Law of Conservation of Mass

Which is Chemical Equation is Balanced?

• CH₄+O₂------CO₂+2H₂O
• H₂+O₂-----2H₂O₄
• 4Al+3O₂-----2Al₂O₃

B₂ + 3W₂ => 2BW₃

• Balanced
• Unbalanced

Which are chemical changes

• Iron rusting 
• Glass breaking
• Clothing ripping
• Hair cut

What is the law of conservation of mass?

• The part of the universe being studied
• The rest of the universe that interacts with the system
• Within a closed system, mass does not change
• A system that freely exchanges matter and energy

System

• The part of the universe being studied
• The rest of the universe that interacts with the system
• Within a closed system, mass does not change
• A system that freely exchanges matter and energy

Surroundings

• The part of the universe being studied
• The rest of the universe that interacts with the system
• Within a closed system, mass does not change
• A system that freely exchanges matter and energy

Molecule

• A group of atoms bonded together
• Basic unit of a chemical element
• Coefficient
• Subscript

A system that only exchanges energy with its surroundings; mass is conserved.

• Open System
• Closed System

Can matter be created or destroyed?

• Yes, it can be created.
• Yes, it can be destroyed.
• No, matter is always conserved
• None of these

The mass after a physical change, such as ice melting into water, stays the same

• True
• False