Chemical Reactions Lesson 3

Which of the following is an example of a chemical reaction?

• Water evaporating from a pot on a hot stove
• Sand being removed from sea water by filtration
• A spoonful of sugar dissolving in a glass of water
• A white solid forming when two clear liquids are poured together
  

Which of the following is an example of a chemical reaction?

• A marshmallow turning black when heated over a fire
• A powder dissolving in water to make lemonade
• An ice cube melting into a puddle of water
• Salt crystals being crushed into a powder
  

What happens when chemical bonds break and new bonds form?

• a physical reactions

• a chemical reaction

• matter is destroyed

• surface area increases

CaCO₃ represents a chemical _______________.

• Symbol

• Formula

• Subscript

• Reaction

The only sure evidence for a chemical reaction is ...

• the formation of a gas.

• a color change.

• the production of one or more new substances.

• bubbling or fizzing

The substances listed on the left side of a chemical equation are the _____________.

• products

• coefficients

• precipitates

• reactants

In chemical reactions, what does the Law 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.

A chemical reaction that absorbs energy in the form of heat is described as

• endothermic
• exothermic
• combustion
• unbalanced

When heated, oxygen reacts with copper to form copper oxide:
If this reaction occurs in a sealed container, will the mass of the container and everything in it increase, decrease, or stay the same and why?

• The mass will stay the same because the number of each kind of atom stays the same.
• The mass will increase because a new kind of molecule is formed.
• The mass will decrease because two substances combine to form one substance.
• More information is needed to tell if the mass will change.
  

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What type of reaction is occurring in the diagram? Which response below explains the reason for that type of reaction?

• Exothermic - heat is released when the candle burns.

• Endothermic - heat is released when the candle burns.

• Exothermic - heat is taken in when the candle burns.

• Endothermic - heat is taken in when the candle burns.