HEATS OF HEATS OF REACTIONSREACTIONS

·MIREIAJIMÉNEZROSÉS·DAVIDVÁZQUEZCALDERERO·

•INTRODUCTION & SAFETY•EXPERIMENT 1 •EXPERIMENT 2•QUESTIONS

MENU

INTRODUCTIONSOME REACTION GIVE OUT HEAT AND OTHER TAKE IN HEAT. THEIR NAMES ARE: • IN EXOTHERMIC REACTIONS, THE TEMPERATURE GOES UP BECAUSE IT TRANSFERS HEAT FROM THE SURROUNDING. • IN ENDOTHERMIC REACTIONS, THE TEMPERATURE GOES DOWN BECAUSE IT ABSORBS HEAT FROM THE SORROUNDING.

• WEAR EYE PROTECTION FOR DO THE NEXT EXPERIMENTS.• ZINC POWDER IS FLAMMABLE.•CLORHIDRIC ACIS IS AN ACID CORROSIVE.

SAFETY

EXPERIMENT 1MATERIALS

THERMOMETER SPATU

LA

GRADUATED

CYLINDER

TEST TUBE

TEST TUBE RACK

POWER ZINC

CLORHIDRIC ACID

PROCEDURE

1. PUT ABOUT 5 CM3 OF CLORHIDRIC ACID.

2. RECORD THE TEMPERATURE OF THE CLORHIDRIC ACID.

3. ADD A SPATULA OF POWDERED ZINC.

4. WATCH WHAT HAPPENS AND TAKE THE TEMPERATURE

OF THE SOLUTION.

EXPERIMENT 2 MATERIAL

S

SODIUM HYDROGENCARBON

ATE

CITRIC ACID

TEST TUBE

TEST TUBE RACK

THERMOMETER

SPATULA

GRADUATED

CYLINDER

PROCEDURE

1. IN A DRY TEST TUBE MIX ONE SPATULA OF CITRIC ACID AND ONE SPATULA OF SODIUM HYDROGENCARBONATE.

2. PUT 2 CM3 OF WATER IN ANOTHER TEST TUBE.

3. RECORD THE TEMPERATURE OF THE WATER.

4. ADD THE MIXTURE TO THE WATER.

5. WATCH WHAT HAPPENS AND TAKE THE TEMPERATURE OF THE SOLUTION.

QUESTIONSINFORMATION

EXPERIMENT

TEMPERATURE OF LIQUID

FINAL TEMP. OF MIXTURE

TEMPERATURE CHANGE

1 21ºC 44.5ºC +23.5ºC

2 21ºC 12ºC -10ºC

NOW DO IT:1. WHICH REACTION IS EXOTHERMIC AND WHICH ENDOTHERMIC?

2. WRITE WORD AND SYMBOL EQUATIONS FOR EXPERIMENT 1.

3. WRITE WORD EQUATION FOR EXPERIMENT 2.

The reaction 1 is EXOTHERMIC, because the temperature increase 23.5ºC. The reaction 2 is ENDOTHERMIC, because the temperature decrease 10ºC.Clorhidric acid + zinc zinc chloride2 HCl+ Zn ZnCl2 + 2 H

Sodium hydrogencarbonate + citric acid sodium citrate + water + carbon dioxide

END