All matter contains...
energy
Whenever matter undergoes a change, what also changes...?
the quantity of energy that matter contains
What is a candle's source of energy...?
paraffin wax (a hydrocarbon)
What is the purpose of a candle's wick...?
it absorbs liquid paraffin wax and fuels the fire
What does the fire of a candle do to liquid wax...?
it vaporizes it
What is actually burning in a candle...?
paraffin wax vapor
What are the two higher energy reactants of a burning candle...?
paraffin wax (a hydrocarbon) & oxygen gas (O2)
What are the two lower energy products of a candle burning...?
carbon dioxide (CO2) & water (H2O)
In the chemical reaction of a candle burning, the difference in energy is released as...?
heat & light
When heat is absorbed by lower energy ice, from a candle for example, it becomes...?
higher energy water
A candle burning is what type of reaction...? As seen by...?
exothermic. as seen by heat and light
Ice being heated by a candle is what type of reaction...? As seen by...?
endothermic. as seen by melting
In a thunderstorm, what are the lower energy reactants...?
nitrogen gas (N2) & oxygen (O2)
Lightning in a thunder storm causes nitrogen gas and oxygen to do what three things...?
absorb energy, react by combustion, and form nitric oxide (NO)
Where does nitrogen gas (N2) and oxygen (O2) absorb energy from, during oxidation by lightening...?
from high energy water vapor
During a thunderstorm, high energy water vapor releases energy and...?
condenses to form lower energy liquid water (rain)
Matter can do what three things to energy...?
release energy, absorb energy, or alter the flow of energy
Fuels, such as oil and wood, do what with energy...?
release it
What does fertilizer do for plants...?
helps plants absorb solar energy
The study of energy and its transformations...?
Thermodynamics
The branch of thermodynamics that deals with heat in chemical and physical change...?
Thermochemistry
Heat is also known as...?
thermal energy
Energy always flows between a system and its surroundings in the form of what two things...?
heat (q) or work (w)
Because energy always flows between a system and its surroundings in the form of heat or work, total energy is...?
always conserved
The total size of an energy change, does not depend on...?
how the change occurs
The heat of a reaction in an open container is identified as a change in...?
enthalpy (H)
What is enthalpy (H)...?
the TOTAL HEAT content of a SYSTEM (kJ/mol)
Reactions with a negative change in enthalpy (-?H) are known as...?
exothermic reactions
Reactions with a positive change in enthalpy (+?H) are known as...?
endothermic reaction
What does a calorimeter measure...?
the amount of heat (q) involved in a chemical reaction
The quantity of heat (q) in a reaction, is proportional to...?
the amounts of substances
All energy is found in what two interconvertible forms...?
potential & kinetic energy
The energy transferred when an object is moved by a force is known as...?
work (w)
A weight falling, hitting the floor, and moving pebbles and soil slightly, is an example of...?
work (w)
The weight landing on the floor, warming the pebbles and soil slightly, is an example of...?
heat (q)
When energy is transferred from one object to another, it appears as...?
work (w) &/or heat (q)
In any thermodynamic study, including measuring a change in energy (?E), the first step is to define...?
the system
The system is the...?
part of the universe we are focussing on
The moment we define the system, everything else is defined as...?
the surroundings
In principle the rest of the universe is the surroundings. But in practice, we consider only the parts that are...?
relevant to the system
Each particle in a system has what two things...?
potential & kinetic energy
The sum of all the energies, potential and kinetic, of all particles of the system, is known as the...?
internal energy (E)
When the reactants in a chemical system change to products, what else changes...?
the system's internal energy (E) changes
The change in internal energy (?E), is the difference between...?
the final internal energy (E final) & the initial internal energy (E initial)
?E = E final - E initial =
E products (final state) - E reactants (initial state)
Because the universe consists of only system and surroundings, a change in the energy of the system must be accompanied by an equal and opposite change...?
in energy of the surroundings
In an energy diagram, the final and initial states of a system are seen as...?
horizontal lines
A system can change its internal energy by what two ways...?
by releasing some energy in a transfer TO the surroundings (-?E), or by absorbing some energy in a transfer FROM the surroundings (+?E)
In an exothermic reaction, E products is...?
less than E initial
In an endothermic reaction, E products is...?
more than E initial
?E is a transfer of energy from...?
system to surroundings, or vice-versa
All energy is transferred from system to surroundings or vice versa in what two forms...?
