Chapter 6: Sports Drink

Introductory Activity

What do you think are the benefits of drinking a sports drink while exercising rather than plain water?

How are your ideas influenced by the marketing strategies of the companies that sell these drinks?

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

Sports Drinks

SolutionSolution

Is a

ElectrolytesElectrolytes

SolubilitySolubility

With

that need to all dissolve when mixed together

ConcentrationsConcentrations

How much solute is in it?

pHpH

Some affect

TitrationsTitrations

Can be determined by

Differ from pure liquids in PropertiesProperties

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 hydrationThe solvent and solute need to break

intermolecular forces within themselvesNew intermolecular forces are formed between

the solvent and soluteThe solvent “carries off” the solute particles

Dissolving Ionic Compounds

- +

+

+

+

-

--

-

+

-

OH H - +water

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 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 themselves do not split into charged ions—the solute molecule stays together and just separates from other solute molecules.

Non-electrolytes

When molecules separate from other molecules (breaking intermolecular forces), but free-floating charges are not produced from breaking intramolecular forces, the solution cannot conduct electricity.

These are called non-electrolytes

Types of Electrolytes

Strong Electrolytes

Ionic compounds

Weak Electrolytes

Ionic Compounds

Non-Electrolytes

Covalent Compounds

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

Unsaturated

More solute can be dissolved

Saturated

No more solute can be dissolved—it’s

“full”

Super-Saturated

Has more solute than would make a saturated solution

dissolved

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