Supplementary Education Service - SCIENCE 7-1-3.pptx

Supplementary Education
Service – Science
Level 7
Unit 1: The Investigatory Process and Matter
Chapter 3: Solutions, Acids, and Bases

Objectives:
At the end of the session, the students should be able
to:
1. differentiate unsaturated, saturated, and
supersaturated solutions;
2. investigate the properties of unsaturated and saturated
solutions;
3. identify and explain the factors that affect solubility;
4. express concentrations of solutions quantitatively by
preparing different concentrations of mixtures
according to use and availability;

Objectives:
5. explain the difference between percent by weight and
percent by volume of solutions;
6. state the concept of pH;
7. cite the importance of pH in daily life;
8. distinguish common acids from bases;
9. investigate the properties of acids and bases using
natural indicators;
10.investigate the action of acids and bases on metals
and other materials; and

Objectives:
11.investigate neutralization of acids and bases.

Introduction:
Solutions have properties that make them highly useful in
everyday life.
Examples:
o Stainless steel, a solid solution of iron with some
chromium dissolved in it, is used widely due to its
resistance to corrosion.
o A tincture of iodine, made up of water, alcohol, and
iodine crystals, is commonly used to prevent infection on
wounds.

Introduction:
o Sugar solutions are used in beverages and drinks, while
saline solutions extend the shelf life of fermented
vegetables and fruits.
o Tea and lemonade are examples of extracts that are
dissolved in water.
o Some minerals that plants need from the soil are
absorbed by the plants only in the form of solutions.

Introduction:
Solutions can be acidic, basic, or neutral. For example,
vinegar is acidic and tastes sour, while bases like lye or
sodium hydroxide are slippery. Automobile batteries
require sulfuric acid to function. Bases neutralize acids,
and vice versa.

Solutions
When a spoonful of salt is poured into a glass of water,
the salt (a substance) will dissolve in the water (another
substance), resulting in the formation of a salt solution.
A solution is made up of two components: the solute,
which is the substance present in a smaller amount, and
the solvent, which is the substance present in a larger
amount. The solvent dissolves another material, whereas
the solute is the substance that is dissolved.

Solutions
A solution that has water as the solvent is generally
called an aqueous solution.
Properties: Particles in solutions are too tiny to be seen by
the naked eye, making solutions appear homogeneous.
Solutions cannot be filtered because the particles can
pass through the holes of filter paper. Unlike colloids,
solutions do not scatter light.

Solutions
Classification: Solutions may be classified according to the
state of the solvent, their solubilities, and their
concentrations. Solutions can be in the form of a solid,
liquid, or gas.
States of Solute and Solvent: A solute or a solvent can be a
gas, a liquid, or a solid, but the final state of the solution
is determined by the state of the solvent.

Solubility
The maximum amount of solute that can be dissolved in a
given amount of solvent at a specific temperature is called
solubility. It is usually expressed as grams of solute per 100
g of solvent.
In the solution process, the terms soluble and miscible refer
to solids dissolved in liquids and liquids dissolved in
liquids, respectively. A solid substance that dissolves
completely in a given solvent is said to be soluble. Sodium
chloride (NaCl) or table salt is soluble in water. Two liquids
that completely mix with each other are said to be
miscible. For example, acetic acid is miscible in water.

Solubility
Solutes and solvents that differ in state and do not
dissolve appreciably are insoluble. For example,
naphthalene balls do not dissolve in water. Meanwhile,
solutes and solvents of the same state that do not mix
appreciably are immiscible. Examples of immiscible
substances are oil and water.

Saturated, Unsaturated, and Supersaturated
Solutions
A solution that has reached its maximum solubility is
referred to as a saturated solution. For example, when salt
is added to water at 25°C until no more can be dissolved,
the solution becomes saturated.
An unsaturated solution is a solution that can still dissolve
additional solute in a given amount of solvent at a given
temperature. For instance, if 15.0g of salt readily dissolves
when added to 100 g of water at 25°C, the solution is
unsaturated because it does not yet contain the
maximum amount of solute that the solvent can hold.

Saturated, Unsaturated, and Supersaturated
Solutions
Solubility of Salt at 25°C: The maximum amount of salt
that can be dissolved in 100 g of water at 25°C is 35.7 g.
This is the solubility of salt at 25°C.
A supersaturated solution is produced by preparing a
saturated solution at a higher temperature and then
cooling it. If undissolved solutes remain after cooling,
then the solution is said to be supersaturated. However,
such a solution is unstable. When a tiny “seed” of the
solute is introduced into the solution, the dissolved solute
particles will come out of the solution as pure crystals.

Factors Affecting Solubility
The solubility of one substance in another substance is
affected by the nature of the solute and the solvent,
temperature, and pressure.
🖎 Nature of Solute and Solvent: The solubility of a solute in
a solvent depends on the nature of both the solute and
the solvent. Polar solvents dissolve polar solutes, and
nonpolar solvents dissolve nonpolar solutes.