Heat (q) & Work (w)
Heat (q) is the energy transferred as a result in...?
temperature difference between the system and the surroundings
Why is energy in the form of heat transferred from soup (system) to the bowl, air, and table (surroundings)...?
because they are at a lower temperature
Work (w) is the energy transferred when...?
an object is moved by a force
When you kick a ball a great distance, what is the system and what are the surroundings...?
the system is you, the kicker. and the surroundings are the ball and air.
When you pump up a ball and it expands, what is the system, and what is the surroundings...?
the added air is the system. and the inner wall of the ball that is expanding is the surrounding.
The total change in a system's internal energy is the sum of...?
the energy transferred as heat and work
?E = ?
?E = q + w
When ?E is positive "+" energy was transferred...?
into the system
When ?E is negative "-" energy was transferred...?
out of the system
For a system that transfers energy only as heat (w=0), the equation is...?
?E = q
What would the sign of ?E be for hot water (system) sitting in a beaker, in a room temp. lab...? because...?
- negative. because heat was released from the system to the surroundings (-q) & no work was done (w=0).
What would the sign of ?E for ice water (system) sitting in a beaker, in a room temp. lab...? because...?
+ positive. because heat was absorbed by the system from the surroundings (+q) & no work was done (w=0).
For a system that transfers energy only as work (q=0), the equation is...?
?E = w
What would the sign of ?E be for HCl (l) and Zn (s) (system) reacting to form H2 (g) which pushes a piston in an insulated/ evacuated container (q=0)...? because...?
- negative. because work was done by the system to the surroundings (+w) & no heat was transferred (q=0).
What would the sign of ?E be for a piston (surrounding) moving into the a evacuated/ insulated container of formed H2 (g) and increasing the pressure...? because...?
+ positive. because work was done on a system by the surroundings (+w) & no heat was transferred (q=0).
When a system absorbs energy, the surroundings...?
release it
When a system releases energy, the surroundings...?
absorb it
Energy transferred to the surroundings can be in the form of heat or various types of...?
work (w)
Mechanical, electrical, radiant, and chemical are all forms of various types of...?
work (w)
The work done by gasoline burning (system) to the surroundings, is converted to mechanical energy when...?
turning the car's wheels and belts
The work done by gasoline burning (system) to the surroundings, is converted to electrical energy when...? (3 things)
powering the sound system, radiant energy of the lights, & chemical energy of the battery
How do cars increase gas mileage in relation to heat (q) exchange...?
by insulation. which reduces heat loss to surroundings and increases work done by system to surroundings (car)
During photosynthesis, work (w) can be seen by plants converting solar energy into...? in the form of...?
chemical energy. in the form of bonds between starch and O2
During aerobic respiration, work (w) can be seen as the chemical energy in the bonds of foods converting to...? in the form of...?
mechanical energy. in the form muscular contractions.
Because aerobic respiration is not 100% efficient in the conversion of work, what is lost...?
heat (q)
The first law of thermodynamics is also known as...?
law of conservation of energy
The law of conservation of energy states what two things...?
the total energy of the universe is constant (?E universe = 0). and energy cannot be rested or destroyed (energy is conserved)
The law of conservation of energy (first law of thermodynamics) is expressed mathematically as...?
?E universe = ?E system - ?E surroundings = 0
The SI unit of energy is the...?
joule (J)
The joule (J) is a derived unit composed of what three basic units...? (1 J = ?)
1 J = 1 kg
m^2
s^-2
Both heat (q) and work (w) are expressed in...?
joules (J)
Work (w) is the product of what three things...?
mass
acceleration (F = m
a) * distance
The calorie (cal) is an older unit defined originally as the quantity of energy needed to...?
raise 1 g of H20 by 1� C
1 calorie (cal) is qual to how many joules (J)...?
