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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.
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