Which of the following is the correct definition for a catalyst?
A substance that increases the rate of a chemical reaction without being used up.
A substance that increases the rate of a chemical reaction but is used up.
A substance that decreases the rate of a chemical reaction without being used up.
Increasing the concentration of a reactant increases the rate of reaction because:
It gives the particles more energy.
It increases the number of collisions per unit time.
It lowers the activation energy barrier.
The rate of the reaction between calcium carbonate and hydrochloric acid cannot be studied by:
Recording the volume of carbon dioxide gas produced over a period of time.
Recording the change in mass of the reaction mixture over a period of time.
Recording the mass of solid precipitate formed over a period of time.
Which of the following is the correct explanation for why increasing the temperature of a reaction increases the rate of reaction?
The particles gain energy and there are more successful collisions per second.
The particles lose energy and there fewer successful collision per second.
The particles gain energy and there are fewer successful collisions per second.
The rate of a reaction is determined by which of the following?
time
\[ \frac {1}{time}\]
\[ \frac {1}{(time)^2}\]