Калориметрия в кофейной чашке

Измерение теплоты нейтрализации с помощью простого калориметра

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

Цель

Определить теплоту нейтрализации HCl и NaOH с помощью калориметра из пенополистирольного стакана.

Предпосылки

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.

Предупреждения по безопасности

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

Требуемые СИЗ

goggles gloves lab_coat

Материалы

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

Оборудование

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

Процедура

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 мин HCl is corrosive
2

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

2 мин NaOH is corrosive
3

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

1 мин Exothermic reaction
4

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

5 мин
5

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

5 мин
6

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

8 мин

Ожидаемые результаты

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.

Уборка

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

Детали

Категория
Thermochemistry
Сложность
Intermediate (High School)
Продолжительность
40 мин
Прим. стоимость
$8,00
Шаги
6
Материалы
3

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Frequently Asked Questions

What is the objective of Калориметрия в кофейной чашке?
Определить теплоту нейтрализации HCl и NaOH с помощью калориметра из пенополистирольного стакана.
How difficult is Калориметрия в кофейной чашке?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for Калориметрия в кофейной чашке?
Key safety precautions include: HCl and NaOH are corrosive; Wear safety goggles; The mixture will get hot.
What materials are needed for Калориметрия в кофейной чашке?
The main materials required are: Hydrochloric acid (HCl), Sodium hydroxide (NaOH), Distilled water.
What results should I expect from Калориметрия в кофейной чашке?
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.