Energy in Chemical reactions
scale
a series of marks and numbers that is used for measurement
in what type of reaction or process does heat flow into the system
endothermic
electromagnetic energy
energy associated with electric fields, magnetic fields, and electromagnetic radiation
joule
the SI unit of energy
molar heat of fusion
the amount of heat required to melt one mole of a substance
which event is endothermic
the melting of ice
the part of total internal energy that can be transferred
thermal energy
which shows the formula for converting from degrees celsius to degrees fahrenheit
*F=(9/5 x *C)+32
carmen is heating some water and trying to measure the temperature of water using a celsius thermometer. which measurement can she expect once the water begins to boi
100*C
which statement defines calorimeter
a device that measures the heat that is gained or lost in a chemical change
calorimeter
a device used to measure the heat absorbed or evolved during a physical or chemical change
conduction
a heat transfer that involved direct contact between two substances so there can be collisions between molecules
hess's law
a law that states that if a series of reactions are combined, the enthalpy change for the reaction is the sum of the enthalpy changes for the individual reactions
enthalpy (H)
a measure of heat and internal energy in a system
temperature
a measure of the average kinetic energy of the particles in a substance
what is the definition of entropy
a measure of the overall disorder of a system
which is the best example of how electromagnetic energy is used in everyday life
a patient receiving an x-ray in a hospital
which answer defines exothermic reaction
a process in which energy is released as heat
state function
a quantity whose change in magnitude during a process depends only on the beginning and end points of the process, not on the path taken between them
open system
a system that can exchange both matter and energy with its surroundings
closed system
a system that can exchange energy, but not matter, with its surroundings
absolute zero
a theoretical temperature at which the motion of all atoms and molecules stops
what scientific tool would be the most helpful when measuring the temperature of a substance that is undergoing a phase change
a thermometer
thermometer
a tool used to measure temperature
calorie
a unit of energy eqal to 4.18 J
the coldest possible temperature
absolute zero
how does the potential-energy diagram for a reaction indicate whether the reaction is endothermic or exothermic
an endothermic reaction has reactants that are lower in energy than products because energy is absorbed to form the products
which type of reaction is always spontaneous
an exothermic reaction that has an increase in disorder
how should the baking of a pizza be categorized
as an endothermic process because the dough absorbs heat
iron reacts with oxygen in a chemical hand-warmer. how should this reaction be categorized
as an exothermic process because it releases heat
an ice cube is dropped into a glass of milk at 20*C. which statement explains the transfer of kinetic energy (KE)
because milk has higher KE than ice, KE is transferred from the milk to the molecules of ice
digby wants to determine how many calories are his bag of chips. which calorimeter should he use
bomb calorimeter
a welding torch produces a flame by burning acetylene fuel in the presence of oxygen. this flame is used to melt a metal. which energy transformation represents this process
chemical energy into thermal energy
old photographic flashbulbs burn magnesium metal in a reaction that causes a flash of brilliant white light. a photographer would need to take care not to suffer burned fingers when trying to replace the hot bulb. what best identifies the energy transformation that occurs in the flashbulb
chemical energy to electromagnetic energy and thermal energy
juan measured the temperature of salt water. he then added 273 to the measured value. which conversion is juan most likely doing
degrees celsius to kelvins
endothermic
describing a process that involves the absorption of energy from the surroundings by substances undergoing change
exothermic
describing a process that involves the release of energy into the surroundings by substances undergoing change
when ammonium chloride is dissolved in water, the beaker gets cold. which type of reaction does this describe
endothermic
which statement describes the law of conservation of energy
energy cannot be created nor destroyed, but it changes from one form to another
which energy changes are associated with a liquid freezing
energy is released as potential energy decreases
which statement is correct about the law of conservation of energy
energy is transferred when atoms are rearranged
chemical energy
energy stored in chemical bonds
energy (2)
energy that flows from a warmer object or substance to a cooler object or substance
a metal sample is heated and placed into water in a calorimeter at room temperature. which statement best describes how the calorimeter can be used to determine the specific heat capacity of the metal sample
energy transfers from the metal to the water and calorimeter until they all reach a single temperature
two metal blocks that have slightly different temperatures are placed next to one another. after five minutes, they both have lower but equal temperatures. according to the law of conservation of energy, what most likely happened
energy was transferred from the warmer block to the cooler block
according to the law of conservation of energy, what will most likely happen in a closed system
energy will be exchanged, but matter will not exchanged
the specific heat of water is 4.18 J/(g*C) and that of wood is 1.97 J/(g*C). which statement is correct
given equal masses, water will heat up less than wood if the same heat is added
energy that flows from a warmer object or substance to a cooler object or substance
heat
which is the best example of potential energy
holding a basketball in the air
the sum of potential and kinetic energies in the particles of a substance is called ____ energy
internal
chemical energy in burning wood is changed into thermal energy. the thermal energy is absorbed by water, which boils to produce steam. the thermal energy is changed into kinetic energy in the moving steam. the kinetic energy is used to turn a turbine, which converts the kinetic energy into electricity. which sentence best describes this system
it involves both energy transformation and energy transfer
