Chemical and Physical ChangePractical InvestigationsYear 8 Science 2021

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Name: ____________________________Chemical and Physical Change

Aim: To observe and identify chemical and physical changes

Materials: Aspro clear tablets 100 mL Measuring cylinder Vinegar Magnesium ribbon Sparkler Matches Soda can Heat/cold pack Glow stick 250 mL Beakers x2 Thermometer

Ice Spatula 0.1 M Barium chloride 1.0 M Sulphuric acid 0.1 M Copper sulphate 0.5M Potassium iodide Sodium bicarbonate 1.0 M Hydrochloric acid Test tubes x4 Test tube rack

Method:1. Measure 100 mL of water in a measuring cylinder. Pour into beaker. Place tablet into the water and record your observations. 2. Add a small amount of hydrochloric acid to a test tube (approx. 2cm from the bottom). Place a thermometer into the test tube. Add a small piece of magnesium ribbon and record your observations. 3. Using a match, light a sparkler and record your observations 4. Squash a soda can by stepping on it and record your observations5. Crush a hot/pack cold pack and shake the packet (follow the instructions on the packet) and record your observations6. Bend the glowstick until you hear a crack. Shake the glowstick and record your observations7. Add a small amount of barium chloride to a test tube (approx. 2cm from the bottom). Add approximately the same amount of sulphuric acid and record your observations.8. Add a small amount of copper sulphate to a test tube (approx. 2cm from the bottom). Add approximately the same amount of potassium iodide and record your observations.

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9. Add a small amount of vinegar to a test tube (approx. 2cm from the bottom). Using a spatula, add two scoops of sodium bicarbonate and record your observations.10. Place a piece of ice on a tile. Leave for 10 minutes and record your observations.11. Place 100 mL of water into a beaker using a measuring cylinder. Add 2 drops of food dye and record your observations

Results/Discussion:Q1. Fill in the table below with your observations and determine if a chemical or physical change was observed.

Reaction Observations Chemical/Physical Change

1. Sparkler(Teacher Demo)

2. Add hydrochloric acid to a small piece of magnesium3. Dissolving tablet in water

4. Soda can

5. Heat/Cold Pack

6. Glow stick

7. Add barium chloride to sulphuric acid

8. Add copper sulphate to potassium iodide9. Add sodium bicarbonate to vinegar

10. Ice

11. Dye in water

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Q2. Explain the terms chemical and physical change: ___________________________________________________________________________________________________________Q3. What are the signs of a chemical change? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Rate of reactions Part A – Investigating enzymesAim: To investigate the effect of enzymes on the rate of reaction

Hypothesis: ______________________________________________________________________________________________________________________________________________________________________________________________________________________Materials:

2 packets of dried yeast 250 mL conical flask x2 10 mL hydrogen peroxide

(3%) 2 balloons

10 mL measuring cylinder Stopwatch Ruler Distilled water

Method:1. Add the yeast into the conical flask2. Add 10mL of the hydrogen peroxide into conical flask3. Attach a balloon to the conical flask, sealing the top4. Start the timer. At 2 minutes, use a ruler to measure the size of the

balloon5. Repeat steps 1-4 using 10mL of distilled water instead of hydrogen

peroxide 6. Record your observations in the table belowResults:

Size of balloon (cm)Yeast and hydrogen peroxide

Yeast and water

Discussion:1. State the following variables in this experiment:

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a) Independent variable: ________________________________________________

b) Dependent variable: _________________________________________________

c) Controlled variables: ________________________________________________

2. Explain if this reaction in an example of a chemical or physical change_____________________________________________________________________

3. Use the particle model to explain how enzymes impact on the rate of reaction

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Part B – Investigating surface area

Aim: To investigate the effect of surface area on the rate of reaction

Hypothesis: ______________________________________________________________________________________________________________________________________________________________________________________________________________________Materials:

Icing sugar, white sugar, sugar cube

Stopwatch Stirring rod

Electronic balance Spatula Measuring cylinder 250mL beakers x3

Method:1. Using a measuring cylinder, fill 3 medium sized beakers with 100ml of water2. Using an electronic balance, weigh a sugar cube in a small beaker and record its weight (be sure to zero the beaker, we only want the weight of the sugar cube)3. Using a spatula, weigh the same amount of icing sugar into one small beaker and white sugar in the other. Record these exact weights into your table4. Start the stopwatch at the same time you add the sugar into the large beaker of water5. Stir slowly at a constant rate (do not crush the cube)6. Record the time it took for all of the sugar cube to dissolve 7. Repeat steps 4-6 for the other two sugars

Results:5

Icing Sugar White Sugar Sugar CubeWeight (g)

Time (sec)

Discussion:1. State the following variables in this experiment:

a) Independent variable: ________________________________________________

b) Dependent variable: _________________________________________________

c) Controlled variables: ________________________________________________

2. Explain if this reaction in an example of a chemical or physical change_____________________________________________________________________

3. Use the particle model to explain how surface area impacts on the rate of reaction

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Part C – Investigating temperature

In part B, you recorded the time taken to dissolve white sugar at room temperature, in this section, you will use the same amount of sugar except this time put it into hot water.

Aim: To investigate the effect of temperature on the rate of reaction

Hypothesis: ______________________________________________________________________________________________________________________________________________________________________________________________________________________Materials:

White sugar Stopwatch Stirring rod Electronic balance

Spatula Measuring cylinder 250mL beaker Kettle/hot water

Method:1. Using an electronic balance, weigh out the same amount of white sugar from Part B2. Using a measuring cylinder, fill a medium sized beaker with 100ml of hot water from the kettle/urn

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3. Start the stopwatch at the same time you add the sugar into the large beaker of water4. Stir slowly at a constant rate as you did in Part B6. Record the time it took for the sugar to dissolve

Results:White sugar at

room temperature (Part B)

White Sugar in hot water

Weight (g)

Time (sec)

Discussion:1. State the following variables in this experiment:

a) Independent variable: ________________________________________________

b) Dependent variable: _________________________________________________

c) Controlled variables: ________________________________________________

2. Explain if this reaction in an example of a chemical or physical change_____________________________________________________________________

3. Use the particle model to explain how temperature impacts the rate of reaction

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Types of chemical reactions - Rusting

Aim: To observe the conditions under which rusting occurs

Hypothesis: ______________________________________________________________________________________________________________________________________________________________________________________________________________________Materials:

3 large test tubes7

Test tube rack 3 pieces of steel wool or iron nails Distilled water Sodium chloride solution

Method: 1. Place one piece of steel wool (or iron nail) in each of the three test

tubes.2. Do not add anything to the first test tube3. To the second test tube, add distilled water so that the wool (or nail)

is half submerged4. To the third test tube, add salt water so that the wool is half

submerged5. Observe the reaction after 5 days and record your results in the

tableResults:

No water Water Water + Salt

Discussion:1. State what evidence there is that a chemical reaction has taken

place_____________________________________________________________________

2. Write the word and formula equations for rusting__________________________________________________________________________________________________________________________________________

3. List what is necessary for rusting to occur_____________________________________________________________________

4. Explain why iron structures such as car bodies rust raster in coastal areas rather than inland __________________________________________________________________________________________________________________________________________Additional Practical Activities/Demos

Activity 1 – Dissolving sugar and temperature

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Activity 3 – Sublimation Demo

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Activity 2 – Rate of diffusion

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