Signs of Chemical Reactions

A change in the shape of an object is an example of _________________.

• a chemical change

• energy

• an endothermic change

• a physical change

Rohan, Mason, and Samuel are having the time of their lives in their science class, witnessing a fascinating chemical reaction. They are on the edge of their seats, eager to determine if a chemical reaction has truly taken place. They understand that a chemical reaction has occurred if:

• a new solid, known as a precipitate, is formed.

• there is a noticeable change in color.

• there is a shift in temperature.

• All of these answers are valid indicators of a chemical reaction.

Tags

S8P1

You have 2 chemicals, CHEMICAL A and CHEMICAL B. They are both liquids. When you combine them you notice some crystals starting to form within them. Did a chemical reaction occur?

• Yes

• No

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which example is a chemical change?

• baking powder fizzing

• ice melting

• water boiling

• sugar cube dissolving

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

How is a chemical change different from a physical change?

• there is no difference

• a physical change creates a new substance

• a chemical change creates a new substance

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of the following describes a precipitate?

• a liquid forms when a block of metal is heated
• a solid forms when one liquid is poured into another
• a gas forms when a solid is placed in a liquid
• bubbles form when an acid is poured on a rock

Tags

NGSS.MS-PS1-2

When vinegar and baking soda are combined, bubbles and foam are produced.

What evidence demonstrates that a chemical change has occurred?

• A color change occurs.

• A gas is formed.

• A solid is dissolved.

• A precipitate is formed.

Tags

NGSS.MS-PS1-2

Which scientific observation, shown in the chart, indicates that a chemical reaction has NOT occurred?

• Number 1

• Number 2

• Number 3

• Number 4

Tags

112.27.b.6.C

What is a chemical reaction?

• a change in matter when the molecules rearrange to make new molecules

• a change in matter when matter changes its form or appearance

• a change in matter when the physical appearance changes

• a very boring change in matter

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Ethan, Luna, and Harper were having a science experiment party! They noticed several interesting things happening during their experiments. Which of the following observations would NOT indicate that a chemical reaction has occurred?

• Ethan noticed a change in temperature in one of his experiments

• Luna saw the formation of a precipitate in her test tube

• Harper observed the emission of light from one of her mixtures

• They mixed two substances together, but nothing else seemed to change

Tags

NGSS.MS-PS1-2