Chemical Reactions and Equations Science - Chemical Reactions and Equations

Fill in the following blanks with suitable words:
Anti-oxidants are often added to fat containing foods to prevent __________ due to oxidation.

Fill in the following blanks with suitable words:A solution made in water is known as an __________ solution and indicated by the symbol __________.

Fill in the following blanks with suitable words:
The addition of oxygen to a substance is called __________ whereas removal of oxygen is called __________.

Fill in the following blanks with suitable words:
The addition of hydrogen to a substance is called __________ whereas removal of hydrogen is called __________.

State whether the following statement is true or false:
A chemical equation can be balanced easily by altering the formula of a reactant or product.

Potassium metal reacts with water to give potassium hydroxide and hydrogen gas. Write a balanced chemical equation for this reaction.

Give one example of a combination reaction which is also exothermic.

Ammonia reacts with oxygen to form nitrogen and water. Write a balanced chemical equation for this reaction. Add the state symbols for all the reactants and products.

Explain the term “rancidity”. What damage is caused by rancidity?

Express the following facts in the form of a balanced chemical equation:“When a strip of copper metal is placed in a solution of silver nitrate, metallic silver is precipitated and a solution containing copper nitrate is formed”.

Give one example of an exothermic reaction and one of an endothermic reaction.

Why are decomposition reactions called the opposite of combination reactions ? Explain with equations of these reactions.

Explain the term “corrosion” with an example. Write a chemical equation to show the process of corrosion of iron.

What do you mean by a precipitation reaction? Explain giving an example.

What is the difference between displacement and double displacement reactions? aWrite equations for these reactions.

A colourless lead salt, when heated, produces a yellow residue and brown fumes:

1. Name the lead salt.
2. Name the brown fumes.
3. Write a chemical equation of the reaction involved.

Define the following in terms of gain or loss of hydrogen with one example:

1. Oxidation.
2. Reduction.

The metal M reacts vigorously with water to form a solution S and a gas G. The solution S turns red litmus to blue whereas gas G, which is lighter than air, burns with a pop sound. Metal M has a low melting point and it is used as a coolant in nuclear reactors.

1. What is metal M?
2. What is solution S? Is it acidic or alkaline?
3. What is gas G?
4. Write a balanced chemical equation for the reaction which takes place when metal M reacts with water.
5. Is this reaction exothermic or endothermic?

Gas A, which is the major cause of global warming, combines with hydrogen oxide B in nature in the presence of an environmental factor C and a green material D to form a six carbon organic compounds E and a gas F. The gas F is necessary for breathing.

1. What is gas A?
2. What is the common name of B?
3. What do you think could be C?
4. What is material D? Where is it found?
5. Name the organic compound E.
6. What is gas F? Name the natural process during which it is released.

When water is added gradually to a white solid X, a hissing sound is heard and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during white washing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory.

1. What could be solid X? Write its chemical formula.
2. What could be product Y? Write its chemical formula.
3. What is the common name of the solution of Y which is used for testing carbon dioxide gas?
4. Write chemical equation of the reaction which takes place on adding water to slid X.
5. Which characteristic of chemical reactions is illustrated by this example?

A solid substance P which is very hard is used in the construction of many buildings, especially flooring. When substance P is heated strongly, it decomposes to form another solid Q and a gas R is given out. Solid Q reacts with water with the release of a lot of heat to form a substance S. When gas R is passed into a clear solution of substance S, then a white precipitate of substance T is formed. The substance T has the same chemical composition as starting substance P.

1. What is substance P? Write its common name as well as chemical formula.
2. What is substance Q?
3. What is gas R?
4. What is substance S? What is its clear solution known as?
5. What is substance T? Name any two natural forms in which substance T occurs in nature.

When metal X is treated with a dilute acid Y, then a gas Z is evolved which burns readily by making a little explosion.

1. Name any two metals which can behave like metal X.
2. Name any two acids which can behave like acid Y.
3. Name the gas Z.
4. Is the gas Z lighter than or heavier than air?
5. Is the reaction between metal X and dilute acid Y, exothermic or endothermic?
6. By taking a specific example of metal X and dilute acid Y, write a balanced chemical equation for the reaction which takes place. Also indicate physical states of all the reactants and products.