HEATS OF HEATS OF REACTIONSREACTIONS

·MIREIAJIMÉNEZROSÉS·DAVIDVÁZQUEZCALDERERO·

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

MENU

INTRODUCTIONSOME REACTIONS GIVE OUT HEAT AND OTHER TAKE IN HEAT.

• IN EXOTHERMIC REACTIONS, THE TEMPERATURE GOES UP BECAUSE IT TRANSFERS HEAT FROM THE SURROUNDINGS.

• IN ENDOTHERMIC REACTIONS, THE TEMPERATURE GOES DOWN BECAUSE IT ABSORBS HEAT FROM THE SORROUNDINGS.• WEAR EYE PROTECTION TO CARRY OUT THE NEXT EXPERIMENTS.• ZINC POWDER IS FLAMMABLE.•HYDROCHLORIC ACID IS CORROSIVE.

SAFETY

EXPERIMENT 1MATERIALS

THERMOMETERSPATULA

GRADUATE CYLINDER

TEST TUBE

TEST TUBE RACK

POWER ZINC

HYDROCHLORIC ACID

PROCEDURE

1. PUT ABOUT 5 CM3 OF HYDROCHLORIC ACID.

2. RECORD THE TEMPERATURE OF THE ACID.

3. ADD A SPATULA OF POWDERED ZINC.

4. WATCH WHAT HAPPENS AND RECORD THE TEMPERATURE OF THE SOLUTION.

EXPERIMENT 2 MATERIAL

S

SODIUM HYDROGENCARBONA

TE

CITRIC ACID

TEST TUBE

TEST TUBE RACK

THERMOMETER SPATULA

GRADUATECYLINDER

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.Hydrochloric acid + zinc zinc chloride2 HCl+ Zn ZnCl2 + H2

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

END