Chemical Reactions Unit

Which of the following is a chemical change rather than a physical change 

• boiling water at 100 C
• chopping up a piece of wood. 
• cooking a cake 
• ice carbon dioxide sublimating to gas 

The process going from a gas to a liquid is called ...

• evaporation 
• melting 
• condensation 
• sublimation 

A Precipitate forms 

• when a gas is bubble through a liquid 
• a lighter taper causes a gas to burn 
• in a liquid or gas  after a reaction and causes cloudiness (caused by a solid forming) 

a copper penny turning greenish after a few years.

• Chemical Change
• Physical Change

An gel ice pack getting cold after you put it in the freezer for an hour.

• Chemical Change
• Physical Change

Which of the following IS a physical change?

• Getting a haircut
• Rusty metal
• sour milk
• A compound

According to the law of conservation of mass, matter cannot be created or ________

True or False: In a complete chemical equation, there must be the same number of atoms of each element on the reactants and products side.

• True

• False

A chemical change is different than a physical change because in a chemical change

• chemicals are used

• molecules do not physically touch

• a new substance is formed and in a physical no new substance is formed

• the change can be seen but in a physical change it cannot

Which of the following 2 are chemical reactions?

• sugar dissolving in water

• water turning into steam

• burning wood

• mixing baking soda and vinegar

• tearing paper