Intermediate Topic 345 of 1102 Thermodynamics & Energetics
Coffee-Cup Calorimeter
A constant-pressure calorimeter for measuring enthalpy changes in solution.
Practise Thermodynamics & Energetics All Thermodynamics & Energetics topics
In-depth explanation of Coffee-Cup Calorimeter
A coffee-cup calorimeter is a simple device made from two nested polystyrene cups, insulated and open to the atmosphere, which makes it a constant-pressure apparatus. Because the reaction takes place at atmospheric pressure, the heat measured in the cup equals the enthalpy change of the reaction, q_p equal to delta H. It is most suited to reactions in aqueous solution, such as neutralizations and dissolutions, where the solution itself acts as the calorimetric medium. Heat losses to the environment are small but not zero, so experiments often correct for them with a calorimeter constant. The method is inexpensive and widely used in teaching laboratories.
Going deeper: Coffee-Cup Calorimeter
Key ideas: Because it runs at atmospheric pressure, the measured heat is the enthalpy change. Assume the solution has the density and specific heat of water unless told otherwise, and assume the cup absorbs negligible heat unless a calorimeter constant is given. The enthalpy per mole is minus q divided by moles of limiting reagent.
Common mistakes and connections: Mistakes include forgetting that mixing two volumes gives a total mass of both solutions and using the volume of only one. Heat loss to the air makes values slightly low in magnitude. This device is the standard tool behind enthalpy of neutralization and of solution measurements.
Visualization of Coffee-Cup Calorimeter
The open, insulated cup keeps constant pressure, so heat measured in the solution equals the enthalpy change; the liquid's particles show the solution warming. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Mixing 50 mL of 1.0 M hydrochloric acid with 50 mL of 1.0 M sodium hydroxide in a cup gives a temperature rise from which the molar enthalpy of neutralization is calculated.
Frequently asked questions about Coffee-Cup Calorimeter
What is Coffee-Cup Calorimeter?
A constant-pressure calorimeter for measuring enthalpy changes in solution.
Is Coffee-Cup Calorimeter a beginner, intermediate or advanced topic?
Coffee-Cup Calorimeter is a intermediate topic in Thermodynamics & Energetics. It builds on the vocabulary of beginner topics in this area.
What should I learn before Coffee-Cup Calorimeter?
Study these earlier topics in Thermodynamics & Energetics first: Molar Heat Capacity, Calorimetry, Bomb Calorimeter.
What comes after Coffee-Cup Calorimeter?
The next topics in Thermodynamics & Energetics are Thermochemical Equation and Standard Enthalpy of Formation.
Can I practise Coffee-Cup Calorimeter with quizzes?
Yes. The interactive lesson includes a self-check question on Coffee-Cup Calorimeter, and the Thermodynamics & Energetics quiz draws on every topic in this area.
Where Coffee-Cup Calorimeter fits in Thermodynamics & Energetics
Coffee-Cup Calorimeter is topic 17 of 91 in Thermodynamics & Energetics.