Solutions, Acids and Bases. Chapter 8. Formation of Solutions. For a solution to form, one substance must dissolve in another . Even though we usually think of a solid dissolving in a liquid, any state of matter can become part of a solution.
For a solution to form, one substance must dissolve in another.
Even though we usually think of a solid dissolving in a liquid, any state of matter can become part of a solution.
Scuba divers breathe with the aide of compressed air(78% nitrogen). As a diver descends (the deeper the diver goes), the greater is the pressure of the air in the diver’s lungs and the more nitrogen dissolves in the blood and tissues of the body. If divers surface too quickly, the nitrogen that has dissolved in the blood and tissues can bubble out of the solution and become trapped in joints causing great pain (“the bends”).
Substances can dissolve in water three ways:
Dissociation of Ionic Compounds: sodium chloride crystal and water
Dispersion of Molecular Compounds: hard candy and saliva
Ionization of Molecular Compounds: HCl and water
The process in which neutral molecules
gain or lose electrons is known as ionization.
heat of solution
Lemonade, Iced tea, and hot tea can all “hold” different concentrations of sugar.
They each have different factors for solubility of sugar.
Three factors affect the solubility of a solute.
-“like dissolves like”
Concentration can be expressed as percent in three ways.
Sodium hydroxide (a base) is added to a mixture of animal/vegetable fats and boiled until the sodium hydroxide reacts with the fats producing glycerol and soap. After glycerol is separated from the soap, the soap is purified and other chemicals are mixed in for color and scent.
An acid is a compound that produces hydronium ions when dissolved in water.
Some general properties of acids include sour taste, reactivity with metals, and ability to produce color changes in indicators.
Sour Taste: lemons, grapefruits, limes, and oranges (citric acid)
vinegar (acetic acid)
Reactivity With Metals: aluminum foil over spaghetti sauce (citric acid) – a single replacement reaction
Color Changes in Indicators: litmus paper (a common indicator) turns red in the presence of an acid
A base is a compound that produces hydroxide ions when dissolved in water.
Some general properties of bases include bitter taste, slippery feel, and ability to produce color changes in indicators.
Bitter Taste: unsweetened chocolate, many cough syrups
Slippery Feel: wet soap, some wet rocks
Color Changes in Indicators: bases turn litmus paper blue
In a basic solution, is red
In an acidic solution, is colorless
Natural indicators: flowers, like hydrangeas
In basic soil, flowers are pink
In acidic soil, flowers are blue
The reaction between an acid and a base is called neutralization.
FISH – BASE LEMON – ACID
REACTION MAKES FISH TASTE LESS BITTER
This reaction is called neutralization.
The neutralization reaction between an acid and a base produces a salt and water.
Certain compounds of chlorine are dissolved in swimming pool water to prevent the growth of bacteria.
The concentration of hydronium ions in solutions must be carefully controlled.
Determining the concentration of hydronium or hydroxide ions is one way to determine the acidity or basicity of a solution.
Weak acids and bases ionize or dissociate only slightly in water.
Class Participation Opportunity:
Write a research paper that includes the following concepts:
1. compounds in blood
2. blood flow through the body
3. maintaining blood’s pH
4. scientists who have contributed to our understanding of blood
Your paper should include information found on pages 250-253. It should also contain information from two other sources.
Possible investigative questions:
1. How can you determine the solubility of a substance in water?
Comparing Solubilities and Rates of Dissolving
2. How does surface area affect the rate of dissolving and solubility?
3. How does temperature affect the rate of dissolving and solubility?
4. Which antacid neutralizes stomach acid with the smallest number of drops?
5. Which brand of antacid neutralizes the most acid per dose?