The Law of Conservation of Mass

Which of the following models best demonstrates a balanced chemical equation?

• F
• G
• H
• J

Tags

NGSS.HS-PS1-7

Which of the following equations demonstrates an actual chemical reaction that forms a new substance?

• A
• B
• C
• D

Tags

NGSS.HS-PS1-2

What does the principle of conservation of mass mean?

• Matter is not created or destroyed.
• The total mass of the reactants is greater than the total mass of the products.
• The total mass of the reactants is less than the total mass of the products.
• Matter is not changed.

Tags

NGSS.HS-PS1-7

All of the following reactions are correctly balanced except-

• A
• B
• C
• D

Tags

NGSS.HS-PS1-7

What is the mass of H₂O in the reaction above?

• 70.01
• 24.11
• 21.44
• 48.22

Tags

NGSS.HS-PS1-7

Balance this equation:
 2Li + Cl₂ -> LiCl

• 2Li + Cl₂ -> 4LiCl₂
• 2Li + Cl₂ -> LiCl₂
• 2Li + Cl₂ -> 2LiCl
• Li + Cl₂ -> 2LiCl

Is this equation balanced?

• yes
• no
• not enough information
• Left side is balanced

Tags

NGSS.HS-PS1-7

A chemical reaction produces two new substances, and each product has a mass of 25 grams. What was the total mass of the reactants?

• 25 grams 
• 50 grams
• 75 grams 
• 100 grams 

Tags

NGSS.HS-PS1-7

Balance this equation
_N₂ + _H₂ --> _NH₃

• 1,2,3
• 1,3,2
• 1,1,2
• 2,1,1

Chemical X has a mass of 5 grams, and chemical Y has a mass of 10 grams. If the two chemicals are mixed and a complete chemical reaction takes place, what is most likely the mass of the product? 

• 5 grams
• 10 grams
• 15 grams
• 50 grams

Tags

NGSS.HS-PS1-7