Chemical reaction

Which of the following are signs of a chemical reaction?

• Formation of a gas

• A change in temperature

• A change in color

• A change in size

In a chemical reaction, the number of atoms in the reactants and the products...

• Must be the same

• Must be different

What is the density of water?

• 1g/mL

• 3g/mL

• 7g/mL

• 2.3g/mL

Which of these is NOT a sign of a chemical reaction?

• A phase change

• Formation of a precipitate

• A color change

• A temperature change

When a chemical reaction occurs...

• New molecules and atoms are formed

• Molecules and atoms are rearranged

• Molecules and atoms disappear

• Molecules and atoms are destroyed

Is the chemical equation here balanced?

• Yes

• No

Imagine you have an unknown substance in your hand. You know that it has a mass of 100g and a volume of 10cm3. What is the density of this unknown substance?

• 5g/cm3

• 11g/cm3

• 10g/cm3

• 25g/cm3

In a cup you have 50g of water. This means you have how many mL's of water?

Remember: water has a density of 1g/mL.

• 10mL

• 74mL

• 100mL

• 50mL

A pure substance is made of how many different types of atoms/molecules?

• 4

• 3

• 1

• 2

A mixture is made of at least how many different types of atoms/molecules?

• 2

• 1

• 4

• 7