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 work Section 6.1: Solutions & electrolytes Section 6.2: Concentrations of solutions Section 6.3: Acidity & pH Section 6.4: Solubility & precipitates Section 6.5: Stoichiometry Section 6.7: Limiting Reactants Section 6.6: Properties of solutions

Sports Drinks Properties Solution Concentrations Electrolytes pH Is a Properties Differ from pure liquids in Solution How much solute is in it? With Concentrations Electrolytes Some affect Can be determined by that need to all dissolve when mixed together pH Solubility Titrations

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 The solvent and solute need to break intermolecular forces within themselves New intermolecular forces are formed between the solvent and solute The solvent “carries off” the solute particles

Dissolving Ionic Compounds + - O H - + Ionic compound water 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 + - O H - + Ionic compound water - 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 + - O H - + Ionic compound water + - 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 Weak Electrolytes Non-Electrolytes Ionic compounds Ionic Compounds 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 Saturated Super-Saturated More solute can be dissolved No more solute can be dissolved—it’s “full” Has more solute than would make a saturated solution dissolved In general, the higher the temperature of a solution, more solid can be dissolved.