Activity 1

What is the effect of temperature rise on reaction rate?

• It increases molecular concentration and slows reaction rate.

• It increases the number of effective collisions among reactants, thus increasing the reaction rate.

• It decreases the system's energy and limits how much further reaction can take place.

• It decreases the number of collisions and the energy of molecules to limit the further reaction.

Crushing a solid into a powder will increase the reaction rate. Why?

• The particles will collide with more energy.

• The powdered form has more surface area.

• The activation energy barrier will be lowered.

• The orientation of colliding particles will be improved.

Why does increasing the temperature of the reactants increase the reaction rate?

• Heat energy increases the size of the molecules of reactants, and therefore the molecules react more frequently.

• Heat energy helps to lower the amount of overall energy that is required for the reaction to occur.

• Heat energy causes some of the reactants to evaporate, thereby increasing the concentration of the reactants.

• Heat energy causes the particles of the reactants to move faster, therefore, react with each other more frequently.

Which of the following will decrease the number of effective collisions during a chemical reaction?

• Adding a catalyst.      

• Decreasing the temperature.

• Increasing the surface area.

• Increasing reactant concentrations.

Why are many types of foods stored in refrigerators?

• At lower temperatures, the chemical reactions that spoil food occur slower than usual.

• Refrigerators also contain enzymes that slow the rate of reactions that spoil the food.

• The volume inside the refrigerator decreases the concentration of the food particles, allowing them to decompose more slowly.

• Bacteria do not grow well in dark places.

A temperature increase causes the particles ......

• to slow down

• move faster

• collide higher

• in the right order

How does a catalyst work in speeding up a reaction?

• By lowering the activation energy or reaction

• by giving them more energy

• by making them more available

Why does a higher concentration increase the rate of reaction?

• it increases the amount of reactants

• it lowers the activation energy

• it increases the energy of particle collisions

• it increases the frequency of particle collisions

What is the rate of reaction?

• How fast a reaction is 
• How big a reaction is
• How loud a reaction is
• How much gas a reaction produces

Grinding a seltzer tablet into powder increases the rate of reaction due to increased

• concentration
• surface area
• temperature
• reactants