Acids, Bases and Salts Science - Acids, Bases and Salts

Mild non-corrosive basic salt is

A student requires hard water for an experiment in his laboratory which is not available in the neighbouring area. In the laboratory, there are some salts, which when dissolved in distilled water can convert it into hard water. Select from the following groups of salts, a group, each salt of which when dissolved in distilled water will make it hard.

The colour of copper oxide is ____________.

The acids present in plant and animals are called ___________.

Sodium hydrogen carbonate is ___________ soda whereas sodium carbonate is __________.

Acids produce _________ ions on dissolving in water.

Common salt is obtained from sea-water by the process of _________.

State whether the following statement is true or false:
Copper sulphate crystals are always wet due to the presence of water of crystallisation in them.

All non-metallic oxides dissolve in water to form acids. [True/ False]

Which bases are called alkalis? Give an example of alkalis.

How does the flow of acid rain water into a river make the survival of aquatic life in the river difficult?

Fresh milk has a pH of 6. When it changes into curd (yoghurt) will its pH value increase or decrease? Why?

How will you test for the gas which is liberated when hydrochloric acid reacts with an active metal?

1. Name the products formed when sodium hydrogen carbonate is heated.
2. Write the chemical equation for the reaction involved in the above.

Write the chemical formula for washing soda. How may it be obtained from baking soda? Name an industrial use of washing soda other than washing clothes.

1. If you are asked to report your observations about the following two properties of acetic acid, what would you report?

1. Odour.
2. Effect on litmus.

2. If you take a pinch of sodium hydrogen carbonate powder in a test-tube and add drop-by-drop acetic acid to it, what would you observe immediately? List any two main observations.

A student is studying the properties of acetic acid in his school laboratory. List two physical and two chemical properties which he must observe and note in his record book.

In which asexual reproduction two individuals are formed from a single parent and the parental identity is lost? Draw the initial and the final stages of this type of reproduction to justify your answer. Write the event with which this process starts.

Write chemical equations for what happens when:

1. Sodium metal is added to ethanol acid.
2. Solid sodium carbonate is added to ethanol acid.
3. Ethanol acid reacts with a dilute solution of sodium hydroxide.

The pH of a salt used to make tasty and crispy pakoras is 14. Identify the salt and write a chemical equation for its formation. List its two uses.

1. Name the following:

1. Metal that can be cut by knife.
2. Lustrous non-metal.
3. Metal that exists in liquid state at room temperature.
4. Most malleable and ductile metal.
5. Metal that is best conductor of electricity.
6. Non-metal that can exist in different forms.

2. How are alloys better than metals? Give composition of solder and amalgam.

Solution A turns universal indicator blue to purple whereas solution B turns universal indicator orange to red.

1. What will be the action of solution A on litmus?
2. What will be action of solution B on litmus?
3. Name any two substances which can give solutions like A.
4. Name any two substances which can give solutions like B.
5. What sort of reaction takes place when solution A reacts with solution B?

Write the chemical formula of ammonium chloride. Explain why an aqueous solution of ammonium chloride is acidic in nature? Illustrate your answer with the help of a chemical equation.

Read the following and answer any three questions from (i) to (iv).Bleaching powder is also known as chloride of lime. It is a solid and yellowish white in colour. Bleaching powder can be easily identified by the strong smell of chlorine. When calcium hydroxide (slaked lime) reacts with chlorine, it gives calcium oxychloride (bleaching powder) and water is formed. Aqueous solution of bleaching powder is basic in nature. The material to be bleached is first passed through solution of Na OH to remove greasy matter. Then it is passed through aqueous solution of bleaching powder and very dil. HCl solution. HCl reacts with bleaching powder to liberate nascent oxygen which bleaches material.

1. Write two uses of Bleaching powder?
    
2. Bleaching powder is also known as?
    
3. A) Why does Bleaching powder gives smell of chlorine?
   B) What happens when calcium hydroxide reacts with chlorine?
   
   OR
   What happens when HCl reacts with bleaching powder?

Read the following and answer any three questions from (i) to (iv).Sodium chloride obtained from sea water or from lakes contains many impurities such as sulphates of sodium and magnesium, along with chlorides of calcium and magnesium. The chlorides of calcium and magnesium are particularly undesirable on account of their deliquescent nature.
For its purification, common salt is dissolved in minimum quantity of water to get a saturated solution from which insoluble impurities are filtered off. Then hydrogen chloride gas is passed through the saturated solution and the crystals of pure NaCl separate out. The soluble impurities remain in the mother liquor. The crystals are filtered, washed and dried.

1. From were Sodium chloride is obtained?
    
2. What is the nature of a common salt?
    
3. Which compounds are alkaline in aqueous medium with example?
   
   OR
   A) What happens to hydrogen cholride in water?
   B) Hydrogen chloride gas is soluble in?

Acids, bases and salts are three main categories of chemical compounds. These have certain definite properties which distinguish one class from the other.
The acids are sour in taste while bases are bitter in taste. Tasting a substance is not a good way of finding out if it is an acid or a base! Acids and bases can be better distinguished with the help of indicators. Indicators are substances that undergo a change of colour with a change of acidic, neutral or basic medium. Many of these indicators are derived from natural substances such as extracts from flower petals and barrier. Litmus, a purple dye is extracted from the lichen plant. Some indicators are prepared artificially. For example, methyl orange and phenolphthalein. Given below is a table of indicators and their colour change in acidic and basic medium.

Indicator	Colour in Acid	Colour in Alkali
Litmus	Red	Blue
Methyl	Pinkish red	Yellow
Phenolphthalein	Colourless	Pink

(i) Give two examples each of natural and artificial indicators.
(ii) An aqueous solution turns red litmus solution blue. Excess addition of which solution would reverse the change-ammonium hydroxide solution or hydrochloric acid?
(iii) What will be the change in colour when a few drops of phenolphthalein is added to a solution having pH 8.5.
or
(iv) What is universal indicator?