Characteristics of Chemical Reactions

Hydrogen and oxygen react to form water. At an atomic level, how do we know that a chemical reaction has occurred?

• Hydrogen molecules are negative, and oxygen positive

• For every oxygen atom, two hydrogen atoms are needed

• The hydrogen and oxygen atoms regroup into a new molecule

• Oxygen atoms are much larger than hydrogen atoms

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of the following statements is true?

• We know combining Substances A and B resulted in a chemical reaction because a gas was formed

• We know combining Substances C and D resulted in a chemical reaction because of the lack of a temperature change

• We know combining Substances A and B resulted in a chemical reaction because of the lack of a temperature change

• We know combining Substances A and B resulted in a chemical reaction because of the lack of a temperature change

Tags

NGSS.MS-PS1-2

Which of the following is the best description of the results of a chemical reaction?

• A new substance with different properties is formed

• The substance seems to disappear after dissolving in water

• The substance changes from liquid to solid at a low temperature

• The reaction can be reversed to get back the original substance

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Rust forming on a piece of iron is an example of which of the following:

• A physical change because the process can be reversed

• A chemical change because oxygen atoms from the atmosphere bonded with the iron atoms

• The natural process of decay as metallic ions age

• A violation of the laws of physics because new mass has been created

Tags

NGSS.MS-PS1-5

Which of the following statements is true?

• Cutting paper is an example of a chemical reaction because a new substance is formed and the process cannot be undone

• Freezing water is an example of a chemical reaction because a new substance is formed and the process cannot be undone

• Melting ice is an example of a chemical reaction because a new substance is formed and the process cannot be undone

• Burning paper is an example of a chemical reaction because a new substance is formed and the process cannot be undone

Tags

NGSS.MS-PS1-2

Hint: gas bubbles are being produced. Chemical reaction or not?

• yes

• no

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Chemical reaction or not?

• yes

• no

Tags

NGSS.MS-PS1-2

Chemical reaction or not?

• yes

• no

Tags

NGSS.MS-PS1-2

Glow stick has been cracked. Chemical reaction or not?

• yes

• no

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Hint: Bike is rusting. Is this a chemical reaction?

• yes

• no

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5