Chemical Reactions

How do you know if a chemical reaction has occurred?

• One substance sinks to the bottom

• The two substances remain mixed together

• One substance dissolves in the other

• Gas bubbles are produced

Which of the following statements are true about heating up sugar?

• A chemical reaction did occur because a new substance was formed.

• A chemical reaction did not occur.

• The density of the substance changed and bubbles were produced.

• A chemical reaction did not occur because the color of the sugar did not change.

C6h12o6 + 6O2 --> 6CO2 + 6H2O

The total number of carbon, hydrogen, and oxygen atoms _______ after the reaction.

• increase

• decrease

• remain the same

• changes

When the amount of atoms stay the same after a reaction it is because of...

• the law of conservation of matter

• cell theory

• law of attraction

• theory of evolution

CaCl2 + Na2SO4 --> CaSO4 + 2NaCl

The Law of Conservation of Mass is supported because the number of Ca, Cl, NA, S and O atoms on the reactant side _____ the number of Ca, Cl, Na, S and O on the product side.

• does not equal

• equals

• is greater

• is less than

Is this a chemical or physical change?

CH4 + 2O2 --> CO2 + 2H2O

• Chemical

• Physical

Which type of material would be least likely to burn you?

• a handle made of plastic

• a handle made of wood

• a handle made of aluminum foil

• a handle made of copper

A chemical reaction that absorbs energy is called a ______ reaction.

• endothermic

• synthesis

• exothermic

• decomposition

What side of a chemical reaction is the product found on?

• left

• middle

• right

Condensation formation is an example of which change?

• Chemical

• Psychical