Chemistry 1010

Physical vs Chemical Change

Physical Change:

A physical change does not involve changing the identity of the substance involved. For example, when we break a branch into two pieces before throwing the pieces into a bonfire, this process does nothing to change the nature or properties of the branch.

Chemical Change:

Once you throw the branch into the bonfire, it will burn and this will produce ash, carbon dioxide, and water. These are new substances with properties different from those of the branch. Whenever we end up with materials different from what we started, we are dealing with a chemical change.

Physical Change

Physical Changes:

• slicing bread - a change in the shape
• raking leaves - a change in the shape
• brewing coffee - a change in state (solid to solution)
• melting ice - a change of state (solid to liquid) 

Chemical Changes:

• baking bread - a change from dough to textured solid
• burning leaves - a change from leaves to ashes
• mixing yeast, sugar, and water - a change involving gas production
• exploding fireworks - a change resulting in high pressure gas (which causes the explosion)

Physical Change

Physical Changes:

• breaking glass - a change in the shape
• mow the lawn - a change in the shape
• squeeze orange for juice - a  separation of pulp and liquid
• mix lemonade into water - a change of state (solid to solution)

 Chemical Changes:

• fry an egg - a change in protein structure showing in both texture and color
• burn toast - a change due to combustion in both texture and color
• bleach your hair - a change in protein shown in both texture and color
• rusting nail - a change in metal to oxidized metal showing in both texture and color

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