Physical and Chemical Changes, Law of Conservation of Matter

Law of conservation of mass states that 

• matter is created
• matter is destroyed
• matter is neither created nor destroyed
• matter does not change

Tags

NGSS.MS-PS1-5

True or false.  Law of conservation of mass means that the number of atoms of the products is more than the number of atoms in the reactants. 

• True
• False

Tags

NGSS.MS-PS1-5

Bob puts 200 grams of ice into a pitcher with 900 grams of water. He gets distracted and comes back later to find that the ice has melted in the water. How many grams of water does Bob now have in the pitcher?

• 200 g
• 700 g
• 1,100 g

Tags

NGSS.MS-PS1-5

What is the law of conservation of mass?

• The amount of matter changes when reacted or changed.
• The mass of all reactants are changed during a physical or chemical change
• The mass of the reactants equals the mass of the products
• The mass of the products is different than the mass of the reactants.

Tags

NGSS.MS-PS1-5

Suppose a reaction were to happen in an open container in a lab.  During the reaction, the scientist observes the chemicals bubble, and produce a gas.   During the analysis the scientist notices that the reactants weighed 20 g when he started, and the product weighed 18 g.  Explain what happened.  

• His chemical reaction defied the law of conservation of mass
• The product destroyed mass during the reaction
• The reactants created matter during the reaction
• The gas that was produced was not able to be weighed since the container was open.  

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

If reaction starts with 20g of reactants it should produce... 

• a total of 40g of product
• a total of 10g of product
• a total of 80 g of product
• a total of 20g of product

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

10g of white powder reacts with 10g of clear liquid. The reaction bubbles and changes color producing a black liquid that has a mass of 13g. What can be concluded?

• 5g of gas was produced
• This experiment violates the conservation of mass
• 7g of gas was produced
• The excess reactant is destroyed & disappears during the reaction

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

How many nitrogen atoms does NH₃ have?

• 1
• 2
• 3
• 4

Tags

NGSS.MS-PS1-1

What are the REACTANTS :
H₂O + CO₂ → HCO + HO

• H₂O and CO₂
• HCO and HO
• H₂O ONLY
• HCO ONLY

Tags

NGSS.MS-PS1-1

REACTANTS are always on what side of the chemical equation?

• right
• left
• top
• bottom