🖎 Temperature: The solubility of some solutes is affected
by temperature. Solids are generally more soluble in
liquids at higher temperatures. For gases, most become
less soluble in liquids as the temperature increases.
Solubility Curves: The solubility of potassium bromide
(KBr), potassium nitrate (KNO3), and sodium nitrate
(NaNO3) in water increases with temperature. The
solubility of cerium (III) sulfate decreases with
increasing temperature.

Solubility of Gases in Liquids: The solubility of gases in
liquids decreases as the temperature increases. This is
observed in the behavior of dissolved gases such as O2,
N2, and CO2 in water.
Effect on Aquatic Life: Variations in temperature affect
aquatic animals in bodies of water such as rivers and
lakes. An increase in the temperatures of rivers and lakes
leads to reduced concentrations of dissolved oxygen,
which can affect the survival of most living organisms.

Thermal Pollution: The reduced solubility of oxygen gas
in hot water is related to thermal pollution, which is
the sudden change in the temperature of a body of
water as a result of human activities.
🖎 Pressure: Pressure does not affect the solubility of
liquids and solids. However, it greatly affects the
solubility of gases in liquids. This is observed in
carbonated drinks such as soda, beer, and champagne,
which contain carbon dioxide dissolved in liquid.

Concentrations of Solutions
Solutions may be classified on the basis of the amounts of
solvent and solute present.
When a solution contains a relatively large amount of
solute per unit volume, the solution is said to be
concentrated. However, if the solution contains a relatively
small amount of solute per unit volume, the solution is
said to be diluted.

Concentrations of Solutions
The concentration of a solution is the amount of solute
present in a given quantity of solution.
The most common ways of expressing concentration are
by percent by mass and percent by volume.

Percent by Mass (Sample Problems)
1. What is the mass percentage of a solution that is made
by dissolving 4 g NaCl in 100 g water?
2. A medical solution used in a hospital is 0.9% NaCl by
mass. How many grams of NaCl are present in 100 g of
the solution?
3. Dimercaprol, a compound used as an antidote for
mercury or arsenic poisoning, is prepared by mixing
100 mg of dimercaprol with 700 mg of peanut oil. What
is the percent by mass of dimercaprol in this solution?

Percent by Volume (Sample Problems)
1. What is the volume of alcohol in 500 mL of wine that
contains 12% alcohol by volume? What is the wine's
proof number?
2. A bottle of lambanog is 80 proof. What is the percent by
volume of alcohol in the bottle?

Percent by Mass/Volume (Sample Problem)
1. A medical technologist needs to prepare 1 L of a 5%
(m/v) NaCl solution. How many grams of NaCl must be
weighed out?

Acids and Bases
Acids and bases are indispensable compounds due to
their vital roles in our daily lives.
Examples of Acids in Nature: When an ant bites a termite, it
sprays formic acid into the wound, causing it to sting or
hurt.
Acids in the Kitchen: Acetic acid can be used to remove
calcium carbonate deposits (“scales”) from pots and pans.

Acids and Bases
Properties of Acids and Bases:
🖎 Acids have a sour taste, are corrosive, and can cause
color changes in plant dyes. They turn blue litmus
paper red.
🖎 Bases have a bitter taste, are slippery or slimy to the
touch, are also corrosive, and change the color of red
litmus paper to blue.

Acids and Bases
Acids and Bases in the Human Body:
🖎 Acid forms in the mouth as a result of bacteria
breaking down sugars, which can cause tooth decay.
This can be prevented by limiting sugar intake and
regular brushing with toothpaste, which contains a
base that neutralizes the acid.
🖎 The human skin secretes natural acids to inhibit
bacterial growth, and the stomach secretes
hydrochloric acid to help break down food.

Common Acids and Bases
There are many different kinds of acids and bases used in
various industries and everyday life.
🖎 Sulfuric acid (H2SO4) is used in the manufacture of
plastics, paints, photographic films, rayons, and
fertilizers.
🖎 Citric acid can be found in candies and similar products
to improve their taste.
🖎 Hypochlorous acid (HClO) is used in swimming pools to
prevent the growth of bacteria.

Common Acids and Bases
🖎 Sodium Hydroxide (NaOH), also known as lye, is used in
the production of soap. A certain amount of a base is
also added to shampoos to improve their “slippery
feeling.”

Indicators of Acids and Bases
Complex organic substances called acid-base indicators
can distinguish an acid from a base and detect acids and
bases in solutions. These substances show distinct color
changes when they come in contact with an acid or a
base.
Indicators can also be prepared from certain plants. The
red, purple, and blue colors of these plants indicate the
presence of an organic substance called anthocyanin.
Extracts from these plants change their color when they
are exposed to compounds that are acidic or basic.

