Crystals of Salts

Q.

How Would You Balance The Following Equation:${\mathrm{CH}}_4+{\mathrm{O}}_2\to {\mathrm{CO}}_2+{\mathrm{H}}_2\mathrm{O}$

Q.

How is Gypsum different from Plaster of Paris?

Q.

Give reasons for the following:

On strong heating, blue-coloured copper sulphate crystals turn white.

Q.

When a black metal compound XO is heated with a colourless gas $Y_2$, then metal X and another compound $Y_{2}O$ are formed. Metal X is red-brown in colour which does not react with dilute acids at all. Gas $Y_2$ can be prepared by the action of a dilute acid on any active metal. The compound $Y_{2}O$ is a liquid at room temperature which can turn anhydrous copper sulphate blue.

(a) what do you think is metal X ?

(b) What could be gas $Y_2$ ?

(c) What is compound XO ?

(d) What is compound $Y_{2}O$

(e) Write the chemical equation of the reaction which takes place on heating XO with $Y_2$.

(f) What type of chemical reaction is illustrated in the above equation ?

Q.

What happens when a mixture of ${\mathrm{Cu}}_2\mathrm{O}$ and ${\mathrm{Cu}}_2\mathrm{S}$ is heated?

Q.

(a) What happens when copper sulphate crystals are heated strongly? Explain with help of an equation.

(b) What happens when a few drops of water are added to anhydrous copper sulphate? Explain with the help of an equation.

Q.

How is the concentration of hydroxide ions $\left({\mathrm{OH}}^{-}\right)$ affected when excess base is dissolved in a solution of Sodium hydroxide?

Q. Which of the following compounds contain water of crystallisation?

1. Common salt
2. Gypsum
3. Plaster of paris
4. Washing soda

Q.

How is washing soda prepared from sodium carbonate(${\mathrm{Na}}_2{\mathrm{CO}}_3$)? Give its chemical equation. State the type of this salt. Name the type of hardness of water which can be removed by it?

Q.

Name a salt which does not contain water of crystallisation

Q.

How many molecules of water of crystallisation (per formula unit) are present in :

(a) copper sulphate crystals ?

(b) washing soda ?

(c) gypsum ?

Q.

Write the chemical equation that represents the reaction between Carbon and Oxygen that produces Carbon dioxide?

Q.

Which of the following are efflorescent substances?

1. ${\mathrm{Na}}_2{\mathrm{CO}}_3.10{\mathrm{H}}_2\mathrm{O}$

2. ${\mathrm{CuSO}}_{4}5{\mathrm{H}}_2\mathrm{O}$

3. ${\mathrm{K}}_2{\mathrm{SO}}_4.{\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3.24{\mathrm{H}}_2\mathrm{O}$

4. Both A and B

Q.

List the composition of aerated drinks.

Q.

Number of water molecules present in one formula unit of a salt is called__.

1. water of hydration

2. water of crystallisation

3. evaporated water

4. solid water

Q.

An experiment showed that in a lead chloride solution, 6.21 g of lead combined with 4.26 g of chlorine.

What is the empirical formula of this chloride? [Pb = 207, Cl = 35.5]

1. PbCl₂

2. PbCl₄

3. PbCl₃

4. PbCl₆

Q. Name the substance that remains in a test tube aftr heating ferrous sulphate.

Q.

The number of molecules of water of crystallisation present in washing soda crystals is :

(a) five

(b) two

(c) ten

(d) seven

Q.

Give the chemical equation for the formation of sodium hydride.

Q.

What is the difference between Gypsum and Plaster of Paris ?

Q.

What is the color of Aluminium Sulfate when it is added to water?

Q.

5g of crystalline salt rendered anhydrous; lost 1.8g of water. The formula weight of the anhydrous salts is 160. The number of water molecules of crystallization is:

1. 1

2. 2

3. 3

4. 5

Q.

Explain why :

(a) It is necessary to find out the ration of reactants required in the preparation of sodium sulphate,

(b) Fused calcium chloride is used in the preparation of $FeC{l}_3$?

(c) Anhydrous $FeC{l}_3$ cannot be prepared by heating hydrated Iron (III) chloride.

Q.

Answer the question below, relating your answers only to salts in the following list : Sodium chloride, anhydrous calicum chloride, copper sulphate-5-water ?

(a) What name is given to the water in the compound copper sulphate-5-water ?

(b) If copper sulphate-5-water is heated, anhydrous copper sulphate is formed. What is its colour ?

(c) By what means, other than heating, could you dehydrate copper sulphate-5-water and obtain anhydrous copper sulphate ?

(d) Which one of the salts in the given list is deliquescent ?

Q.

Silver coins turn black when exposed to air. Explain using a balanced chemical equation.

Q.

The metal salt A is blue in colour. When salt A is heated strongly over a burner, then a substance B is eliminated and a white powder C is left behind. When a few drops of a liquid D are added to powder C, it becomes blue again. What could be A, B, C and D?

Q. What is meant by water of crystallization of a substance? Describe an activity to show the water of crystallization.

Q.

Why is the residue on the filter paper washed with distilled water in the separation of the sand and salt mixture?

Q.

Whats the difference between Plaster and Plaster of Paris?

Q.

State your observations when following salts are heated strongly in dry state. Write chemical equations in support of your answer.

Ammonium chloride $\left({\mathrm{NH}}_4\mathrm{Cl}\right)$