Calorimetría en Vaso de Café

Medición de la entalpía de neutralización usando un calorímetro simple

Thermochemistry Intermediate (High School) 40 min ~$8,00

Objetivo

Determinar la entalpía de neutralización de HCl y NaOH usando un calorímetro de vaso de poliestireno.

Antecedentes

A polystyrene cup makes an inexpensive but effective calorimeter because it has low thermal conductivity. By mixing known volumes of acid and base and measuring the temperature change, the enthalpy of neutralization can be calculated. The accepted value for strong acid-strong base neutralization is -57.1 kJ/mol.

Advertencias de seguridad

  • HCl and NaOH are corrosive
  • Wear safety goggles
  • The mixture will get hot

EPP requerido

goggles gloves lab_coat

Materiales

  • Hydrochloric acid (HCl) (50 mL)
    1M
  • Sodium hydroxide (NaOH) (50 mL)
    1M
  • Distilled water (100 mL)
    For calibration

Equipamiento

Two polystyrene (Styrofoam) cups (nested) Cardboard lid with hole Thermometer (0.1°C resolution) Graduated cylinder (50 mL) Stopwatch

Procedimiento

1

Measure 50 mL of 1M HCl and pour into the nested polystyrene cups. Record the initial temperature every 30 seconds for 3 minutes.

5 min HCl is corrosive
2

Measure 50 mL of 1M NaOH in a separate container. Record its temperature.

2 min NaOH is corrosive
3

Quickly pour the NaOH into the HCl, stir gently, and replace the lid with thermometer.

1 min Exothermic reaction
4

Record the temperature every 30 seconds for 5 minutes. Note the maximum temperature.

5 min
5

Plot temperature vs time. Extrapolate the cooling curve back to the mixing time to find the corrected maximum temperature.

5 min
6

Calculate ΔT, then q = mcΔT (assume c = 4.18 J/g°C, mass = 100 g). Calculate ΔH per mole of water formed.

8 min

Resultados esperados

Temperature should rise by approximately 6-7°C. Calculated ΔH should be approximately -50 to -57 kJ/mol (accepted: -57.1 kJ/mol). Losses to the calorimeter walls typically give lower values.

Limpieza

The neutralized solution is safe to pour down the drain. Rinse and dry the calorimeter cups for reuse.

Detalles

Categoría
Thermochemistry
Dificultad
Intermediate (High School)
Duración
40 min
Costo estimado
$8,00
Pasos
6
Materiales
3

Más experimentos

Calor de Combustión del Magnesio 50 min Capacidad Calorífica Específica de Metales 40 min Cristalización Exotérmica de Acetato de Sodio 30 min Demostración de Reacción Endotérmica 20 min Entalpía de Fusión del Hielo 25 min La Disolución No Siempre Es Exotérmica 25 min Química de las Bolsas de Frío 20 min Simulación de Calorimetría en Bomba 45 min Verificación de la Ley de Hess 60 min

Frequently Asked Questions

What is the objective of Calorimetría en Vaso de Café?
Determinar la entalpía de neutralización de HCl y NaOH usando un calorímetro de vaso de poliestireno.
How difficult is Calorimetría en Vaso de Café?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for Calorimetría en Vaso de Café?
Key safety precautions include: HCl and NaOH are corrosive; Wear safety goggles; The mixture will get hot.
What materials are needed for Calorimetría en Vaso de Café?
The main materials required are: Hydrochloric acid (HCl), Sodium hydroxide (NaOH), Distilled water.
What results should I expect from Calorimetría en Vaso de Café?
Temperature should rise by approximately 6-7°C. Calculated ΔH should be approximately -50 to -57 kJ/mol (accepted: -57.1 kJ/mol). Losses to the calorimeter walls typically give lower values.