energy released in a chemical reaction comes from _________ that is contained in chemical _____
chemical energy, bonds
breaking a chemical bond __________ energy from the surroundings
absorbs
forming a chemical bond _________energy to the surroundings
releases
the energy in chemical bonds and the energy absorbed or released is always _______
conserved
some chemical reactions absorb more energy than they ________
release
_____ reactions are chemical reaction that absorb thermal energy
endothermic
in these reactions _______ energy is required to break the bonds of the ______ than is released when products form
more, reactants
most chemical reactions release more energy than they ________
absorb
______ reactions are chemical reactions that release thermal energy
exothermic
in these reactions ______ energy is required to break the bonds of the ________ than is released when products form
less, reactants
some chemical reactions do not _______ by themselves
start
all reactions require ______ to start the breaking of ______
energy, bonds
_________ is the minimum amount of energy that is needed to start a chemical reaction
activation energy
the activation energy of some reaction is so _____ that enough energy to start the reaction comes from the ________
low, surroundings
the activation of some reactions is so ________ that more energy is needed to start the reaction
high
the rate of a reaction is the _____ at which it occurs
speed
chemical reactions occur ______ if the particles _______ more often or if the particles move _________ when they collide
faster, collide, faster
_________ area can affect the rate of a reaction
surface area
surface area is the amount of ______ outer area of a solid
exposed
_______ surface area increases the rate of reaction because more _______ on the surface of a solid come in contact with the _____ of another substance
increase, particles,particles
_______ can affect the rate of reaction because at higher _______ particles move faster
temperature, temperature
at higher temperatures particles _______ more often
collide
they also collide with more _____
energy
an increase in _______also increases reaction rate because there are more particles to ______ with each other
concentration, collide
for gases increased _______ pushes particles closer together and more _______ occur
pressure, collisions
a _____ increase reaction rate by lowering the ________ energy of a reaction
catalyst, activations
a catalyst is not itself permanently ______ during a chemical reaction
changed
catalysts also no not change the ________ or the products of the reaction
reactants
an ________ is a catalysts that speeds up chemical reactions in living cells
enzyme
substances called ______slow down or stop a chemical reaction
inhibitors
minimum amount of energy needed to start a chemical reaction
activation energy
substance that increases the reaction state by lowering the activation energy of a reaction
catalyst
chemical reactions that absorb thermal energy
endothermic
catalyst that speeds up chemical reactions in living cells
enzyme
chemical reactions that release thermal energy
exothermic
substance that slows down or even stops a chemical reaction
inhibitor