커피컵 열량 측정

간단한 열량계로 중화 엔탈피 측정하기

Thermochemistry Intermediate (High School) 40 분 ~$8.00

목표

폴리스타이렌 컵 열량계를 사용하여 HCl과 NaOH의 중화 엔탈피를 결정한다.

배경

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.

안전 경고

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

필수 개인 보호 장비

goggles gloves lab_coat

재료

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

장비

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

실험 절차

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 분 HCl is corrosive
2

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

2 분 NaOH is corrosive
3

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

1 분 Exothermic reaction
4

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

5 분
5

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

5 분
6

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

8 분

예상 결과

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.

정리

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

세부 정보

카테고리
Thermochemistry
난이도
Intermediate (High School)
소요 시간
40 분
예상 비용
$8.00
단계
6
재료
3

더 많은 실험

아세트산나트륨의 발열 결정화 30 min 마그네슘의 연소열 50 min 금속의 비열 용량 40 min 헤스의 법칙 검증 60 min 얼음의 융해 엔탈피 25 min 용해는 항상 발열이 아니다 25 min 냉찜질 팩의 화학 원리 20 min 폭탄 열량계 시뮬레이션 45 min 흡열 반응 실험 20 min

Frequently Asked Questions

What is the objective of 커피컵 열량 측정?
폴리스타이렌 컵 열량계를 사용하여 HCl과 NaOH의 중화 엔탈피를 결정한다.
How difficult is 커피컵 열량 측정?
This experiment is rated as Intermediate (High School). It takes approximately 40 minutes to complete.
What safety precautions are needed for 커피컵 열량 측정?
Key safety precautions include: HCl and NaOH are corrosive; Wear safety goggles; The mixture will get hot.
What materials are needed for 커피컵 열량 측정?
The main materials required are: Hydrochloric acid (HCl), Sodium hydroxide (NaOH), Distilled water.
What results should I expect from 커피컵 열량 측정?
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.