Your SlideShare is downloading. ×
Chemical and physical changes - introduction notes
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Chemical and physical changes - introduction notes

199

Published on

Chemical and physical changes introduction notes

Chemical and physical changes introduction notes

Published in: Education, Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
199
On Slideshare
0
From Embeds
0
Number of Embeds
5
Actions
Shares
0
Downloads
4
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Physical Changes and Chemical Changes
  • 2. Physical Changes A physical change is when a substance changes, but remains the same substance.  Change in size.  If a piece of paper is cut into two pieces, the paper becomes smaller, but still remains as paper.  Change in shape.  A tree is carved into a baseball bat. The wood changes shape, but still remains as wood.  Change in state.  H2O as liquid water freezes and changes into solid ice. The H2O changes state from a liquid to a solid, but still remains H2O.
  • 3. More about changes of state…four states.  The four states of mater are solid, liquid, gas, plasma.  A solid has a constant shape and a constant volume. ○ A solid substance like a piece of wood will keep it shape and size under normal circumstances. ○ Solids can be flexible. A rubber band is a solid, but it can stretch. Although you can temporarily change its shape, it will return to is original shape when not being acted upon.  A liquid has a variable shape, but a constant volume. ○ A liquid will take on the shape of its container, however the volume will stay the same. If you pour 100mL of water into a flat pan, the water will take on the shape of the flat pan but will still remain 100mL. ○ If you pour 100mL of water into a tall glass, the water will take on the shape of the tall glass but will still remain 100mL.  A gas has a variable shape and variable volume. ○ Gases take on the shape of their container like liquids, but have the ability to expand.  Plasma does not follow the rules above. Plasma is the high energy state of matter that is found in lightning, fire, etc.
  • 4. More about changes of state…change from one state of matter to another.  Liquid to Solid / Solid to Liquid  If something changes from a liquid to a solid it is called freezing. ○ Substances do not have to be “cold” to freeze. Most metals will change from liquid metal to solid metal at room temperature.  If something changes from a solid to a liquid it is called melting. ○ Substances do not have to be “hot” to melt. Ice will melt at room temperature.  Liquid to Gas / Gas to Liquid  If something changes from a liquid to a gas it is called vaporization. ○ After a rain, the liquid water (H2O) on the ground eventually disappears. The water changes from a liquid to H2O gas in the air.  If something changes from a gas to a liquid to a gas it is called condensation. ○ Clouds are a result of H2O changing from a gas to a liquid.
  • 5. Chemical Changes A chemical change is when a substance changes into a new substance.  Change into a new substance.  When a chemical change occurs, a new substance forms that has completely different properties than the original substance. ○ Paper is a white solid. When paper is burned, it is turned into ash which is a black, flaky substance. Ash has completely different properties than paper. ○ When sodium, a slivery colored soft metal is combined with chlorine, a green poisonous gas, it forms table salt!  When a chemical change occurs it is very difficult if not impossible to return the substance to its original form. ○ Once paper has burned and turned into ash, it is impossible to turn it back into paper!
  • 6. More about chemical changes…new substance.  The there are four indicators that a chemical change may have occurred and something has changed into a new substance. (Be careful there are exceptions to each rule!)  Change in color. ○ When white paper turns into black ash, a color change and a chemical change has occurred.  Gasses are given off. ○ When a piece of paper is burned, smoke and other gasses such as carbon monoxide are produced.  Something gets hot and / or a light is produced. ○ When things get hot, as when paper is burned, a chemical change may have occurred. ○ When the chemicals in a glow stick are combined, the glow stick produces light.  Something gets cold. ○ When the chemicals are mixed within a cold pack, the cold pack gets cold.
  • 7. Is this a Physical or Chemical change? Bread Toasting….. This is a Chemical Change! Butter melting on your toast….. This is a Physical Change!
  • 8. Is this a Physical or Chemical change? Getting a haircut….. This is a Physical Change! Ice Cubes Melting….. This is a Physical Change too!
  • 9. Is this a Physical or Chemical change? Fireworks Exploding….. This is a Chemical Change! A bike rusting….. This is a Chemical Change too!

×