Chapter 25Chapter 25

Acids & BasesAcids & Bases

25.1- Acids, Bases, & pH

25.1- Acids, Bases, & pH

Why is pH important?The water we drink has to be tested so it is safe.

Water with a pH that is too high may clog water pipes.

Water with a pH that is too low may corrode the pipes.

Why is pH important?The water we drink has to be tested so it is safe.

Water with a pH that is too high may clog water pipes.

Water with a pH that is too low may corrode the pipes.

Acids, Bases, & pHAcids, Bases, & pH

A solution with a pH value that is less than 7 contains an acid.

A solution with pH values greater than 7 contains a base.

An acid is a chemical that contributes hydrogen ions, H+, to a solution.

A base is a chemical that contributes hydroxyl ions, OH-, to a solution.

A solution with a pH value that is less than 7 contains an acid.

A solution with pH values greater than 7 contains a base.

An acid is a chemical that contributes hydrogen ions, H+, to a solution.

A base is a chemical that contributes hydroxyl ions, OH-, to a solution.

pH and the pH scalepH and the pH scale

pH describes the exact concentrations of H+ ions in a solution.

Most instruments that measure pH use a pH scale that runs from 0 to 14.

pH 1 is strongly acidic.pH 14 is strongly basic.A solution that has a pH of 7 has equal numbers of H+ and OH- ions & is called a neutral solution.

pH describes the exact concentrations of H+ ions in a solution.

Most instruments that measure pH use a pH scale that runs from 0 to 14.

pH 1 is strongly acidic.pH 14 is strongly basic.A solution that has a pH of 7 has equal numbers of H+ and OH- ions & is called a neutral solution.

pH and the pH scale pH and the pH scale

The more H+ ions there are in a solution, the lower the pH value.

So… fewer H+ ions in a solution means higher pH value.

Another way of looking at the scale is to see that as the pH numbers increase, the amount of H+ ions decrease by powers of 10.

The more H+ ions there are in a solution, the lower the pH value.

So… fewer H+ ions in a solution means higher pH value.

Another way of looking at the scale is to see that as the pH numbers increase, the amount of H+ ions decrease by powers of 10.

Acid-Base ChemistryAcid-Base Chemistry

Water plays an important role in acid and base chemistry.

Water is both a weak acid and a weak base.

The water molecule can split or ionize into H+ and OH- ions.

2H2O H3O+ + OH-

Water plays an important role in acid and base chemistry.

Water is both a weak acid and a weak base.

The water molecule can split or ionize into H+ and OH- ions.

2H2O H3O+ + OH-

Acid-Base Chemistry cont…

Acid-Base Chemistry cont…

The double-headed arrow in the equation means that water, if left alone, is always in equilibrium with its ions.

What does this mean… The rate at which water breaks down into ions is the same as the rate at which the ions re-form into water.

The double-headed arrow in the equation means that water, if left alone, is always in equilibrium with its ions.

What does this mean… The rate at which water breaks down into ions is the same as the rate at which the ions re-form into water.

Acid-Base Chemistry cont…

Acid-Base Chemistry cont…

Specific pH values are needed within your body.

For your stomach to digest food, Hydrochloric acid (pH of 1.4) is needed to break down the protein molecules in the food.

These molecules need to be absorbed within your body.

Specific pH values are needed within your body.

For your stomach to digest food, Hydrochloric acid (pH of 1.4) is needed to break down the protein molecules in the food.

These molecules need to be absorbed within your body.

Acid-Base Chemistry cont…

Acid-Base Chemistry cont…

Reactivity of acids & bases means that these chemicals have many uses.

Lye (pH 13) is used to unclog drains.

Sulfuric acid (pH 1) is an industrial product, such as cleaning impurities form gasoline.

Reactivity of acids & bases means that these chemicals have many uses.

Lye (pH 13) is used to unclog drains.

Sulfuric acid (pH 1) is an industrial product, such as cleaning impurities form gasoline.

Electrolytes & NonelectrolytesElectrolytes & Nonelectrolytes

Current is a flow of charge.When a solution contains dissolved ions (charged particles), it can conduct current.

Chemicals that conduct current when dissolved in water are called electrolytes.

Current is a flow of charge.When a solution contains dissolved ions (charged particles), it can conduct current.

Chemicals that conduct current when dissolved in water are called electrolytes.

Electrolytes & Nonelectrolytes cont…

Electrolytes & Nonelectrolytes cont…

All acids and bases are electrolytes because they contribute ions to a solution.

Other chemicals do not form ions when they are dissolved in solution. Sugar dissolved in water is an example of a non-electrolyte.

All acids and bases are electrolytes because they contribute ions to a solution.

Other chemicals do not form ions when they are dissolved in solution. Sugar dissolved in water is an example of a non-electrolyte.

Common ChemicalsCommon Chemicals

Household chemical

Acid or Base

pH

Lemon juice Acid 2

Vinegar Acid 3

Soda Water Acid 4

Baking soda Base 8.5

Bar soap Base 10

Ammonia Base 11

pH of Common Substances

pH of Common Substances

To measure pH, you will use a pH indicator- a chemical that changes color at different pH values.

To measure pH, you will use a pH indicator- a chemical that changes color at different pH values.

pH and Your BloodpH and Your Blood

It is very important that your blood pH stay within the normal range.

You can regulate the pH of your blood simply by breathing!

If you hold your breath, more carbon dioxide enters your blood. If you hyperventilate, you blow off carbon dioxide.

It is very important that your blood pH stay within the normal range.

You can regulate the pH of your blood simply by breathing!

If you hold your breath, more carbon dioxide enters your blood. If you hyperventilate, you blow off carbon dioxide.

pH and Your Blood cont…

pH and Your Blood cont…

When CO2 dissolves, H+ ions are produced in solution.

Therefore, the more CO2 in your blood, the more acidic your blood will become.

So… If you breath slowly, the added CO2 makes your blood more acidic.

When you breathe normally, your blood pH ranges between 7.35 and 7.45.

When CO2 dissolves, H+ ions are produced in solution.

Therefore, the more CO2 in your blood, the more acidic your blood will become.

So… If you breath slowly, the added CO2 makes your blood more acidic.

When you breathe normally, your blood pH ranges between 7.35 and 7.45.

25.2-Acid Rain25.2-Acid Rain

Rain, snowfall, or any precipitation happens to be naturally acidic.

Why…this mixes with carbon dioxide and forms small amounts of carbonic acid.

Normal pH of rain is around 5.6Any rain, snow, or fog that has a pH lower than 5.6 is called acid rain or acid precipitation.

Rain, snowfall, or any precipitation happens to be naturally acidic.

Why…this mixes with carbon dioxide and forms small amounts of carbonic acid.

Normal pH of rain is around 5.6Any rain, snow, or fog that has a pH lower than 5.6 is called acid rain or acid precipitation.

Acid Rain cont…Acid Rain cont…

The chief indicators of acid rain in the atmosphere are the gases sulfur dioxide, sulfur trioxide, nitrogen oxide, and nitrogen dioxide.

Many of these gases are created by industrial processes, traffic, and power plants!

The chief indicators of acid rain in the atmosphere are the gases sulfur dioxide, sulfur trioxide, nitrogen oxide, and nitrogen dioxide.

Many of these gases are created by industrial processes, traffic, and power plants!

THE END!!THE END!!