8/18/2019 Exercise 14-Physical and Chemical Changes

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Exercise 13

Physical & Chemical Changes

Chemistry is the study of matter and the changes it undergoes. These changes can be broken down into two

classes—physical changes and chemical changes. In a physical change, one or more physical properties of a

substance are altered. Examples of such physical properties include size, shape, color, and physical phase. rinding,melting, dissol!ing, and e!aporating all are physical changes. "o new substance or substances are formed as a result

of a physical change. # chemical change results in the formation of one or more $new$ substances. These new

substances differ in chemical properties and composition from the original substance. The rusting of iron and the

 burning of paper are two examples of chemical change. This experiment will help you to understand the difference

 between physical and chemical change and to recognize each type of change when it occurs.

PURPOSE

%ecognize and distinguish between chemical and physical changes.

EQUIPMENT

lab balance micro spatula lab burner dropper pipette

& test tubes '()xl&*+mm mortar and pestle test tube rack magnet

test tube holder insulating pad watch glass safety goggles

glass s-uare lab apron or coat

MATERIALS

Copper sulfate penta+hydrate iron filings 'e

/agnesium ribbon '/g sodium chloride '"aCI paper '& cm x (* cm

0ydrochloric acid '1 / 0Cl birthday candle sil!er nitrate '*.( / #g"23 matches

4ulfur '4 powdered salt

SAET!

5hen heating a substance in a test tube, be sure the open end of the tube points away from yourself and others.

0andle all acids with extra caution. #lways wear safety goggles when handling acids. %eport all acid spills to your

teacher, and flush with cold water and a dilute solution of sodium bicarbonate '"a0C23.i!e heated glass ample

time to cool before handling it. lass retains heat. Tie back long hair and secure loose clothing before working withan open flame. 5ear safety goggles and a lab apron or coat at all times when working in the lab.

PROCE"URE

 "ote and record all obser!ations in your data table.

(. 6lace a small amount of wax from a birthday candle into a test tube. 0eats gently o!er a burner flame until thewax melts completely7 then allow the sample to cool. "ext, light the candle, secure it to a glass s-uare, and allow it

to burn until it extinguishes itself. 6roceed with the rest of the experiment while the candle burns.

8. Tear a piece of paper 'about & cm x (* cm into small pieces. 4et a watch glass on an insulating s-uare and placethe pieces of paper on the glass. Ignite the paper with a match and allow to burn.

8/18/2019 Exercise 14-Physical and Chemical Changes

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3. #dd a micro spatula of "aCI 'sodium chloride to a small -uantity of water 'about & m9 in a test tube. 4hake the

contents of the tube. "ext, use a dropper to add (* drops of *.( / #g"23 'sil!er nitrate to the "aCl+water mixture.

:. 2btain a piece of magnesium ribbon about & cm long. Tear the ribbon into (+cm pieces. 6lace two of the piecesinto a test tube and add a few drops of 1 / 0Cl 'hydrochloric acid.

C#;TI2"< ;se extreme care in handling this acid. It will cause se!ere burns if allowed to come in contact with the

skin. Touch the bottom of the test tube with your fingertip.www.siraze.net=chemistry

&. ;se a mortar and pestle to grind se!eral crystals of Cu42: & 082 into a uniform powder. 6lace one

microspatula of the powder into a test tube. 0eat gently o!er a burner flame for & minutes. #llow the sample to cooland then add a few drops of water.

1. ;sing a lab balance, measure out the following samples< *.&* g of iron filings and *.&* g of powdered sulfur. Test

each sample with a magnet. /ix the two samples thoroughly in a test tube. %un the magnet along the bottom andsides of the test tube.

O#SER$ATION AN" "ATA

%ecord all -ualitati!e obser!ations for each step of the procedure.

CONCLUSION AN" QUESTIONS

(. Indicate whether the following changes are physical or chemical. 4upport your conclusion.

a /elting candle wax

 b >urning a candle

c Tearing paper 

d >urning paper 

e ?issol!ing "aCl

f /ixing "aCl with #g"23

g Tearing /g ribbon

h #dding 0Cl to /g

i rinding Cu42: & 082

 @ 0eating Cu42: & 082

k /ixing e and 4

l 0eating a mixture of e and 4