1 cal = 4.184 J
4.184 J = ?
1 cal
Since the quantities of energy involved in chemical reactions are usually quite large, chemists is the (unit)...?
kilojoule (kJ)
What part of a car is used for removing excess heat from internal combustion engines...?
the radiator
The British thermal unit is the energy required to...?
raise 1 lb of H20 by 1� F
1 Btu = how many joules...?
1 Btu = 1055 J
A property that is dependent on the CURRENT state of the system is known as a...?
state function
A state function is NOT dependent on...?
the path the system takes to reach that state
What are four examples of state functions...?
change in internal energy (?E), change in pressure (?P), change in volume (?V), & change in temperature (?T)
?E does NOT depend on how the change takes place, but only on the difference between...?
the final & initial states
What is the chemical equation for the gasoline component 'octane'...?
C8H18 (octane)
What are two properties that are NOT state functions...?
heat (q) & work (w)
Heat (q) and work (w) are NOT state functions, because their values...?
DO depend on the path the system takes
An example of heat (q) and work (w) not being a state function, can be seen with octane burning what two ways...?
it can burn in an open container and give of solely heat. or can burn in an engine and produce work and heat.
Internal energy (E) is transferred as heat (q) when...?
the system and surroundings are at different temperatures
Internal energy (E) is transferred as work (w) when...?
an object is moved by a force
The same overall change in internal energy (?E) can occur through any combination of...?
heat (q) or work (w)
What thermodynamic variable is related directly to energy changes at constant atmospheric pressure...?
enthalpy (H)
What are the two most important types of chemical work...?
electrical work, & pressure-volume work (PV work)
Pressure-volume work, is the mechanical work done when the volume of the system changes in the presence of...?
an external pressure (P)
The quantity of PV work equals the product of what two things...?
pressure ( P) times the change in volume (?V)
The equation for PV work (w) done ON the surroundings has the equation...?
w = - P ?V
What is change in enthalpy (?H)...?
changes in energy of a system at constant pressure
What is the equation for enthalpy (H)...?
H = E + PV
What is the equation for the change in enthalpy (?H)...?
?H = ?E + P ?V
The change in enthalpy (?H) is also equal to...?
the heat absorbed or released at constant pressure (q little-P)
For most changes occurring at constant pressure, what is more relevant and easier to obtain...?
?H. as apposed to ?E
To find change in enthalpy (?H), find...?
heat at constant pressure (q little-P)
In reactions that do not involve gases, the change in enthalpy (?H) is approximately equal to...? because...?
the change in internal energy (?E). because solids and liquids undergo VERY little volume change.
In reactions in which the amount of mol of gas does not change, the change in enthalpy (?H) is equal to...? because...?
the change in internal energy (?E). because the volume of the total gas did not change.
In reactions in which the amount of mol of gas DOES change, the change in enthalpy (?H) is approximately equal to...? because...?
change in internal energy (?E). because the change in volume is VERY small compared to the change in heat (q little-P)
Thus, for most reactions, ?H equals, or is very close to...?
?E
Because enthalpy (H) is a combination of E, P, and V, it is considered a...?
state function
Because change in enthalpy (?H) is a state function, path independent, it can be defined as...?
?H = H products - H reactants
Since H products can be either more or less than H reactants, the sign of ?H indicates whether...?
heat is absorbed or released during the reaction
A negative change in enthalpy (-?H) indicates...?
an exothermic reaction
The combustion of methane (CH4) would have what sign of ?H...?
- negative
A positive change in enthalpy (+?H) indicates...?
an endothermic reaction
What is the chemical equation for methane...?
CH4 (methane)
In general, the value of enthalpy change (?H) is determined with reactants and products at the same pressure and...?
temperature
In an enthalpy diagram, enthalpy values are seen as...?
horizontal lines
The quantity of heat (q) absorbed or released by an object is proportional to...?
its temperature change
The heat (q) divided by the change in temperature (?T) of an object is always...?
constant
heat (q) divided by the change in temperature (?T) for an object is equal to...?
heat capacity [SI: J/K]
Heat capacity is the heat required to...?
raise an object's temperature by 1 K
Specific heat capacity (c) is the quantity of heat needed to...?
raise 1 g of an object by 1 K
The specific heat capacity of an object (c) is equal to...?
c = q / m * ?T
What is the SI unit for specific heat capacity (c)...?
