Acids, Bases and Salts. 2. CHAPTER. You have learnt in your previous classes that the sour and bitter tastes of food are due to acids and bases, respectively. Acids, Bases and Salts. 5. We use in our daily life a large number of substances such as lemon, tamarind, common salt, sugar and vinegar. Do they have. Chapter Acids, Bases, and Salts. Key topics: pH scale; acid-base properties of water. Ka = acid ionization constant; Kb = base ionization constant. Polyprotic.
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1 Acids and Bases. 2 Strength of Acids and Bases. Lab Acid Concentrations. 3 Salts. Lab Be a Soda Scientist. Virtual Lab How is the acidic concentration of a. X – Science. AK. Class CHAPTER – 2. ACIDS, BASES AND SALTS (Notes). ❑. Acids. Bases. – Sour in taste. – Bitter in taste. – Change the blue litmus to red. ACIDS, BASES AND SALTS. Before we discuss the ways in which chemists manage to classify all of the various substances in the universe, we should spend .
When sodium metal is placed in water. When dissolved in water. It is the presence of a base that give unflavored milk of magnesia its bitter taste. Bases release hydroxide ions in water solutions.
A bitter taste is characteristic of all bases. Hydrochloric acid is also used to clean brick and tile. A common indicator. Water solutions of calcium hydroxide. It is these OH1. Calcium hydroxide. How Bases are Prepared: Bases may be prepared by the reaction of water and very reactive metals. Ammonia is also used as a cleaning agent. Strong solutions of this base are very caustic. Sodium hydroxide is used in the manufacture of soap.
Properties of Salts: The salty taste of ocean water is due to the presence of salts such as sodium chloride and magnesium bromide. Some salts are composed of metallic polyatomic ions and nonmetallic polyatomic ions ammonium nitrate is composed of ammonium ions and nitrate ions. The salt most familiar to all of us is table salt -. There are many different salts present in salt water: Baking soda is the salt sodium bicarbonate.
In general. Many chemical compounds may be classified as salts. Magnesium sulfate. Since acids and bases react to form water and salt neutralization reactions hydrolysis reactions are the reverse of neutralization reactions. Salts consist of tightly bonded ions. How does this happen? The ions of opposite charge attract one another and combine to form sodium hydroxide and carbonic acid: Some salt solutions. In water. This accounts for the fact that salt solutions are generally electrolytes.
At the same time. From conductivity experiments we know that sodium hydroxide. H2CO3 is the acid present in soda water. Carbonic acid. Since carbonic acid decomposes on standing to form CO2 gas and H2O. Uses of Salts: Name of Formula Uses salt ammonium in soldering. When the acid formed in a hydrolysis reaction is stronger that the base.
When an acid and base react. The compounds ionize releasing hydrogen. Such a solution is said to be neutral and the sodium chloride has not undergone hydrolysis. When both the acid and the base in a hydrolysis reaction are equally strong or equally weak. This occurs because the hydrochloric acid and the sodium hydroxide first ionize. Salts may be prepared by three methods: Such a reaction.
Ionization Ionization is the formation of ions in solution. Bases Bases are substances which ionize to produce hydroxide ions in water solutions.
Hydrolysis Hydrolysis is a reaction of a salt with water to form a weak acid or base. Since these are mobile in solution. Endpoint Endpoint is the point in a titration where equal amounts of reactants are present. Acids taste sour and turn litmus red. Some ionize more than others. When a metal reacts with a nonmetal.
Salts Salts are crystalline compounds composed of the negative ions of an acid and the positive ions of a base.
How to teach acids, bases and salts
Dissociation Dissociation is the separation of ions in solution. Titration Titration is a technique for measuring the relative strength of a solution.
They taste bitter. Neutralization Neutralization is the reaction of an acid and a base to form a salt plus water. At the same time sodium ions and chloride ions remain as aqueous salt. If not, what is its taste? Since, it does not taste sour it means, that it Table 5. It is bitter in taste. Substances like these which any other are bitter in taste and feel soapy on Lemon juice touching are known as bases bases. The nature Orange juice of such substances is said to be basic basic.
Vinegar If we cannot taste every substance, Curd how do we find its nature? Special type of substances are used Tamarind imli to test whether a substance is acidic or Sugar basic. These substances are known as Common salt indicators indicators. The indicators change their Amla colour when added to a solution Baking soda containing an acidic or a basic substance. Turmeric, litmus, china rose Grapes petals Gudhal , etc.
Do you know? It is extracted as oranges, from lichens Fig. It has a lemons, etc. When added to an acidic solution, it turns red and when Oxalic acid Spinach added to a basic solution, it turns Ascorbic acid Amla, Citrus fruits blue.
It is available in the form of a Vitamin C solution, or in the form of strips of Tartaric acid Tamarind, grapes, paper, known as litmus paper. Generally, it is available as red and blue litmus paper Fig.
Have you not read the caution? We should not taste unknown substances. They could harm us. Is there any change in colour? Note down if there is any change in colour. Perform the same activity with the following substances: Tap water, detergent solution, aerated Fig.
