Chemistry Thermochemistry

energy

the capacity to supply heat or do work

enthalpy

the heat content of a system

chemical potential energy

the energy stored in the chemical bonds of a substance

heat of reaction

the energy that is released or absorbed when chemicals are transformed in a chemical reaction

heat

thermal energy transferred between two systems at different temperatures that come in contact

heat of combustion

the amount of heat released during the process of oxidation or combustion

thermochemistry

the study of the heat energy which is associated with chemical reactions and/or phase changes such as melting and boiling

heat of fusion

heat required to melt a solid; specifically the amount required to melt unit mass of a substance at standard pressure

law of conservation of energy

energy can neither be created nor be destroyed

heat of solidification

the heat liberated by a unit mass of liquid at its freezing point as it solidifies: equal to the heat of fusion

specific heat (capacity)

the quantity of heat needed to raise the temperature per unit mass

heat of vaporization

the amount of heat needed to turn 1 g of a liquid into a vapor, without a rise in the temperature of the liquid

endothermic

chemical reactions in which the reactants absorb heat energy from the surroundings to form products

heat of condensation

heat evolved when a vapor changes to a liquid

exothermic

a chemical reaction that releases energy in the form of heat, light, sound, or electricity

heat of solution

the quantity of heat evolved or absorbed in the dissolution of one gram-molecule of substance in a quantity of solvent so large that any further dilution would cause no thermal effect

system

a collection of objects (or smaller systems) that can be identified

Standard heat of formation

the change of enthalpy during the formation of 1 mole of the substance from its constituent elements in their reference state, with all substances in their standard states

surroundings

everything that is not directly involved in the reaction

Hess's law

if a process can be expressed as the sum of two or more steps, the enthalpy change for the overall process is the sum of the ΔH values for each step

calorimeter

a device used to measure the amount of heat involved in a chemical or physical process

explain the difference between heat and temperature

temperature is a measurement of the average kinetic energy of particles in an object.

explain specific heat capacity and how different values affect the properties of materials

Specific heat capacity represents how much heat energy is needed to raise the temperature of a substance by one degree Celsius (or one Kelvin) per unit mass. It's like a unique fingerprint for each material, revealing how well it "holds onto" or "releases" heat. Materials with high specific heat capacity can absorb large amounts of heat without significant temperature changes, while those with low specific heat capacity heat up and cool down quickly.

explain the difference between endothermic and exothermic processes and how they affect the system and surroundings

endothermic reactions absorb energy from the surrounding that is in the form of heat. On the other hand, an exothermic reaction releases energy into the surroundings of the system

explain how a calorimeter works

when an exothermic reaction occurs in solution in a calorimeter, the heat produced by the reaction is absorbed by the solution, which increases its temperature