Heats Of Reactions

HEATS OF REACTIONS ·MIREIAJIMÉNEZROSÉS·DAVIDVÁZQUEZCALDERERO·

MENU •INTRODUCTION •EXPERIMENT

1 •EXPERIMENT 2 •QUESTIONS

& SAFETY

INTRODUCTION SOME 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 1 MATERIALS TEST TUBE

TEST TUBE RACK

HYDROCHLORIC ACID

POWER ZINC

GRADUATE CYLINDER THERMOMETER

SPATULA

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 TEST TUBE

TEST TUBE RACK

CITRIC ACID

SODIUM HYDROGENCARBONA GRADUATE CYLINDER TE THERMOMETER

SPATULA

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.

QUESTIONS INFORMATION EXPERIMEN T

1

2

TEMPERATUR E OF LIQUID

FINAL TEMP. OF MIXTURE

21ºC

44.5ºC

21ºC

12ºC

TEMPERATUR E CHANGE

+23.5ºC -10ºC

NOW DO IT: 1. WHICH REACTION IS EXOTHERMIC AND WHICH The reaction 1 is EXOTHERMIC, because the ENDOTHERMIC? temperature increase 23.5ºC. The reaction 2 is ENDOTHERMIC, because the temperature decrease 10ºC. zinc  zinc chloride FOR 2. Hydrochloric WRITE WORDacid AND+SYMBOL EQUATIONS 2 HCl+ Zn  EXPERIMENT 1. ZnCl2 + H2 Sodium hydrogencarbonate + citric acid  sodium citrate + + carbon 3. water WRITE WORDdioxide EQUATION FOR EXPERIMENT 2.

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