute particles are still there—they’re just spread out throughout the solution and are in groupings so small that our eyes can’t see them

Types of Solutions

SOLID-LIQUID

Salt Water

LIQUID-SOLID

Dental Filling (Mercury in Silver)

GAS-LIQUID

SODA(Carbon dioxide gas

in water)

When 2 substances dissolve in one another, they are considered SOLUBLEIf they cannot dissolve in one another, they are INSOLUBLE

A solution is made of two parts:SOLUTE: the substance that is dissolved; usually in minoritySOLVENT: The substance that does the dissolving, usually in majority

Types of Solutions

SOLID-SOLID

ALLOYS(brass, bronze,

sterling silver, steel)

LIQUID-LIQUID

Alcohol & waterAcetic acid in water(vinegar)

GAS-GAS

AIR(Oxygen in Nitrogen

gas)

When 2 liquids dissolve in one another, they are considered MISCIBLEIf they cannot dissolve in one another, they are IMMISCIBLE.

Types of Solutions

Unsaturated

Not full- we can add solute to the solvent

& it will dissolveVisual-no solid on

bottom

Saturated

It’s “Full”- no more solute can be

dissolvedVisual- solid can be seen at the bottom

Super-Saturated

Has more solute dissolved than a

saturated solution has at room temperature

No visual- need some background

information

Diagrams of Unsaturated,Saturated, & SuperSaturated Solutions

Diagrams of Unsaturated vs Saturated Solutions

A SUPERSATURATED SOLUTION

A supersaturated solution can be seeded. This is a solution at room temperature that has beyond the maximum amount of solid it can dissolve.

A SUPERSATURATED SOLUTION

Crystallization Begins.

A SUPERSATURATED SOLUTION

Crystallization Continues.

A SUPERSATURATED SOLUTION

A SuperSautrated solution is now saturated. This is also very exothermic!

Solubility of a Gas vs LiquidIn general,

• the higher the temperature of a solution, more solid can be dissolved.

• the higher the temperature of a solution, less gas can dissolve. Thermal Pollution!

Solubility of Gas vs Liquiud

Henry’s Law

As the pressure above a liquid increases, the solubility of a gas within a liquid will increase

Reading a Solubility CurveFind the data point on the graph of the temperature and solubility of solute in solvent.•If it is below the line, it is UNSATURATED•IF it is on the line, it is SATURATED•If it is above the line, the difference between the point and the line is the extra amount that is sitting at the bottom.

Reading a Solubility CurveExamples1.What kind of solution occurs when 40g of KCl is dissolved in 100 g H2O at 60ºC?

2.What kind of solution occurs when 40g of KCl is dissolved in 100 g H2O at 40ºC? 3.What is the maximum amount of NaBr that can be dissolved in 100 g H2O at 60ºC?

unsaturated

saturated

120 g

Reading a Solubility CurveExamples4. What is the maximum amount of KNO3 that can be dissolved at 70ºC? 5. According to the diamond mark, How much of the KNO3 has been added to the water at 70ºC?

6. How much extra KNO3 is sitting at the bottom of the container at this temperature of 70ºC?

140g

160g

20g

Factors that Affect the Rate of Hydration1. Temperature2. Particle Size3. Agitation (stirring)

Section 6.2—Concentration

How do we indicate how much of the electrolytes are in the drink?

ConcentrationA measure of the amount of solute in a given

amount of solutionQualitative Description:

Dilute: small amount of solute compared to solvent

Concentrated: large amount of solute compared to solvent

Concentrated Dilute

Concentrated versus Dilute

solute solvent

Lower concentration

Not as many solute (what’s being dissolved) particles

Higher concentration

More solute (what’s being dissolved) particles

Molarity: a quantitiative description of concentrationMolarity (M) is a concentration unit that uses moles

of the solute instead of the mass of the solute

2M solution is 2 moles of solute dissolved in 1.0 L of solution

solutionL

solutemolesM

moles

Molarity Liters X

Molarity ExampleExample:

If you dissolve 5.0 moles of NaCl in

300.0 mL of water, what is the molarity?

Molarity Example

L

molesM

300.0

0.5

Example:If you dissolve 5.0 moles of NaCl in

300.0 mL of water, what is the molarity?

solventL

solutemolesM 17 M NaCl

Remember to change mL to L! 300. mL of water = 0.300 L

Molarity Example

Example:If you dissolve 12 g of NaCl in 150 mL of water, what is

the molarity?

