solutions of acids & bases prepared by the teacher: ronak ahmed duhok international school...
TRANSCRIPT
Solutions of acids & bases
Prepared by the teacher: Ronak AhmedDuhok International School
2012-2013
Chemistry – Grade 9
If you eat large amounts of foods….!!
You’ll have a terrible case of indigestion
If you had an upset stomach, you’ll fell
a stomach ache. Antacids may help
you
How antacid is working?
• Antacid: is a weak base that neutralizes a strong acid in your stomach.
Strengths of Acids & Bases
• Acids & bases can be strong or weak.
The strength of an acid or a base is not the same as the concentration of an acid or base.
The concentration of an acid or a base
is the amount of acid or base dissolved in water.
The strength of an acid or base
Depends on the number of molecules that break apart when the acid or base is dissolved in water.
Strong acids & Weak AcidsAs an acid dissolves in water, the acid’s molecules break apart and produce hydrogen ions, (H+).
When an Acid is strong or weak?
If all of the molecules of an acid break apart
Strong acid Weak acid
If only a few molecules of an acid break apart
Sulfuric acidH2SO4
Car battery
Nitric acidHNO3
fertilizers
Hydrochloric acid HCl
stomach
Acetic acid(HC2H3O2)
vinegar
Citric acid (lemons)C6H8O7
Carbonic acid (soft drink)
H2CO3
Strong Bases & Weak Bases
When all molecules of a base break apart in
water to produce hydroxide ions (OH-)
Strong base Weak base
If only a few molecules of a
base break apart
Sodium hydroxide
NaOHSoap
Calcium hydroxideCa(OH)2
Cement
Ammonium hydroxide
NH4OHCleaners
Aluminum hydroxide
Al(OH)3
Antacid
Potassium hydroxideKOH
Battery electrolyte
Neutralization
When the base in an antacid meets stomach acid, a reaction occurs.
Neutralization: is the reaction between acids and base.
Why Acids & Bases neutralizing one another?
Hydrogen ions (H+)In acid
Hydroxide ions (OH-)In base
react
H2O
Neutral
Other ions from the acid and base dissolved in the water. when the water evaporates, these ions join to form a compound called a salt.
The pH Scale
An indicator such as litmus, can identify whether a solution contains an acid or base.
Acid base
The pH of a solution is a measure of the hydronium ion concentration in the solution.
• Solution PH =7 neutral
• Distilled water has a pH of 7.• Basic solutions pH = > 7.• Acidic solutions pH= < 7.
The solution is neither acidic nor basic
Use of indicators to determine pH
what is the role of combination of indicators?
It can be used to find out how basic or how acidic a solution is.
This can be done if the colors of the
indicators are known at different
pH value.
How the pH Indicator is working?
1. The strips of pH paper contain several different indicators.
2. These strips were dipped into two different solutions.
3. The pH of each solution is found by comparing the colors on each strip with the color of indicator scale provided.
Video
It is often used to test the pH of water in pools and aquariums.
Where this kind of indicator is used?
pH meter• Is another way to find the pH of a solution.• These pH meters can detect and measure hydronium
ion concentration electronically.
video
pH and the Environment • Living things depend on having a steady pH in their
environment. Prefer acidic soil, pH (4-6)
Need basic soil, pH (8-9)
Plants may also have different traits under different growing condition!
• Ex:
The color of hydrangea flowers
varies when the flowers are grown in
soils that have different pH values.
• Many organisms living in lakes and streams need a neutral pH to survive.
• Most rain has a pH between (5.5 and 6).When the rain is acidic and how?
When rainwater reacts with compounds found in air pollution, acids are formed and the rain water’s pH decrease.Most acid rain has a pH between (4 and 4.5).
Salts
• An ionic compound that forms when a metal atom replaces the hydrogen of an acid.
What will be produced if an acid neutralize a base?
A salt and water will be produced
Salts
Table salt is only one example of a large group of compounds that called salt
Uses of SaltsSalts have many uses in industry and in homes.
1. Sodium chloride used in foods
its also used to make other compounds,
including sodium hydroxide, soap &
sodium hydrogen carbonate.
2. Ammonium nitrate is a salt used to
make fertilizers.
3. Calcium sulfate is used to make wallboard (used
in construction).