when two intermediate chemical equations are combined, the same substance that appears in the same phase can be canceled out provided that
it is a reactant in one intermediate reaction and a product in the other
which describes the enthalpy change associated with an endothermic reaction
it is positive because the enthalpy of the products is greater than the enthalpy of the reactants
which statement about /\Hf is true
it is positive when the bonds of the product store more energy than those of reactants
which best describes thermal energy
it is the portion of internal energy that can be transferred from one substance to another
which statement describes how a basic coffee cup calorimeter works
it uses the mass and specific heat of water along with a thermometer to measure the gain or loss of energy when a substance is added
how is kinetic energy of the particles of a substance affected during a phase change
kinetic energy doesn't change but the potential energy does
what happens to energy when sally kicks a soccer ball
kinetic energy is transferred from the leg to the soccer ball
what type of energy is the sum of an object's potential and kinetic energy
mechanical energy
a generator contains a coil that spins to produce an electric current. how is energy transformed by using a generator
mechanical energy is transformed to electromagnetic energy
which term is used to describe the amount of heat that is required to convert 1 mol of a liquid to a gas
molar heat of vaporization
a baker touches a pie right after taking it out of the oven. which statement best explains why the pie feels hot
molecules in the pie move faster than molecules in the skin, so heat is transferred to the skin
which of these results in kinetic energy of an object
motion
how should the enthalpy of an intermediate step be manipulated when used to produce an overall chemical
multiply the enthalpy by -1 if the chemical equation is reversed
heat that flows by conduction is the transfer of thermal energy between substances in contact. what must occur for this to happen
one system must have higher kinetic energy than the other system
when an object falls toward the ground due to gravity, what type of energy becomes kinetic energy
potential
during an endothermic phase change, what happens to the potential energy and the kinetic energy
potential energy increases and kinetic energy stays the same
which statement describes spontaneous processes
proceed without continuous external influence and have an overall negative free energy change
which statement about spontaneous and nonspontaneous processes is correct
spontaneous processes are favored by a decrease in /\H, but nonspontaneous reactions are favored by an increase in /\H
which process is spontaneous
spreading of a strong fragrance of perfume in a room
which defines the average kinetic energy of a system's particles
temperature
energy
the ability to do work or cause change
molar heat of vaporization
the amount of heat required to vaporize one mole of a substance
two samples of carbon come into contact. a heat transfer will occur between sample A and sample B. what must be true for heat to transfer from sample A to sample B
the average energy of A is greater than that of B
the temperature of a gas is increase. which statement best explains the effect that this has on the motion of gas particles
the average kinetic energy increases, and the particles collide more frequently
thermochemical equation
the chemical equation that shows the state of each substance involved and the energy change involved in a reaction
enthalpy of reaction
the energy absorbed or released during a chemical reaction
enthalpy of formation
the energy absorbed or released when a pure substance forms from elements in their standard states
kinetic energy
the energy associated with movement
potential energy
the energy associated with position
enthalpy of combustion
the enthalpy of reaction for a combustion reaction, typically of a hydrocarbon
thermal energy
the kinetic energies of the molecules making up a substance
law of conservation of mass
the law stating that energy cannot be created or destroyed but it can change from one form to another
which of these indicates that a liquid has transferred thermal energy to the air
the liquid decreases in temperature and its particles lose kinetic energy
a thermometer is placed in water in order to measure the water's temperature. what would cause the liquid in the thermometer to rise
the molecules in the thermometer's liquid spread apart
standard state
the natural state of an element at 1 atm and 25*C
a book is falling from the top shelf of a bookcase, which statement correctly describes the change in the energy of the book
the potential energy decreases as kinetic energy increases
heat capacity
the quantity of heat needed to raise the temperature of a given sample of a substance by one degree celsius (kelvin)
specific heat capacity
the quantity of heat required to raise the temperature of one gram of a substance by one degree celsius (kelvin) at constant pressure
which statement defines specific heat capacity for a given sample
the quantity of heat that is required to raise 1 g of the sample by 1*C (kelvin) at a constant pressure
which statement defines the heat capacity of a sample
the quantity of heat that is required to raise the sample's temperature by 1*C (or Kelvin)
which statement is true if the /\Hrxn of a reaction is positive
the reaction is endothermic
mechanical energy
the sum of the kinetic and potential energy of an object
which statement describes a system that consists of sugar crystals in water
the system becomes more disordered and has an increase in entropy
what is enthalpy
the total heat content of the system
internal energy
the total potential and kinetic energies of the particles in a substance
heat
the transfer of kinetic energy between molecules as faster-moving molecules collide with slower-moving molecules
heat (1)
the transfer of kinetic energy between molecules as faster-moving molecules collide with slower-moving molecules
which statement describes mechanical energy
the type of energy that is associated with electromagnetic radiation
calorimetry
the use of a calorimeter to measure energy given off or absorbed during a physical or chemical process
what causes the air above a pot of boiling water to become warm
the water vapor transfers thermal energy to the air
energy that can flow as heat
thermal energy
convert
to change from one form to another
which process involves a decrease in entropy
water freezing into ice
which shows the temperatures of three substances, in order, from greatest to least
water vapor, water, ice