Evidence of a Chemical Reaction

Which of the following characteristics is shared by all chemical reactions?

• Produce a precipitate

• Show a color change

• Release heat energy

• Form new substances

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NGSS.MS-PS1-2

NGSS.MS-PS1-5

When there is a precipitate formed in a solution it is evidence of__________.

• Rain

• A physical change

• A chemical reaction

• What's evidence?

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NGSS.MS-PS1-2

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Do the ending substances (or products) in this example have different properties after the change?

• Yes

• No

• Uhh, sure??

Answer explanation

Yes, water has different properties than any of the reactants.

Tags

NGSS.MS-PS1-2

This is a (a)   change

Answer explanation

This is a chemical change because it results in the formation of new substances

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Do the properties of the starting substances (or reactants) change?

• Yes

• No

• uhh, maybe?

Answer explanation

Yes, they combine to form water, which has different properties than hydrogen or oxygen.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What is it called when a solid (clouds) form in a liquid?

• A color change

• A precipitate

• Temperature change

• Gas formation

Tags

NGSS.MS-PS1-2

What are the starting substances (reactants) in this equation?

• Two aqueous solutions   

• cloudy substance 

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What part of the equation has a greater mass?

• Reactants

• Products

• Neither, they are both the same.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

You know that a chemical reaction has occurred if

• there is a precipitate (new solid)

• there is a color change.

• there is a temperature change.

• All of these answers are evidence.

Tags

NGSS.MS-PS1-2

A teacher shows the class two liquids that are both odorless and clear. When they mix together, solid gold chunks are formed. What change occurred and how do you know?

• A chemical change because a precipitate was formed

• A physical change because there was a color change

• A chemical change because an odor was produced

• A physical change because the volume increased when the two liquids were mixed together.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5