Chapter 6: Solutions and Other Mixtures • A mixture is a combination of several substances that do not form a chemical reaction and can be separated into their individual parts.
• An example is this classroom. It is a mixture of boys, girls, age, ethnicity, etc. that could be physically separated.

Chapter 6: Solutions and Other Mixtures • Heterogeneous mixtures are unevenly combined.
• The composition of these mixtures vary throughout the sample.
• If you have a box of Fruity Pebbles, you can separated it by size, color, shape etc. It is unevenly mixed.

Chapter 6: Solutions and Other Mixtures • Many heterogeneous solutions are suspensions. Italian dressing, sand and water, some orange juices are examples.
• When agitated (stirred or shaken) everything mixes evenly, but if left alone, it settles into layers.

Chapter 6: Solutions and Other Mixtures • The heavier (denser) the particle, the faster it settles.
• If the particles are smaller, they often do not settle into layers, but remain dispersed in another substance. These are called colloids or colloidal suspensions.

Chapter 6: Solutions and Other Mixtures • An example is Jell-O. The particles are so small they do not settle out, but remain spread out.
• Paint is made of tiny particles of pigment (colored) solids suspended in a liquid.
• Blood is another example. It is made of many different types of solids.

Chapter 6: Solutions and Other Mixtures • Some liquids form suspensions also. A common example is water and oil.
• If you mix water and oil they do not combine unless you keep shaking them.

Chapter 6: Solutions and Other Mixtures • Often, if care is taken, liquid suspensions can be separated by carefully pouring off the less dense liquid and leaving the denser behind.
• Liquids that cannot be combined are called immiscible.
• Immiscible liquids will eventually separate.

Chapter 6: Solutions and Other Mixtures • This is why Italian dressing needs to be shaken, not stirred before going on a salad and why many other things must be mixed well before being used.

Chapter 6: Solutions and Other Mixtures • Sometimes, immiscible liquids can be forced to combine into an emulsion.
• An emulsion is any mixture of immiscible liquids in which the liquids are spread throughout one another.
• Mayonnaise, cream, butter, are examples.

Chapter 6: Solutions and Other Mixtures • Mayonnaise is a mixture of vinegar and oil emulsified by egg yolk.
• Homemade mayonnaise is easy if done correctly. Add oil to vinegar and egg yolks slowly while whipping constantly. Other seasonings can be added to make unique flavors.

Chapter 6: Solutions and Other Mixtures • Solutions-a homogeneous mixture of two or more substances uniformly spread out.
• Solute-the substance that dissolves, • Solvent-the substance that dissolves the solute to make the solution.

Chapter 6: Solutions and Other Mixtures •
look uniform, but are uniform or evenly mixed.
mixtures not only • Sugar water or salt water are good examples.
• The solids (
) are so small that the liquid (
) keeps the particles constantly moving.

Chapter 6: Solutions and Other Mixtures • According to Kinetic theory, molecules are always moving. As these molecules move, they collide with other molecules and impart some of their energy to those they hit.
• If water molecules hit a sugar molecule, they move that sugar.

Chapter 6: Solutions and Other Mixtures • If the sugar is a large molecule, it takes many repeated hits to dissolve. Thus, the more surface area available, the faster something will dissolve.
• Loose sugar granules will dissolve faster than compact sugar cubes.

Chapter 6: Solutions and Other Mixtures • Stirring a solution adds kinetic energy into the solution. By adding energy, the molecules move faster and collisions occur more often.
• As the collisions occur, they impart energy and speed the rate of dissolving.

Chapter 6: Solutions and Other Mixtures • The more you stir or agitate as solution, the more solute will enter the solution.
•
also affects the solubility rate of a solution. The warmer the solution, the more solute will be dissolved.

Chapter 6: Solutions and Other Mixtures • Concentration is used to state how much solute in grams is dissolved into a given quantity of solvent in grams. grams(solute)/100 grams(solvent) • A dilute solution is a small amount of solute in a large amount of solvent.

Chapter 6: Solutions and Other Mixtures • A concentrated solution is a large quantity of dissolved solute.
• An unsaturated solution can dissolve more solute.
• A saturated solution cannot dissolve any more solute under the current conditions.

Chapter 6: Solutions and Other Mixtures • Pressure affects how much solute can enter a solution.
• Some solutes require high pressure to enter into a solution, some require low pressure. An example that we see everyday is in carbonated beverages.

Chapter 6: Solutions and Other Mixtures • The bubbles are CO
2
molecules that have been dissolved into very cold liquid soda syrup. As the temperature increases, the ability of the syrup to hold the CO
2
in solution decreases. Once the top is removed, the pressure tries to equalize.

Chapter 6: Solutions and Other Mixtures • Water is sometimes called the universal solvent.
• Water is not an ionic compound, but it is polar. This means that it has a slightly positive charge at one end and a slightly negative charge at the other.

Chapter 6: Solutions and Other Mixtures • This polarity helps explain why water can dissolve so many compounds.
• Most substances that dissolve in water have slight charges that line up with water without reacting.

Chapter 6: Solutions and Other Mixtures • Chemists have a saying “like dissolves like” to decide if water will dissolve something.
• A polar molecule like methane will dissolve in water whereas a non-polar molecule like gasoline is immiscible.

Chapter 6: Solutions and Other Mixtures • Gasoline will mix with oil whereas methane will not.
• The partial charges have their own symbols—lower case Greek delta (δ)—to indicates slight charge: positive= δ+ negative= δ-

Chapter 6: Solutions and Other Mixtures • A solution is unsaturated if more solute can be dissolved.
• A saturated solution is in equilibrium. No more solute can be added.

