Chemical reactions

Question 1

What is a chemical reaction

Answer 1

Then one or more substances undergo a chemical change, the absorption or release of energy so as to form one or more products then the changes taking place collectively are called chemical change.

Question 2

What is chemical equations

Answer 2

A chemical equation is symbolic representation of a chemical reaction.

Question 3

What is a balance equation

Answer 3

The equation in which the number of atoms of each element is the same on both sides of the reactants and the product is called a balanced equation.

Question 4

Why is a chemical equation balanced

Answer 4

A chemical equation is balanced and satisfying fulfill the law of conservation of mass. The law states that during chemical reaction, atoms are neither created nor destroyed, they are only rearranged.

Question 5

Information convened by a balanced equation.

Answer 5

1. This substance which react and the products formed by the chemical reaction.
2. The symbols are formula of all the substances involved in a chemical reaction.
3. Number of atoms or molecules are for substances involved in a chemical reaction.
4. Weights of all substances involved in a chemical reaction.

Question 6

Define a skeletal chemical equation.

Answer 6

Any question is set to be unbalanced for masses not same on both sides of the equation who stops such an equation is called a skeletal chemical equation for a reaction.

Question 7

How to determine whether a chemical reaction has taken place

Answer 7

1. Changes in state
2. Change in color
3. Evolution of gas.
4. Change in temperature.
5. Formation of precipitate.

Question 8

how to make reactions more informative

Answer 8

1. by indicating the physical state of the reactants and the products
2. By indicating the heat changes taking place in the reaction.
3. By indicating conditions under which reactions take place

Question 9

Combination reaction takes place between

Answer 9

1. Two or more elements
2. Two a more compounds.
3. Elements and compounds

Question 10

Examples of combination reactions

Answer 10

1. Burning of coal

2. Formation of water

Question 11

Define endothermic reactions

Answer 11

The reactions in which energy is absorbed with the formation of products are called endothermic reactions

Question 12

Define exothermic reaction

Answer 12

Reactions in which heat is released along with the formation of products is called exothermic reaction

Question 13

Define combination reactions

Answer 13

The reaction in which two or more substances (elements or compounds) are combined to form a single substance under suitable conditions.

Question 14

Define decomposition reaction

Answer 14

The reaction in which a single substance splits into two or more substances under suitable conditions.

Question 15

Types of decomposition reactions.

Answer 15

1. Thermal decomposition
2. Electro decomposition
3. Photo decomposition

Question 16

How to check if oxygen is released after the chemical reaction.

Answer 16

To check if oxygen is released after chemical reaction they can ignite a splinter and put it off then bring it over the mouth of the test tube and it’ll reignite

Question 17

In electrolysis of water which gas is present in cathode and anode.

Answer 17

• in cathode it’s hydrogen gas.

- in an old it’s oxygen gas.

Question 18

Define displacement reaction

Answer 18

Reactions in which of one element takes place of another element in compound are known as displacement reaction.

Question 19

Define double displacement reaction

Answer 19

Reactions in which two compounds react by exchange of ions to form two new compounds are called double displacement reaction.

Question 20

Types of double displacement reactions.

Answer 20

1. Precipitation reaction: - air reaction that produces a precipitate can be called precipitation reactions.
2. Neutralization reaction: - when acid combines with base it reacts to give salt and water.