Changes in Matter Physical VS Chemical

ChangesI8A: The student knows that

changes in matter affect everyday life. The student is expected to

distinguish between physical and chemical changes in matter such as

oxidation, digestion, changes in states, and stages in the rock cycle.

Ice cream melting is a physical change.

In a physical change, the form of a substance or some of the substances properties may change, but its chemical composition – the way its atoms are put together – remains unchanged. The matter involved in a physical change keeps its identity!

Physical Changes

www.julieleung.com/ archives/2004_07.html

Chemical ChangesIn a chemical change,

the elements of one compound recombine to form one or more new chemical compounds with different properties.

2 Na + 2 H2O        > 2 NaOH + H2

www.pc.chemie.uni-siegen.de/.../ v44-1-1.html

To view this reaction go to: http://www.pc.chemie.uni-siegen.de/pci/versuche/pics/anim/natrium.mpg

Signs of a Chemical Change:

1. Heat or light is produced.

2. Gas is produced.3. Precipitate forms.

http://www.sfrisch.com/chem_cov.

Example of precipitate:

Verbs to help you determine a Physical VS Chemical Change:

Physical:1. Evaporate2. Melt3. Heat4. Condensation5. Cool6. Compress7. Subduction8. Shattering9. Dissolving

Chemical:1. Burning2. Forming or Form3. Becoming4. Turning to5. Rusting6. Baking7. Weathering 8. Combining9. Damaging

Have a student:1. Rip a sheet of paper

2. Grind or crush a piece of chalk

3. Place powdered chalk into a test tube and add 5% acetic acid (vinegar)

4. Dissolve salt in water

5. Light a candle

1. Identify the following as physical or chemical changes:

1. Liquid water evaporates

2. Iron rusting3. Salt dissolves in

water4. Milk turning sour5. Baking a cake

6. Burning wood7. Fireworks8. A gas condenses

to become a liquid9. Ripping a sheet of

paper10. Slicing a cake

The Rock Cycle

One of nature’s slowest processes – the rock cycle – is a repeating series of physical and chemical changes in which one type of rock changes to another type.

http://science.cc.uwf.edu/sh/curr/rockcyc/rockcyc.htm

 

2. In the rock cycle, which of these is a chemical change involved with the formation of igneous rocks?

 F Compression of sedimentsG Heat loss from lavaH Subduction of platesJ Formation of minerals 

Question is from TEA Released TAKS Test

3. Which of these changes in rocks is a physical change?

 A Acid rain damaging marbleB Iron in rock combining with oxygen to form hematiteC Carbonic acid weathering limestoneD An ice wedge shattering a slab of shale

Question is from TEA Released TAKS Test

4. Which of the following processes is an example of a physical change associated with an oak tree?

 A Decomposition of bark by bracket fungiB Starches and sugars being broken down

during energy productionC Water and carbon dioxide being converted

to glucoseD Evaporation of water from the surfaces of

Leaves