lab demo activities

LAB DEMO ACTIVITIES

1. Blue Bottle2. Foam Column3. Solid Reaction4. Flame Tests5. Burning Magnesium6. Carbon Pillar

Skills Focus:

Making Observations

Qualitative vs. Quantitative

Aim: To find out the different signs of a chemical change.

Qualitative observations use your senses to observe the results. (sight, smell, touch, taste and hear.)

Quantitative observations are made with instruments such as rulers, balances, graduated cylinders, beakers, and thermometers. These results are measurable.

CHEMICAL CHANGES

Lab Demos

1. Blue Bottle•Measure 5g Dextrose•Measure 5g NaOH pellets•Add to 250ml water•Place ¼ drop 1% methylene blue•Conical flask•Stopper•Shake the flask until NaOH is dissolved•Wait

2. Foam Column

•Potassium Permanganate (flat spoonful)•Squirt of detergent - enough to cover the KMnO4•30-50ml of hydrogen peroxide (slowly add)

3 4. Flame Tests

Different solutions of metal salts

• Observe what happens when the solution is ignited.

6. Carbon Pillar

• 40ml white sugar• H2SO4• Small beaker (80ml)• Enough of the H2SO4 to cover the

sugar

5.

Evidence of chemical reactions

Lab Demo Diagram Observations

1

2

3

Part A - Observations

Evidence of chemical reactions

Name Diagram Observations

4

5

6

Part B - Indications of chemical reactionMake a list of all the observations from above that indicates a chemical reaction has taken place.

FLAME TESTSRelease of

Light Energy

Li

FLAME COLORS

When ignited, metal particles get excited

and when it goes back to its ground state

release energy in the form of light.

Metal Salts Flame Color

Calcium chloride Yellowish red

Strontium chloride Scarlet red

Sodium chloride Bright yellow-orange

Potassium chloride Lilac

Barium chloride Pale green

Lithium chloride Carmine red (less intense red)

Metal salts introduced into a flame give off light characteristic of the metal.

1. Blue Bottle•Measure 5g Dextrose•Measure 5g NaOH pellets•Add to 250ml water•Place ¼ drop 1% methylene blue•Conical flask•Stopper•Shake the flask until NaOH is dissolved•Wait

2. Foam Column

•Potassium Permanganate (flat spoonful)•Squirt of detergent - enough to cover the KMnO4•30-50ml of hydrogen peroxide (slowly add)

3.Burning Magnesium

•2cm of Mg•Hold in tongs•Ignite

• color change• reversible reactions

• Gas and heat

• light and change in form; new substance

5. Solid Reaction• 1 test tube containing Potassium

Iodide• 1 test tube containing Lead Nitrate• Pour the KI into a conical flask• Carefully lower the test tube of

PbNO3 into the flask• Place on stopper• Place on balance and zero• Tilt flask to spill the PbNO3

• change in color• change in state

7. Carbon Pillar

• 40ml white sugar• H2SO4• Small beaker (80ml)• Enough of the H2SO4 to cover the sugar

•Gas formation •change in color• change in state• change in temp

SUMMARY

From the 6 demos, the following are signs of a chemical reaction: • • • •

These signs are seen in the …. (cite examples from the demos)

AssessmentItem Assessment Criteria Point

sStudent

Evaluation

Instructor

Evaluation

Performance

Accurately recorded observations for all (8) activities 4

Labeled diagrams clearly illustrates set-up for the labs 4

Summary conclusion accurately describes signs of a chemical reaction

2

TOTAL (out of) 10

SIGNS OF CHEMICAL RXNS Color change - new substances might reflect different colors of light. Heat change - the container may get hotter or colder. Gas produced - bubbles or smoke may be observed. Precipitate formed - an insoluble solid might form in a liquid.

Chemical RXNs

Reactants Products

Parts of a rxn:   Reactants

•Substances that interact with each other; left side of the arrow in a chemical equation.   Products •New substances formed during a reaction; right side of the arrow in a chemical equation.

A + B CC A + B

A + BX AX + BAX + BY AY + BX

FORM

SEPARATE

SWITCH 1

SWITCH 2

Mg + O2

Chemical Reaction

+

Mg + O2

Chemical Reaction

+

Mg O

Bright Light

•WORD EQUATION•CHEMICAL EQUATION

REACTION OF COPPER POWDER

REACTION OF COPPER POWDER

Copper Oxide

(2CuO)Pesticide

Fungicide

2Cu + O2 (2CuO)