J / g * K
The heat (q) absorbed or released by an object is equal to the product of what three values...?
mass (m), specific heat capacity ( c ), & change in temperature (?T)
Molar heat capacity ( C ) is defined as the quantity of heat needed to...?
raise 1 mol of a substance by 1 K
Molar heat capacity ( C ) is equal to...?
q / mol * ?T
What is the SI unit for molar heat capacity ( C )...?
J / mol * K
How do you find the molar heat capacity ( C ) of a substance only given the specific heat capacity ( c )...?
multiply specific heat capacity ( c ) by molar mass of substance
Ethylene glycol ( (CH2OH)2 ) is a common component of what automobile substance...? found in...?
antifreeze found in the radiator/ cooling system.
What device is used to measure the heat released or absorbed by a chemical or physical process...?
a calorimeter
For processes that take place at constant pressure, the heat transferred (q little-P) is often measured in...?
a coffee-cup calorimeter
Molarity (M) can also be expressed as...?
mol/ L
How do you find the number of moles of a substance (mol), given molarity (M) and volume (V)...?
mol = M * V
Constant-volume calorimetry is often carried out in what device that is more precise than a coffee-cup calorimeter...?
a bomb calorimeter
What value is generally known in bomb calorimetry...?
the heat capacity of the entire calorimeter
Although a bomb calorimeter is not exposed to atmospheric constant pressure, q obtained is at...?
constant volume (q little-V)
Heat at constant volume (q little-V) does not equal change in enthalpy (?H), but rather equals...?
change in internal energy (?E)
At constant pressure, heat (q) absorbed or released by a system is recorded with a...?
coffe-cup calorimeter (q little-P = ?H)
At constant volume, heat (q) absorbed or released by a system is recorded with a...?
bomb calorimeter (q little-V = ?E)
A balanced chemical equation that includes the enthalpy change of the reaction (?H) is known as a...?
thermochemical equation
The ?H associated with thermochemical equations is relevant only to way two things...?
the states of matter & the amounts (mol) of substances in that equation
What aluminum or is the world's greatest source of aluminum...?
bauxite
A chemical decomposition caused by heat, such as aluminum oxide in bauxite to oxygen and aluminum, is known as...?
thermal decomposition
In practice, aluminum is actually obtained by supplying what to bauxite (aluminum oxide)...?
electrical energy
If ?H in a thermochemical equation is positive, then the products have...?
absorbed that given energy (?H) per given number of moles
The equation "2 H20 (l) -> 2 H2 (g) + O2 (g) ?H = 572 kJ" indicates that 2 moles of H2 (g) have...?
absorbed 572 kJ of energy
What is the chemical equation for the unsaturated organic compound ethene...?
C2H4 (ethene)
Hydrogenation of ethene (C2H4 or H2C=CH2) forms...?
ethane (C2H6 or H3C-CH3)
The sign of a ?H for a forward reaction is opposite that, for...?
the reverse reaction
What law states that the enthalpy change of an overall process is the sum of the enthalpy changes of its individual steps...?
Hess's law
Hess's law is made possible because enthalpy (H) is a...?
state-function
What two pollutants form initially during auto exhaust...?
carbon monoxide (CO) & nitric oxide (NO)
Carbon monoxide (CO) and nitric oxide (NO) from auto exhaust are converted to what two less harmful gases...?
carbon dioxide (CO2) & nitrogen gas (N2)
Dinitrogen pentoxide (N2O5) is also known as simply...?
nitrogen pentoxide (N2O5)
In order to study and compare retains, chemists have established a set of specific conditions called...?
standard states
For a gas, the standard state is what pressure...?
1 atm (or 1 bar)
For a substance in aqueous solution, the standard state is what concentration...?
1 M (mol/L) concentration
For a pure substance, the standard state is usually...? and at what temp...?
the most stable form of that substance. and at 25�C or 298 K
What does the degree sign (�) indicate...?
the variable was found at standard states (standard-state symbol)
When the enthalpy change of a reaction is measured at standard state, it is known as the...?
standard enthalpy of reaction (?H�rxn) (or "standard heat of reaction")
In a formation equation, 1 mol of a compound forms from...?
its elements in their standard states
Most compounds have a negative ?H�f, meaning in most formations of compounds from their elements...?
heat is released (exothermic)