If possible make solutions in distilled water. Add a little water and make Table. Name those substances. Cut thin strips The solutions which do not change of the yellow paper obtained.
CBSE Guide Acids Bases and Salts class 10 Notes
These strip of turmeric paper. What do you observe? To prepare limewater, dissolve some lime chuna in water in a bottle. Stir the solution and keep it for some time. Pour a little from the top. This is lime water.
Table 5. Apply turmeric paste on a sheet of plane Now I understand why a white paper and dry it. Draw a turmeric stain on my white shirt beautiful flower with soap solution is turned to red when it is with the help of a cotton bud. You will washed with soap. It is because get a beautiful greeting card.
You may try solutions of other substances also. China Rose as Indicator China Activity 5.
Add some prepared from it Table 5. Test solution Effect on turmeric solution Remarks 1.
Lemon juice 2. Orange juice 3. Vinegar 4. Milk of magnesia 5. Baking soda 6. Lime water 7. Sugar 8. Test solution Initial colour Final colour 1.
Shampoo dilute solution 2. Lemon juice 3. Soda water 4. Sodium hydrogencarbonate solution 5.
Acids Bases Salts 1 PDF
An equilibrium expression can be written for any weak acid, and one can be written for any weak base. These expressions are useful for obtaining information about a system involving the weak acid or weak base in aqueous solutions. These expressions are derived. Acids when dissolved in water produce hydronium ions. Let HA represent any weak acid.
Ka is considered as an equilibrium constant. Bases produce hydroxyl ions when dissolved in water. In water, some bases release OH- without reaction with water while others react with water to form OH-. Combining Ki and [H2O] for the same reason given above under weak acids gives a new constant, Kb, called the dissociation constant of the base, where "b" refers to base. Although this is the expression for a base containing an amino group, the analogous expression for any base producing an OH- is the same.
Let HA represent any acid. In water it ionizes as follows and a Ka can be determined. Ka, Kb, pKa, and pKb are all constants and lists of these constants can be found in reference books. Degree of Ionization of Weak Acids and Bases. Ka and Kb can be determined experimentally by several methods. A common method is to determine the pH of a solution of the weak acid or base and calculate the Ka or Kb. Other methods use electrical conductivity or spectroscopic measurements or the measurement of a colligative property of the weak acid or base.
Only the first method will be discussed. From this information, the K'a or K'b can be calculated. When pH measurements are made with a sufficient number of solutions of different concentration of the weak acid or base, the equilibrium constant at infinite dilution Ka or Kb, no prime is obtained through extrapolation. For precise determinations of Ka, activities must be used or experimental values of K'a must be extrapolated to infinite dilution.
Ka and Kb values are used to calculate the degree of ionization percent ionization of a weak acid or base. The degree of ionization of a weak acid or base is the fraction of the total molecules of the acid or base that react with water to form hydronium or hydroxyl ions. Percent ionization is the degree of ionization expressed as a percent.
Problems involving weak acids and bases follow. Problem 9: A weak acid has a Ka of 6. When simplification is not justified, the quadratic equation must be used. With simplification: Substituting yields: 6. The answers clearly show that simplification is not justified and the quadratic formula must be used. Problem 10 : A 0. Problem 11 : A 0.
Problem 12 : What is the pH of a 2. Problem What is the ionic strength of a 0. Almost all salts dissolve completely in water at concentrations commonly used in biological research. A salt consists of ions both when in the solid form and when dissolved in water. The reaction is termed a hydrolysis. Cl- does not react to any significant extent. Some salts contain more than one ion that acts as a weak acid or base in water, for example, NH4 2CO3.
HPO acts as both a weak acid and a weak base. Whether the solution is acidic, basic, or neutral depends on the relative strength of the ions that act as acids or bases.
This can be determined from the Ka and Kb values of the acids and bases. Problem 14 : a. State whether a 0. Calculate the pH of each solution. Problem 15 : What are the final hydrogen ion concentration and pH of a solution obtained by mixing mL of 0.
One way the equilibrium is affected is through the common-ion effect. The common-ion effect is the shift in equilibrium of an ionic reaction caused by the addition of an ion that participates in the reaction. Consider the ionization of formic acid. This reaction will proceed until equilibrium is again established. When the salt, sodium formate, is added to a solution of formic acid the equilibria are also disturbed.
In this case, the pH of the solution increases, that is, becomes more basic. A second way equilibrium concentrations will be changed is by removing a product. In addition, the concentration of formate ion has increased while that of formic acid has decreased. A third way equilibrium concentrations will change is by dilution, that is, by adding water.
One reason is because the concentration of water has increased. This is analogous to the common-ion effect, although water is not an ion.Vinegar 6. See following reactions: Milk of magnesia magnesium hydroxide , which is used as an antacid, is a base; lye sodium hydroxide , which is used in the manufacture of soap, is another familiar example of base. Note that initally, the rate of increase in pH per constant amount of NaOH added continually decreases.
At this point, the rate of increase in pH per constant amount of NaOH added begins to increase until the rate of increase is maximal at 1 milliequivalent of strong base added. No comments. Ka is considered as an equilibrium constant.