Molarity Example

L

molesM

150.0

21.0

Example:If you dissolve 12 g of NaCl in 150 mL of water, what is

the molarity?

solventL

solutemolesM 1.4 M NaCl

12 g NaCl = _______ mole NaClg NaCl

mole NaCl1

58.44

0.21

1 mole NaCl molecules = 58.44 g

NaCl

11

22.99 g/mole35.45 g/mole

= 22.99 g/mole= 35.45 g/mole+

58.44 g/mole

Remember to change mL to L! 150 mL of water = 0.150 L

Molarity ExampleExample:

How many grams of CaCl2 would be needed to make

25.0 ml of a 2.5M solution?

Molarity Example

L

XmolesM

0250.5.2

Example:How many grams of CaCl2 would be needed to make

25.0 ml of a 2.5M solution?

solventL

solutemolesM .0625 moles NaCl

.063 mol CaCl2 = 6.9 grams CaCl2

CaCl2

g CaCl2 110.98

1 mol

1 mole CaCl2 = 110.98 g

CaCl

12

40.01 g/mole35.45 g/mole

= 40.08 g/mole= 70.90 g/mole+

110.98 g/mole

Remember to change mL to L! 25 mL of water = 0.025 L

How to Make a Solution Make 500.0 ml of a .12 M solution of CoCl22H2O

1st: Convert your moles of solute to grams.

.12 M x .500L = .060 moles solute

.060 moles x 165.87 g/1mol = 9.948 g

(10. g) 2nd : Add solute amount to a

volumetric flask.

Add 10.0 g cobalt chloride to flask

3rd : Add enough solvent to make the required amount of solution and stir.

In this case, the solvent is ethanol. Add slowly until 500 ml of solution is reached.

What Not to Do!

Never add the solvent first!Never add the solvent first!

Dilution: A technique used to make a dilute solution from a Concentrated Solution

= .0050 mol .10 L

= .050 M I2

= .0050 mol .50 L

= .010 M I2

How to Calculate a Dilution

M1V1= M2V2

moles1 = moles2

M1V1 = original (stock) concentration &

volumeM2V2 = new concentration & volume

You do not have to change your volume to liters!

Example:

What is the molarity of a new solution if you diluted 100.0 ml of 3.0M HCl to 250.0 ml?

Example:What is the molarity of a new solution if you

diluted 100.0 ml of 3.0 M HCl to 250.0 ml?

M1V1= M2V2

(3.0M)(100.0ml) = (X)(250.0 ml)

300.0 Mml= 250.0ml x

250.0 ml 250.0ml

X= 1.2 M

Section 6.3—Acidity, pH

How does concentration of acid affect the pH of a sports drink?

Review of Acids – Arrhenius Definition

Acids produce Hydronium ion (H3O+1) in water

Hydronium ion is water + a hydrogen cation

H

OH

water

H+1

H

OH

H +1

Bases – Arrhenius Definition

Bases produce the hydroxide ion in water

HO-1

Hydroxide Ion

A new of definition of an ACID: According to Bronsted-Lowry

An acid is a hydrogen (proton) donor

The substance that remains after the hydrogen has been donated is called the conjugate base

Example: NH3 + H2O OH- + NH4+

acid conjugate base

A new of definition of a BASE: According to Bronsted-Lowry

A base is a hydrogen (proton) acceptor

The substance that forms after the hydrogen has been accepted is called the conjugate acid

Example: NH3 + H2O OH- + NH4+

base conjugate acid

Conjugate Acid-Base Pairs

ACIDS & BASES WILL ALWAYS BE ON THE REACTANT SIDE

CONJUGATE ACIDS & BASES WILL ALWAYS BE ON THE PRODUCT SIDE

Practice Problems: Label the acid & base on the left side of the reaction and the conjugate acid & conjugate base on the right side.

a) HCl + H2O H3O+ + Cl−

______ ______ ______ ______

b) HCO3-1 + H2O H2CO3 + OH−

_____ ______ ______ ______

acid base C.A. C.B.

base acid C.A. C.B.

Characteristics of Acids & BasesBasesAcids

Produce H3O+1 (hydronium ion) in water

Produce OH-1 (hydroxide ion) in water

Tastes sour Tastes Bitter

React with active metals to form hydrogen gas

Feels slippery

Turns red litmus blueTurns pink in phenlphthalien

Turns blue litmus redTurns clear in phenolphthalien

React with bases to form salt and water (neutralization

reaction)

React with acids to form salt and water (neutralization

reaction)

Both are considered electrolytes

Strength versus Concentration

Strong versus Weak Acids

+

++

-

-

-

In a Strong acidMost of the acid molecules

have donated the H+1 to water

How many hydronium ion – anion pairs can you find?

How many intact acid molecules can you find?

3

1

Strong versus Weak Acids

+

-

In a Weak acidOnly a few of the acid

molecules have donated the H+1 to water

How many hydronium ion – anion pairs can you find?

