Chemical ReactionChemical Reaction

CLASS / SEMESTER : VII / 2

JUNIOR HIGH SCHOOL

What is a chemical reaction?What is a chemical reaction?

A chemical reaction can be A chemical reaction can be identified based on the identified based on the change happening in the change happening in the reactionreaction

Chemical reaction produce 4 Chemical reaction produce 4 types of reactiontypes of reaction

They are…………..They are…………..

1.1.PrecipitationPrecipitation

2.2.Colour changeColour change

3.3.Temperature changeTemperature change

4.4.GasGas

1.1. PrecipitationPrecipitationA bottom of pan : Carbonate A bottom of pan : Carbonate compound ( heated water )compound ( heated water )

Calcium Carbonate (CaCO3) : lime Calcium Carbonate (CaCO3) : lime water + CO2 (breath)water + CO2 (breath)

Industry : in the process of water Industry : in the process of water purificationpurification

2. Color Changes2. Color Changes

Apple is cut or peeled : brownApple is cut or peeled : brown

Iron : blackIron : black

Silver : blackSilver : black

Copper : greenCopper : green

3. Gas3. Gas

Carbide + water : Acetylene ( gas )Acetylene : - welding process to join metals- to ripen some fruits

Bake a cake: baking soda Bake a cake: baking soda + dough + heat : dough + dough + heat : dough expandexpand

3. Gas3. Gas

A firecracker that explodesA firecracker that explodes

carbide + water : rising carbide + water : rising temperature on the wall of temperature on the wall of the glassthe glass

4. Temperature Change4. Temperature Change

evaluationevaluationWRITTEN TESTWRITTEN TEST

1. Chemical reaction that results in a change of 1. Chemical reaction that results in a change of colour happens when….colour happens when….

a.a. iron becomes red after it is paintediron becomes red after it is painted

b.b. apple becomes brown when it is peeledapple becomes brown when it is peeled

c.c. orange is squeezed to get the juice with orange is squeezed to get the juice with yellow colouryellow colour

d.d. the colour of a rainbow in the skythe colour of a rainbow in the sky

ESSAYESSAY

After being washed several times, After being washed several times, bright colour on clothes will fade bright colour on clothes will fade out. Do physical or chemical change out. Do physical or chemical change or both ?or both ?

Procedural checklist test :Procedural checklist test :

Identify the following reaction. Fill in the blanks with : Identify the following reaction. Fill in the blanks with : precipitation, gas production, change of colour and precipitation, gas production, change of colour and change of temperature.change of temperature.……………………………………………………..1. A ripe banana turns yellow..1. A ripe banana turns yellow……………………………………………………..2. A cake dough will grow if ..2. A cake dough will grow if heatedheated……………………………………………………..3. Lime water will be discolour if ..3. Lime water will be discolour if added with CO2added with CO2……………………………………………………..4. Car engine will be hot after ..4. Car engine will be hot after the gasoline is burnedthe gasoline is burned…………………………………………………….5. A peeled apple will turn down.5. A peeled apple will turn down……………………………………………………..6. A glass of milk crumple if add ..6. A glass of milk crumple if add with vinegarwith vinegar