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Solutions of acids & bases Prepared by the teacher: Ronak Ahmed Duhok International School 2012-2013 Chemistry – Grade 9.

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Presentation on theme: "Solutions of acids & bases Prepared by the teacher: Ronak Ahmed Duhok International School 2012-2013 Chemistry – Grade 9."— Presentation transcript:

1 Solutions of acids & bases Prepared by the teacher: Ronak Ahmed Duhok International School Chemistry – Grade 9

2 If you eat large amounts of foods….!!

3 You’ll have a terrible case of indigestion If you had an upset stomach, you’ll fell a stomach ache. Antacids may help you

4 How antacid is working? Antacid: is a weak base that neutralizes a strong acid in your stomach.

5 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.

6 Strong acids & Weak Acids As an acid dissolves in water, the acid’s molecules break apart and produce hydrogen ions, (H + ). If all of the molecules of an acid break apart Strong acidWeak acid If only a few molecules of an acid break apart Sulfuric acid H 2 SO 4 Car battery Nitric acid HNO 3 fertilizers Hydrochloric acid HCl stomach Acetic acid (HC2H3O2) vinegar Citric acid (lemons) C 6 H 8 O 7 Carbonic acid (soft drink) H 2 CO 3

7 Strong Bases & Weak Bases When all molecules of a base break apart in water to produce hydroxide ions (OH - ) Strong baseWeak base If only a few molecules of a base break apart Sodium hydroxide NaOH Soap Calcium hydroxide Ca(OH) 2 Cement Ammonium hydroxide NH 4 OH Cleaners Aluminum hydroxide Al(OH) 3 Antacid Potassium hydroxide KOH Battery electrolyte

8 Neutralization When the base in an antacid meets stomach acid, a reaction occurs. Neutralization: is the reaction between acids and base. Hydrogen ions (H + ) In acid Hydroxide ions (OH - ) In base react H2OH2O 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.

9 The pH Scale An indicator such as litmus, can identify whether a solution contains an acid or base. Acidbase The pH of a solution is a measure of the hydronium ion concentration in the solution.

10 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

11 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.

12 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. It is often used to test the pH of water in pools and aquariums. Where this kind of indicator is used?

13 pH meter Is another way to find the pH of a solution. These pH meters can detect and measure hydronium ion concentration electronically.

14 pH and the Environment Living things depend on having a steady pH in their environment. Prefer acidic soil, pH (4-6)

15 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.

16 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).

17 Salts A salt and water will be produced Table salt is only one example of a large group of compounds that called salt

18 Uses of Salts Salts 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).


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