How many intact acid molecules can you find?

1

3

Acids and Bases as Electrolytes

Acids and bases dissociate into ions in water

Free-floating ions in water conduct electricity

Acids & Bases are electrolytes

Strong acids and bases are strong electrolytesWeak acids and bases are weak electrolytes

Calculating pH

Is a measure the acidity of a sample

pH Scale

0 14

Highly acidic Very basic (not acidic)

neutral

7

Acids have a pH that are less than 7.0Bases have pH values that are more than 7.0Neutral is considered a pH of 7.0

less acidic, more basic

more acidic, less basic

Calculating pH

pH scale – Logarithmic scale of the acidity of a solution

The pH scale uses base “10”

]log[ 13

OHpH

pHOH 10][ 13

pH has no units

[ ] = concentration in Molarity

The formula for calculating pH

The formula for calculating hydronium ion concentration

The “-” in the pH equation

Concentration of Hydronium ion versus pH

0

0.5

1

0 0.5 1 1.5 2

pH

[H3

O+

]

Because pH is the negative log of concentration of hydronium, as concentration increases, the pH goes down.

The lowest pH is the highest concentration of hydronium ion

What does a “log” scale really mean?

pH

4

3

2

1

10x more acidic

100x more acidic

1000x more acidic

Leve

l of

acid

ity in

crea

ses

Every change of 1 in pH shows a change of 10x in concentration of hydronium

Example

The pH of a solution changes from a pH of 5 to a pH of 3.

a.Did it increase or decrease in hydrogen ion concentration?

b.By what factor did it change?

Example 2 :Calculating pH

Example:Find the pH if the

concentration of [H3O+1] is 1.0x 10-8 M

An example of calculating pH

pH = 8.00

]log[ 13

OHpH

)80.1log( epH

Example:Find the pH if the concentration of

[H3O+1] is 1.0 x 10-8 M

Example 3; Calculating hydronium concentration ([H3O+1])

Example:Find the [H3O+1] if

the pH is 5.0

An example of calculating hydronium

H3O+1 = 1 x 10-5 M

pHOH 10][ 13

513 10][ OH

Example:Find the [H3O+1] if

the pH is 5.0

Auto-ionization of Water

Water molecules collide spontaneously and will split into ions. This is called auto-ionization

H2O + H2O H3O+1 + OH-1

At 25°C the following is true:

[H3O+1] × [OH-1] = 1.0 × 10-14 M2

Hydrogen Ion Concentration ValuesIf the hydrogen ion concentration is greater than

hydroxide ion, the solution is ACIDIC with a pH < 7[H+] > [OH-] or[H+] > 1.0 x 10-7 M

If the hydrogen ion concentration is less than hydroxide ion, the solution is BASIC with a pH > 7[H+] < [OH-] or[H+] < 1.0 x 10-7 M

If the hydrogen ion concentration is equal to hydroxide ion, the solution is NEUTRAL with a pH = 7[H+] = [OH-] = 1.0 x 10-7 M

Calculating pOH

]log[ 1 OHpOH

pOHOH 10][ 1

[ ] = concentration in Molarity

The formula for calculating pOH

The formula for calculating hydroxide ion concentration

To relate pH and pOH 14 pHpOH

Let’s Practice #1

Example:Find the pOH if the

concentration of [OH-1] is 1.0 × 10-5 M

Let’s Practice #1

pOH = 5.00

Example:Find the pOH if the

concentration of [OH-

1] is 1.0 × 10-5 M

Let’s Practice # 2

Example:Find the pOH if

the pH is 4.

Let’s Practice #2

Example:Find the pOH if

the pH is 4.

pOH= 10

144 pOH

Let’s Practice #3

Example:Find the [OH-1] if the

[H+] is 1.0 x10-9M

Let’s Practice #3: 2 ways to do this…1st way

14113 101][][ OHOH

1419 101][]100.1[ OH

Example:Find the [OH-1] if

the [H+] is 1.0 x10-9

]100.1[

101][

9

141

OH

[OH-] = 1.0 x10-5 M

Let’s Practice #3: 2 ways to do this…2nd way

Example:Find the [OH-1] if

the [H+] is 1.0 x10-9

[OH-] = 1.0 x10-5 M

]log[ 13

OHpH

14 pHpOHpH = 9.00

pOH + 9.00 = 14

pOH = 5.00

pOHOH 10][ 1

Let’s Practice #4

Example:What is the pH if the

concentration of [OH-] = 1.0 x 10-7M

Let’s Practice #4

pOH = 7

Example:What is the pH if the

concentration of [OH-] = 1.0 x 10-7

]log[ 1 OHpOH

]100.1log[ 7 xpOH

14 pHpOH

147 pH

pH = 7