Law of Conservation of Mass
What does the law of conservation of mass state?
Matter or mass cannot be created or destroyed.
What is one sign that a chemical change has occurred?
possible responses: light, sound, temperature change, gas, color, odor, precipitate formed (solid)
What is one example of a physical change?
Any acceptable response
Possible answers: bending, crushing, cutting, melting, freezing, evaporating
What are reactants in a chemical reaction?
substances there BEFORE reaction
Is Mrs. Harrold going to Disney?
Yes
If you burn a piece of paper, what happens to the mass of the paper?
It changes into light and heat energy, ash, and gas. It is NOT destroyed.
If a substance changes color, what type of change might that indicate?
It could be either a chemical or a physical change. If a new substance is formed=chemical. If a new substance is NOT formed=physical.
How can you tell if a substance has melted?
It changed from a solid to a liquid.
What do you call the substances that are produced in a chemical reaction?
Products
How many dogs does Mrs. Harrold have?
2
How does the law of conservation of mass apply during a chemical reaction?
The mass of the reactants will always equal the mass of the products.
Describe what happens when vinegar is mixed with baking soda.
The vinegar reacts with the baking soda to form a gas.
What happens to the molecules in a solid when it becomes a liquid?
They move faster.
In the reaction A+B→C+D, identify the reactants and products.
A, B= reactants
C, D= Products
What are the names of Mrs. Harrold's children?
Jack, Lillian
Can mass be created or destroyed? Explain.
No- mass cannot be created or destroyed. It will be transformed into new substances or released as a form of energy.
What is meant by the term "gas production" in the context of a chemical change?
bubbles are formed
Describe how a physical change is different from a chemical change?
Physical change- NO new substance is formed. Size/shape may be changed. Molecules remain the same.
Chemical Change- bonds between atoms are broken, atoms rearrange and form NEW substances with NEW chemical properties.
How does the arrangement of atoms change from reactants to products in a chemical reaction?
How long has Mrs. Harrold been teaching?
18 years
Give an example of a real-life situation where you can see the law of conservation of mass in action.
Any acceptable response.
How can temperature change indicate a chemical change?
Exothermic= feels hot/releases heat
Endothermic= feels cold/absorbs heat
Can a physical change be reversed? Provide one example.
Yes- Salt dissolved in water can be removed through evaporation.
Explain how the atoms in the reactants compares to the atoms in the products. *Law of Conservation of Mass
The number and type of atoms in the reactants is the SAME as the number and type of atoms in the products. They have just be rearranged.
ex:
2HCl + Zn --> ZnCl2 + H2
Name the other state where Mrs. Harrold taught
Virginia