Types of Energy and Their Uses Flashcards
system
the chemical components involved in a process
the component
whatever you are examining
surroundings
everything outside the system
whatever is coming in contact with the system
exothermic reaction
negative
A reaction that releases heat into its surroundings
the reactants are more than the products
keywords: produces, releases
endothermic reaction
positive
A process or chemical reaction that absorbs heat from the surroundings
the reactants are less than the products
keywords: absorbs,
energy
the ability of a substance to move or do work
potential energy
an object that has the ability to move in the future
the energy owned by an object for the reason of its position
For example a yoyo before it is released, a car that is parked at the top of a hill
Sound, heat, and light are not easily classified as this
kinetic energy
the energy of an object in respect to its motion
example, a fan circulation on a warm day, a glass shattering on the floor after it falls from the counter
Truth, peace, and justice are not examples of this
radiant energy
the energy that is transferred by electromagnetic radiation
example the warmth that radiants form a hot stove, warmth from the sun
chemical energy
energy stored in the bonds of chemical compounds
energy is released when a chemical reaction takes place, and once the energy is released, the substance is transformed into a whole new substance
the energy necessary to keep atoms joined by chemical bonds
Explosives - as explosives go off, chemical energy stored in the explosive is transferred into sound energy
Placing a metal pole outside in the sunlight is not an example of this
law of conservation of energy
the law that energy can be neither created nor destroyed but may be converted from one form to another
temperature
the measure of average kinetic energy of the particles
heat
is thermal energy transferred from one substance to another substance with a lower temperature
specific heat capacity
the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree or one Kelvin
this is more specific to size amount compared to heat capacity
heat capacity
amount of heat required to raise the temperature of an object by 1 degree celsius or one kelvin
thermal equalibrium
if we have two objects that are different temperatures connected, eventually they will be the same temperature
when two objects are in contact, heat travels from the warmer object to the colder object until their temperatures are the same
this is when if you connect two bodies by a pipe and no heat will flow between them
for example, if a carton of milk is set on a kitchen countertop, the two objects are in thermal contact. After several hours their temperatures will become the same so they are in thermal equalibrium
what is an equation that calculates quantities of heat
q=mc delta t
Q=quantity of heat in joules
m=mass of the substance in grams
c=specfic heat capacity always given the triple J/g times C
delta t= difference in final temperature to the initial temperature in celsius
thermochemical equation formula
ni/nf=deltaHi/deltaH2
ni= mols given in the equation
nf=mols given in the word problem
H=change in enthalpy
H2=n2 multiplied by H1/n1
enthalpy
the heat content of a system
every substance involved in a chemical reaction or a physical process has a particular heat content
calorimetry
used to measure the amount of heat transferred to a form a substance
qsystem=-qsurroundings
heat of the system is always the opposite sign of heat of the surroundings
diatomic molecule acronym
HONClBrIF
Hess’s law
the enthalpy change for any reaction depends only on the products and the reactants and is independent of the pathway or the number of steps between the reactant and the product
According to Hess’s law since, we’re adding equations one and two to get equation three, the enthalpy change and the answer is the sum of the enthalpy changes of the equations you’re adding up
key takeaway: using enthalpy change of other reactants to predict the enthalpy change of a new reaction
heat calculation steps
- state what is given, and convert the given variables accordingly keeping in mind that mass is in g, specific heat is in J/g C, the change in temperature is in celsius, q or change in h is in J
- use formula q=mc change in t, rearrange the equation if needed and in the numbers
- put the answer in scientific notation
thermochemical equation steps mols to grams
use the chart method
thermochemical equation steps mols given
- underline the element you’re focusing on, then state what is given
- use the formula n1/n2=change in h1/change in h2 where n1 is the mols in the equation, n2 is the mols in the word problem, change in h1 is the delta h given, and change in h2 is the quantity you’re trying to find
- cross multiply to make it look stoichiometric
- round final answer to scientific notation
thermochemical equation steps grams to mols
- state what is given
- convert grams to mols by diving the mass by the molar mass using the chart technique, then multiply the delta h given by the mols given in the equation
- round final answer in scientific notation
formation of magnesium oxide reaction progress
the reactants are more than the products
simple decomposition of liquid water reaction progress
the products are less than the reactants
molar heat
the temperature of one mole of a substance by one Celsius degree or one kelvin’
molar heat capacity=specific capacity multiplied by molar mass
calorimeter
a tool used the measure the enthalpy change of a chemical or physical reaction
it works by insulating a system from its surroundings. by measuring the temperature change of the system, you can measure the amount of heat that is released or absorbed by the reaction
