Physical and Chemical Changes

Complete the sentences below.

 

A change in which no new substances are formed is called a __________ change.

 

A change in which new substances are formed is called a ___________ change.

Tags

NGSS.MS-PS1-4

Which of the following statement(s) is/are true about chemical changes? You may select more than one statement.

• New substance(s) is/are formed.

• The substances that react with one another are known as the “products”.

• Chemical changes are usually not reversible.

• Energy may be taken in or given out during chemical changes.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

In a chemical reaction, the substances that react with each other are called the _____ . The new substances that are formed are called the _____ .

• products; reactants

• reactants; products

Tags

NGSS.MS-PS1-5

• carbon dioxide

• glucose

• oxygen

• water

Tags

NGSS.MS-LS1-7

Write a word equation for the chemical reaction described by the statement below.

 

Zinc burns in oxygen to form a solid called zinc oxide.

Tags

NGSS.MS-PS1-2

Which of the following statements about all chemical reactions is true? 

• Atoms are lost in a chemical reaction.

• Atoms are formed in a chemical reaction.

• A chemical reaction involves the rearrangement of atoms to form products.

• Mass is not conserved in a chemical reaction. 

Answer explanation

During a chemical reaction, atoms of the reactants rearrange themselves and combine chemically to form products. No atoms are lost or formed in a chemical reaction. Thus, the mass of the reactants is equal to the mass of the products. Mass is conserved during a chemical reaction.

Tags

NGSS.MS-PS1-5

Which of the following statements correctly describes combustion?

• Combustion is a chemical change in which a substance is heated in the presence of carbon dioxide.

• Combustion is a physical change in which a substance is heated in the presence of carbon dioxide.

• Combustion is a chemical change in which a substance is heated in the presence of oxygen.

• Combustion is a physical change in which a substance is heated in the presence of oxygen.

Answer explanation

Combustion is a chemical change in which a substance is heated in the presence of oxygen.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Calcium carbonate undergoes thermal decomposition to form calcium oxide and carbon dioxide gas.

Write a word equation to represent the thermal decomposition of calcium carbonate.

Answer explanation

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-1

Explain why heating a metal sphere is considered a physical change and not a chemical change.

Answer explanation

This is a physical change as no new substances are formed. The metal sphere expands.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Tabulate the differences between a physical and a chemical change.

Answer explanation

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4