6 What effect does construction of buildings and roads have on percolation of water?
7 Write uses of : a) Hydrochloric Acid b) Sodium Hydroxide
8 If a compound has a formula X2Y, what are the valencies of elements X and Y?
9 What is the difference between the smallest particle of an element and a smallest particle of a compound?
10 Raju and Rakesh wanted to dilute an acid. Raju said that he will add acid to water but Rakesh said that he will add water to acid. Who is following the right procedure? Why?
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6.answer=Soil is used forconstruction of buildings and roads. It effects water percolation through cement and ultimately reduces ground waterlevel known as water label.
7.answer=(i)in the chemical industry;
in the oil processing industry;
in the pulp and paper industry;
in civil defense as a neutralizing substance;
in the food industry – to remove the skins from fruit and vegetables, in the manufacture of chocolate and cacao, and to soften olives and give them a dark color;
in cosmetics – to remove keratinized skin;
in the household
(ii)in hydrometallurgy and electrotyping;
in the chemical industry;
in the food industry as the food additive E507;
in medicine – to treat low acidity in the stomach.
8.answer=The compound formed will have the chemical formula XY3 where the valency of X is +3 due to which it would loose 3 electron to achieve the stable configuration,while that of Y is -1 due to which it readily accepts an elctron to achieve stable inert gas configuration.
These type of compound are formed by the elements of group 13
9.answer=Molecule is the smallest particleof a substance that exists independently. Molecules of mostelements are made up of only one of atom of that element. Oxygen, along with nitrogen, hydrogen, and chlorine are made up of two atoms. ... A compoundis a substance formed when two or more elementsare chemically joined.
10.answer=What happens when you add acid to water or water to acid?
A large amount of heat is released when strong acids like Sulphuric acid,HCl are mixed with water. This is mostly the case for sulfuric acid.
Commercially available sulfuric acid is dense (~1.8 g/ml) and when water is added to strong acid , a layer of hot weak acid solution is formed, which boils and sprays around. It forms extremely concentrated solution of acid initially. So much heat is released that the solution may boil very violently, splashing concentrated acid out of the container and all this because acid is exothermic and corrosive.
The reason this occurs is due to the large amount of energy released in the hydration reaction of sulfuric acid ions. Do not believe that heat comes from dissociation, as the dissociation of acids, bases, and salts always consumes energy. The energy is released from subsequent hydration. The energy released in this case will be absorbed by the small amount of water you are adding. As a result that water will splash out of the vessel carrying along with it particles of acid.
Therefore to avoid any causality we add acid to water.
When acid is poured into water, it flows down the flask and mixes much better, so no boiling occurs & the energy released due to acid water interaction is absorbed by water which is present in larger amount as compared to acid.
7.answer=(i)in the chemical industry;
in the oil processing industry;
in the pulp and paper industry;
in civil defense as a neutralizing substance;
in the food industry – to remove the skins from fruit and vegetables, in the manufacture of chocolate and cacao, and to soften olives and give them a dark color;
in cosmetics – to remove keratinized skin;
in the household
(ii)in hydrometallurgy and electrotyping;
in the chemical industry;
in the food industry as the food additive E507;
in medicine – to treat low acidity in the stomach.
8.answer=The compound formed will have the chemical formula XY3 where the valency of X is +3 due to which it would loose 3 electron to achieve the stable configuration,while that of Y is -1 due to which it readily accepts an elctron to achieve stable inert gas configuration.
These type of compound are formed by the elements of group 13
9.answer=Molecule is the smallest particleof a substance that exists independently. Molecules of mostelements are made up of only one of atom of that element. Oxygen, along with nitrogen, hydrogen, and chlorine are made up of two atoms. ... A compoundis a substance formed when two or more elementsare chemically joined.
10.answer=What happens when you add acid to water or water to acid?
A large amount of heat is released when strong acids like Sulphuric acid,HCl are mixed with water. This is mostly the case for sulfuric acid.
Commercially available sulfuric acid is dense (~1.8 g/ml) and when water is added to strong acid , a layer of hot weak acid solution is formed, which boils and sprays around. It forms extremely concentrated solution of acid initially. So much heat is released that the solution may boil very violently, splashing concentrated acid out of the container and all this because acid is exothermic and corrosive.
The reason this occurs is due to the large amount of energy released in the hydration reaction of sulfuric acid ions. Do not believe that heat comes from dissociation, as the dissociation of acids, bases, and salts always consumes energy. The energy is released from subsequent hydration. The energy released in this case will be absorbed by the small amount of water you are adding. As a result that water will splash out of the vessel carrying along with it particles of acid.
Therefore to avoid any causality we add acid to water.
When acid is poured into water, it flows down the flask and mixes much better, so no boiling occurs & the energy released due to acid water interaction is absorbed by water which is present in larger amount as compared to acid.
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