Solutions
Textbook Chapter 8 p. 259-281
Read p 259-266 Solutions and other Mixtures
Go to Chem4Kids and see what is different between solutions, suspensions, and colloids.
As discussed briefly in chapter 2, heterogeneous mixtures are a mixture of different amounts of substances that are not chemically changed. For example, a fruit salad is a heterogeneous mixture. A suspension is a heterogeneous mixture with large more or less evenly distributed particles that eventually settle out, like orange juice. A colloid is a heterogeneous mixture with particle to small to settle out.
Homogeneous mixtures are solutions that becomes a uniform substance, like salt water. The salt is the solute and the water is the solvent of the solution.
The coffee is the solvent, the sugar is the solute, and the sweeten coffee would be the solution.
Read p 267-273 How Substances Dissolve
What affects solubility?
Water: common solvent or universal solvent
Water can dissolve ionic compounds because of its structure. The hydrogen and oxygen atoms of the water are held together by covalent bonds, but the attract of the electrons is stronger in the oxygen atoms therefore the shared electrons spend more time around the oxygen atom. This gives the molecule a partial negative charge. This uneven distribution of elections combined with its bent shape cause it to be a polar compound.
Hydrogen bonding pulls oxygen from other water molecules closed together to form a partial covalent bond. This makes water molecules close together making it dense with a high boiling point.
Nonpolar compounds have electrons equally distributed among its atoms. They usually will not dissolve in water. Examples of nonpolar compounds are olive oil, oil-based paint, and iodine.
A rule of thumb in chemistry is that "like dissolve like." There for water, polar, will not dissolve oil, nonpolar.
Read p 276-280
Solubility and Concentration
Solubility is the maximum amount of a solute that will dissolve into a given solvent at a given temperature. Different substances have different solubility. The concentration is the amount of a substance in a given quantity of a mixture.
What is the difference between unsaturated, saturated and supersaturated solutions?-- make these links.
The rock candy suckers you have been eating is a result of a supersaturated solution. A supersaturated solution is a solution that contains more solute than required to reach equilibrium at a given temperature. A supersaturated solution is made by taking a saturated solution and heating it to allow more of the solute to be dissolved. In the case of rock candy sugar is dissolved in water to make a saturated solution and then it is boiled to add more sugar. As the supersaturated sugar water cools it turns to crystals
When the sugar has completely crystallized you have a sucker.
Complete the first three assignments below.
Chapter 9 p. 293-313
Acids, Bases and pH
Acids are compounds that increase the number of hydronium ions when dissolved in water. Indicators help identify acids by responding to the concentration of hydronium ions in water by changing color. Litmus paper is an indicator.
4 Properties of Acids
- 1. Taste sour.
- 2. Turn blue litmus paper red.
- 3. Contain combined hydrogen.
- 4. Release hydrogen in water solutions or ionize in water.
Neutral Solution
Acid
A substance that dissolves in water to give a solution that conducts electricity is called an electrolyte.
Bases are any compound that increases the number of hydroxide ions when dissolved in water.
4 Properties of Bases
- 1. Tastes bitter.
- 2. Feels slippery.
- 3. Turns red litmus blue.
- 4. Releases hydroxide ions in water solutions.
pH is a value used to express the acidity or alkalinity of a solution. It indicates the concentration of hydronium ions.
Reactions of Acids and Bases
A reaction between acids and bases is called a neutralization reaction. Strong acids and bases react to form water and salt. Salt is an ionic compound that forms when a metal atom replaces the hydrogen of an acid. Salts are all around us. Some common examples include: baking soda, sodium stearate in soap, sodium lauryl sulfonate in detergent, and calcium chloride in de-icers.
Acids, bases and salts are very useful in the home. They are used to make soaps, detergents, disinfectants, bleach, shampoos, and products to keep fruit and vegetables fresh.
Other Helpful Sources:
Acids, Bases, Salts and pH Review
Physical Science Linkpage
Assignments
On paint make a picture of three glass labeled solution, suspension and colloid illustrating the difference between them. Print off your drawing do not save.
Describe the factors that affect solubility.
Describe how to make a saturated solution into a supersaturated solution.
Create a chart of solutions indicate the solute, solvent and whether it is unsaturated, saturated, or supersaturated. Include at least 15 solutions.
Blood Substitutes p. 274-275
You need to clean up a spill of oil-based liquid furniture polish and another spot where some lemon-lime soda has spilled and dried. Explain how you would apply the "like dissolve like" rule to clean up these two spills. Use the words polar and nonpolar in you explanations.
Compare and contrast the properties of acidic, basic and neutral solutions in a three circle Venn diagram.
Draw an illustration of an acid, base and neutral solution showing the molecules in each container. Label each container and label the different molecules in each.
How do soaps work? Type in this question to WikiAnswers, Google, Ask etc. and find the answer. Remember the "like dissolve like" rule and think about how oils can be removed from material or hands when washing with water, but they are not "likes." Also read p. 308 in your text book.
Take the Solubility Quiz and print the results.
Acid and Base Lab -Identify 15 common acids and bases found in your school and classify each as an acid or a base.
Saturation Class Lab
Chapter 7-8 Review
Chapter 7-8 Test