Chapter 6: Solutions and Other Mixtures • Solubility is the greatest quantity of solute that will dissolve in a given amount of solvent to produce a saturated solution.
• If you heat a saturated solution, you can add more solute. As it cools, the excess solute remains in the solution. This is called a supersaturated solution.

Chapter 6: Solutions and Other Mixtures • However, it is often unstable and adding more solute can have impressive affects.
• If you have a supersaturated solution of sodium acetate and add a tiny amount of solute, the sodium acetate drops from solution in a brilliant, crystalline form.

Chapter 6: Solutions and Other Mixtures • STOP HERE FOR 2009. START HERE FOR 20010

Chapter 6: Solutions and Other Mixtures • Dilute, concentrated, unsaturated, saturated, or supersaturated are often not as accurate as you need.

Chapter 6: Solutions and Other Mixtures • Exact amounts of solute in the solvent often needed for many experiments. Molarity is used to figure out precisely the ratio of solute to solvent.
Molarity= moles of solute/liters of solution M= mol/ L

Chapter 6: Solutions and Other Mixtures • A 1.0 M (1 molar) solution of NaCl contains 1.0 mol of dissolved NaCl for every 1.0 L of solution.
• Chemists prefer molarity since it expresses the molar amount of solute present.

Chapter 6: Solutions and Other Mixtures • Acids are substances that donate hydrogen ions to form hydronium ions when dissolved in water.
H
+
+ H
2
O  H
3
O
+
• Bases are substances that either contain OH
-
or react with water to form OH
-
ions.

Chapter 6: Solutions and Other Mixtures • Acids turn blue litmus paper red, bases turn red litmus paper blue. Litmus paper is an pH indicator. pH is the concentration of hydronium ions in the solution.
• Acids taste sour and bases taste bitter.

Chapter 6: Solutions and Other Mixtures • All acids conduct electricity because of hydronium ions.
• Strong acids fully ionize in water. The reaction is one way.
• Weak acids do not fully ionize in water and the reaction goes both ways.

Chapter 6: Solutions and Other Mixtures • Acids and bases can be dangerous.
• All bases conduct electricity because of hydroxide ions.
• Strong bases ionize fully in water. The reaction is one way.
• Weak bases do not fully ionize in water and the reaction goes both ways.

Chapter 6: Solutions and Other Mixtures • Strong acid: HNO
3
+ H
2
O  NO
3 -
+ H
3
O
+ nitric acid water nitrate ion hydronium ion
• Weak acid: CH
3
COOH + H
2
O CH
3
COO
acetic acid water acetate ion
+ H
3
O
+ hydronium ion
• Strong base: KOH  K
+
+ OH
potassium hydroxide potassium ion hydroxide ion
• Weak base: NH
3
+ H
2
O NH
4 +
+ OH
ammonia water ammonium ion hydroxide ion

Chapter 6: Solutions and Other Mixtures • The pH of a solution indicates the concentration of hydronium ions, but it also can indicate the concentration of hydroxide ions.
• Using a pH indicator can tell you if something is an acid, base, or neutral solution.

Chapter 6: Solutions and Other Mixtures • Typically pH ranges from 0 to 14 with neutral being 7.
• Acids range from 0 to 6.9 and bases range from 7.1 to 14.

Chapter 6: Solutions and Other Mixtures • Each whole number unit of pH represents a factor of 10. Thus an acid of 4 is ten times stronger than an acid of 5.
• A universal pH indicator strip will show a color coded pH scale.

Chapter 6: Solutions and Other Mixtures • A neutralization reaction is a reaction between hydronium ions and hydroxide ions to create water molecules. The resulting solution is more neutral than the reactants.

Chapter 6: Solutions and Other Mixtures • Strong acids and bases react to form water and salts.
HCl + H
2
NaOH  Na H
3
O
+
+ Cl
-
O  H
+ 3
O
+
+ Cl
-
+ OH
-
+ Na
+
+ OH
-
 Na
+
+ Cl
-
+ 2H
2
O • The Na
+
and Cl ions reacted.
-
ions did not react, only the hydronium and hydroxide

Chapter 6: Solutions and Other Mixtures • If you excluded the non-reactants, the equation is much simpler: H
3
O
+
+ OH
-
 2H
2
O • Salts are ionic compounds that are often soluble in water.

Chapter 6: Solutions and Other Mixtures • Some acid-base reactions do not neutralize because of pH differences or quantity differences.
• Strong bases/weak acids or strong acids/ weak bases only partially neutralize.
• A strong acid/weak base may have a higher pH and still be acidic. A large quantity of a weak base would be to added to neutralize a strong acid.

Chapter 6: Solutions and Other Mixtures • Because of the reactivity between acids and bases, never combine household cleaners.
• Soaps are emulsifiers. They have glycerol chain (—COO
-
) that is negatively charged that can combine with oils and greases and water.
• They allow immiscible substances to dissolve. This is why soaps clean.

Chapter 6: Solutions and Other Mixtures • Detergents are non-soap water soluble cleaners that remove dirt and oils.
• They have a sulfonate group (—SO
3 -
) that can combine with dirt and oil and water to clean.

Chapter 6: Solutions and Other Mixtures • Ammonia cleaners have ammonia gas dissolved into solution to remove grease and oils.
NH
3
+ H
2
O NH
4 +
+ OH
ammonia water ammonium ion hydroxide ion
• Disinfectants are substances that kill bacteria.

Chapter 6: Solutions and Other Mixtures • Bleach is a solution of sodium chlorite. NaClO
2
, or sodium hypochlorite, NaOCl, in water.
• Antacids are weak bases that neutralize excess stomach acids.
• Shampoos are pH balanced hair cleaners.

Chapter 6: Solutions and Other Mixtures • Common kitchen acids: apple juice, lemon juice, orange juice, vinegar • Common kitchen bases: milk, baking soda, baking powder