07-12-2012, 06:20 PM
CHEMICAL REACTIONS
[attachment=43025]
Why should a magnesium ribbon be cleaned before it is burnt in air?
Magnesium is an extremely reactive metal. When stored, it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide is quite stable and prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned by sand paper for removing this layer so that the underlying metal can be exposed to air.
What is a balanced chemical equation? Why should chemical equations be balanced?
A reaction which has an equal number of atoms of all the elements on both sides of the chemical equation is called a balanced chemical equation.
The law of conservation of mass states that mass can neither be created nor destroyed. Hence, in a chemical reaction, the total mass of reactants should be equal to the total mass of the products. It means that the total number of atoms of each element should be equal on both sides of a chemical equation. Hence, it is for this reason that chemical equations should be balanced.
Why do we apply paint on iron articles?
Iron articles are painted because it prevents them from rusting. When painted, the contact of iron articles from moisture and air is cut off.Hence, rusting is prevented. So presence of air and moisture is essential for rusting to take place.
Oil and fat containing food items are flushed with nitrogen. Why?
Nitrogen is an inert gas and does not easily react with these substances. On the other hand, oxygen reacts with food substances and makes them rancid. Thus, bags used in packing food items are flushed with nitrogen gas to remove oxygen inside the pack. When oxygen is not present inside the pack, rancidity of oil and fat containing food items is avoided.
[attachment=43025]
Why should a magnesium ribbon be cleaned before it is burnt in air?
Magnesium is an extremely reactive metal. When stored, it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide is quite stable and prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned by sand paper for removing this layer so that the underlying metal can be exposed to air.
What is a balanced chemical equation? Why should chemical equations be balanced?
A reaction which has an equal number of atoms of all the elements on both sides of the chemical equation is called a balanced chemical equation.
The law of conservation of mass states that mass can neither be created nor destroyed. Hence, in a chemical reaction, the total mass of reactants should be equal to the total mass of the products. It means that the total number of atoms of each element should be equal on both sides of a chemical equation. Hence, it is for this reason that chemical equations should be balanced.
Why do we apply paint on iron articles?
Iron articles are painted because it prevents them from rusting. When painted, the contact of iron articles from moisture and air is cut off.Hence, rusting is prevented. So presence of air and moisture is essential for rusting to take place.
Oil and fat containing food items are flushed with nitrogen. Why?
Nitrogen is an inert gas and does not easily react with these substances. On the other hand, oxygen reacts with food substances and makes them rancid. Thus, bags used in packing food items are flushed with nitrogen gas to remove oxygen inside the pack. When oxygen is not present inside the pack, rancidity of oil and fat containing food items is avoided.