The pH Scale
Some liquid detergents and soaps are advertised as
having acidic or basic pH.
The pH is a measure of the acidity or basicity of a solution.
The pH scale ranges from 0 to 14. A solution with a pH less
than 7.00 is acidic; a solution with a pH above 7.00 is basic;
and a solution that has a pH equal to 7.00 is neutral.

The pH Scale
The stronger the acid, the lower the pH, and the stronger
the base, the higher the pH.
The pH of a solution can be measured using a pH paper or
a pH meter. The latter produces a more accurate and
direct measurement of pH because it can measure pH
values of up to 0.001 units.

Importance of pH
Abnormal blood pH can lead to serious illness or death.
The normal pH of human blood is between 7.35 and 7.45.
Acidosis (fall in blood pH) can be caused by heart and
kidney failure, diabetes, and persistent diarrhea. Alkalosis
(rise in blood pH) may occur due to overbreathing caused
by anxiety, hysteria, or exposure to high places.
The normal pH of saliva is 7.4, which can neutralize the
acid in the mouth. The pH of human tears ranges from 6.5
to 7.6. Shampoos for infants and children are formulated
at this pH level to prevent eye irritation.

Importance of pH
Shampoos for adults generally have a pH between 4.5 and
7. A higher pH can cause dryness and splitting of hair. Hair
remover solutions have a high pH of 12, which breaks the
bond holding together protein molecules called keratin in
hair.
Controlling the pH is important in the production of wine,
vinegar, cheese, and tomato ketchup. These products
have their distinct tastes because their pH is maintained
at a certain level.

Importance of pH
The pH plays an important role in controlling the growth
of microorganisms. Most bacteria grow in an environment
with a pH of 6.5 to 7.5. Molds prefer neutral to slightly
acidic conditions, while yeasts can grow at a pH range of 4
to 6. Lower pH levels can prevent food spoilage and
prolong the shelf life of food items.
Swimming pools are often treated with hypochlorous acid
(HClO) to prevent the growth of algae and bacteria. The
pH of pool water must be maintained between 7.2 and 7.4
to prevent eye irritation.

Neutralization of Acids and Bases
Acids and bases have the ability to neutralize each other.
This is a fundamental property of acids and bases.
Acids can react with metals and other materials. This
property makes them useful in various chemical reactions
and industrial processes.

1. Solutions can be solid, liquid, or gas. A solution consists
of a solute and a solvent. A solute can be a gas, a
liquid, or a solid, but the final state of the solution is
determined by the state of the solvent. A solution that
has reached its maximum solubility is called a
saturated solution. A solution that can still dissolve
more solute in a given amount of solvent at a given
temperature is an unsaturated solution. Setting a
saturated solution at a higher temperature produces a
supersaturated solution.

2. A solid substance that dissolves completely in a given
solvent is said to be soluble. Two liquids that
completely mix with each other are said to be miscible.
Solutes and solvents that differ in state and do not
dissolve appreciably are insoluble. Solutes and solvents
of the same state that do not mix appreciably are-
immiscible.
3. The solubility of one substance in another substance is
affected by the following factors: the nature of the
solute and the solvent, temperature, and pressure.
Solids are generally soluble in liquids at higher
temperatures. Unlike solids or liquids, most gases

4. When a solution contains a relatively large amount of
solute per unit volume, the solution is concentrated.
Meanwhile, a solution is diluted when it contains a
relatively small amount of solute per unit volume. The
concentration of a solution is the amount of solute
present in a given quantity of solution. It can be
quantitatively expressed as percent by mass or %
(m/m), percent by volume or % (v/v), and percent by
mass/volume or % (m/v).

5. Percent by mass, or % (m/m), of a solution refers to the
mass of the solute dissolved in 100 g of the solution.
Percent by volume, or % v/v, refers to the volume of
the solute (in milliliters) dissolved in 100 mL of the
solution. Percent by mass/volume, or % (m/v), refers to
the mass of the solute (in grams) dissolved in a volume
(in milliliters) of the solution.
6. The pH is a measure of the acidity or basicity of a
solution. The stronger the acid, the lower the pH, and
the stronger the base, the higher the pH.
Neutralization occurs when an acid reacts with a base.
Salt and water are formed in the reaction, and the pH

7. Many serious diseases thrive in over acidic
environment; thus, maintaining the body's pH balance
is important. Controlling the pH is also important in
the production of many food products. The pH also
plays an important role in controlling the growth of
microorganisms.
8. An acid is a substance that has a sour taste, is
corrosive, and can cause color changes in plant dyes. A
base, on the other hand, has a bitter taste, is slippery
or slimy to the touch and is also corrosive.

Supplementary Education Service - SCIENCE 7-1-3.pptx

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Supplementary Education Service - SCIENCE 7-1-3.pptx