Thermochemistry

Conversion factors for heat

1 Cal/kcal = 1000 cal = 4.184 KJ = 4184 joules

Chemical Potential Energy

Energy stored in chemicals

Endothermic

Heat goes into the system, making the surroundings cooler

Exothermic

Heat goes into surroundings, exiting the system

Specific Heat

Amount of heat required for a substance to be raised one degree Celsius for one gram

Enthalpy (H)

Amount of heat a substance has at a given temperature and pressure

Calorimetry

Instrument that measures the gain or loss of heat

Phase Change

Transition between solid, liquid, and gas states

Molar Heat of Fusion

Energy required to melt 1 mole of a solid substance

Molar Heat of Vaporization

Heat needed to change the phase from liquid to gas

Heating Curve

Graph showing changes in temperature and phase transitions

Standard Enthalpy of Formation

Heat change when one mole of a compound is formed from its elements

Standard Enthalpy of Reaction

Enthalpy of a reaction carried out at 1 atm

Hess’s Law

Total enthalpy change is the same regardless of the reaction pathway

How to calculate the enthalpy (heat) of reaction?

products - reactants

What does the negative sign mean?

when do I put it and when do I not based on the question?

it means energy released or exergonic

use it when it asks what happebns to the energy,

when it says how much energy is released or anything else telling us its already exergonic, do not put the negative sign

Metric Conversions

K H D M D C M

Kili, Hecto, Deca, Meter (base), deci, centi, milli

How to determine t he specific heat of an object with calorimetry?

heat lost by object = =heat gained by water

Hotter= -cooler

What does a calorimeter do and how?

calorimeter can be used to determine the specific heat of

a substance, or to determine the heat given off or absorbed

by a chemical rxn.

a process is determined by

measuring the heat change in

the water surrounding the process

in an insulated container called

a calorimeter.

Fusion vs solidification

vaporization vs condensation

which releases energy, which needs energy

if one object was same temp as another but one had more mass than the other

which has more energy

the one with more mass

which objects usually have higher specific heat, which dont

larger molecules have a higher specific heat

water has one of the highest specific heats

metals have low specific heat

heat vs tempeature

what does enthalpy mean

disorder

or energy

how do i find limiting reagent

with the 2 values given, use stociometry to find how much of a specific product they can produce mol/mol

the one with the least is the limiting reagent and that will be used to find how m,uch energy for that amo

properties of high specific heat

properties of low specific heat

high - retain heat longer, takes longer to heat up

low - transfers heat fast