Chem Flashcards
(29 cards)
The speed of chemical reactions can vary from very fast to extremely ____
Slow
is a measure of how much something changes within a specified amount of time.
rate
In chemistry, the rate of a chemical reaction, or the reaction rate, is usually expressed as the change in the amount of reactant or _____
product per unit time.
A model called _____ ____ is used to relate the properties of particles to the rates of chemical reactions.
collision theory
According to c_____ t_____, atoms, ions, and molecules can react to form products when they collide if the particles have enough kinetic energy
collision theory
Particles that do not have enough energy to react bounce apart unchanged when they c____.
collide
effective collision of oxygen and hydrogen molecules produces _______
water molecules.
An ineffective collision of oxygen and hydrogen molecules produces _______; the reactants bounce apart unchanged.
no reaction;
minimum energy that colliding particles must have in order to react is called the A _____ E ____
activation energy.
When two reactant particles collide, they may form an
activated complex.
is an unstable arrangement of atoms that forms for a moment at the peak of the activation-energy barrier.
activated complex
forms only if the colliding particles have enough energy and if the atoms are oriented properly.
activated complex
explains why some reactions are extremely slow at room temperature.
Collision theory
Usually, raising the _______ speeds up a reaction.
Lowering the _______ usually slows down a reaction.
temperature
At higher ______, particles move faster.
The _________ increases along with the percentage of particles that have enough kinetic energy to slip over the activation-energy barrier
frequency of collisions
The number of particles in a given volume affects the rate at which reactions occur.
Concentration
The total surface area of a solid or liquid reactant affects the rate of a reaction.
Particle Size
The ______the particle size, the greater the surface area is for a given mass of particles.
smaller
The result of an _____ in surface area is an increase in the frequency of collisions and the reaction rate.
increase
Another way to increase the surface area of solids is to _____ them.
dissolve
You can also increase the surface area of a solid by _____ it into a fine powder.
grinding
destroyed this sugar refinery.
explosion
Increasing the temperature is not always the best way to increase the rate of a reaction. A _____ is often better.
Catalysts
