Unit 4 Lesson 4

Conservation of Mass

• Can't create or destroy matter
• Mass (# of atoms) and weight (force of gravity) are different
• Gases have mass

If one of the products of a chemical reaction is a gas, the mass of the products will be less than the mass of the reactants, unless you trap the gas.

Mass Change

• Individual atoms are conserved in chemical reactions and physical changes. The number of atoms of each element remains the same from start to finish.
• Mass is conserved in chemical reactions. The total mass of the products equals the total mass of the reactants.

Practice Problems
4) when an ice cube melts, what quantity changes? C- its volume
7) trap the gas and ash left and weigh it.

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