General Chemistry 2 Flashcards
The study Of energy or heat Flow that accompanies a chemical reaction and/or physical transformation
THERMOCHEMISTRY
a Form Of energy transfer between two objects as a result of their difference in temperature
HEAT
the part of the universe being studied or to which attention Is Focused
SYSTEM
include everything else in the universe
SURROUNDING
Heat is represented by this letter
q
heat flows From a system to its surroundings; - q
EXOTHERMIC
system absorbs heat From surroundings; +q
ENDOTHERMIC
a branch of thermodynamics, which deals with the interconversion of energy between two forms: heat & work
THERMOCHEMISTRY
States that energy can neither be created nor destroyed, It can only be transferred between the system and surroundings
LAW OF CONSERVATION OF ENERGY
Based on the first law of thermodynamics, the equation on the change in energy Of a system
E = q + w
q = heat absorbed, w = work done
Involves the measurement of the quantity of heat exchanged between a system and its surroundings
CALORIMETRY
measures the Flow of energy (as heat) between the system and its surroundings
CALORIMETRY
The amount of heat absorbed or released by the system is a function of its change in temperature
q = C∆t
q = heat (J)
∆t = change in temp. (°C)
Proportionality constant that shows the relationship between heat and temp. change. Also the amount of energy needed to raise the temp. of a substance by 1°C. (J/°C)
Heat Capacity (C)
Heat Capacity is equal to the product of its _____ and _____.
mass (m), specific heat (c)
C = mc
The amount of energy needed to increase the temp. of one gram of a substance by 1°C. (J/g°C). Also, it is constant for some substances.
Specific Heat (c)
An insulator apparatus that contains water or liquid of known heat capacity. It determines the heat capacity of a substance.
Calorimeter
The System of a Calorimeter is composed of two parts:
Substance and Chemical Reaction
Heat exchange in a calorimeter is expressed as (when the calorimeter is an excellent insulator and absorbs only a negligible amount of heat)?
q (sys) = - q (water)
or
q (sys) = - mc∆t (water)
A typical calorimeter used in experimentation which is usually made with a polystyrene cup that is a good insulator.
Coffee-Cup Calorimeter
Parts of a Coffee-Cup Calorimeter
Thermometer and Stirrer
Total Heat Transferred (absorbed or released) in a chemical reaction at constant pressure, and often referred to as Heat Content.
Enthalpy (H)
A Balanced Equation that also specifies Heat Flow for the reaction.
Thermochemical Equations
Expresses a quantitative relationship between the amounts of substances that react and the heat of the reaction
Thermochemical Equations
In writing a Thermochemical Equation, where is the heat flow listed beside the balanced chemical equation?
In the right side
aA + bB —> cC ∆H = ___kJ
___ is directly proportional to the quantity of a substance that reacts or is produced by the reaction. If the coefficients in an equation are doubled, the value of ___ is multiplied by 2.
∆H
∆H that accompanies a chemical reaction; is the net energy change resulting from the breaking and formation of bonds.
Heat of Reaction
The Heat of reaction can be solved using the equation:
∆H°rxn = Σ∆H°f (products) - Σ∆H°f (reactants)
The change in enthalpy when the compound was formed from its elements under standard conditions.
Enthalpy of Formation
