rates of reactions

Question 1

exothermic reactions

Answer 1

A reaction that releases energy through light or heat. It gives net energy to its surroundings. The energy needed to initiate the reaction is less than the energy released.

Question 2

endothermic reactions

Answer 2

A reaction that absorbs or takes in energy in the form of heat, resulting in a net decrease in temperature. It stores the energy in the bonds formed in the reaction.

Question 3

precipitation

Answer 3

An insoluble solid that emerges from a liquid solution. It forms either by reacting two salts or by changing the temperature to affect the solubility of the compound.

Question 4

compounds

Answer 4

A substance formed when two or more chemical elements are chemically bonded together.

Question 5

mixtures

Answer 5

a material made up of two or more different substances which are mixed

Question 6

solvent

Answer 6

the liquid in which a substance dissolves

Question 7

solute

Answer 7

the substance that dissolves in a liquid (solvent)

Question 8

dilute solution

Answer 8

A solution that contains more solvent than solute.

Question 9

solution

Answer 9

a homogeneous mixture of two or more substances

Question 10

concentrated solution

Answer 10

A solution which contains a large amount of solute relative to the amount that could dissolve.

Question 11

Saturated Solution

Answer 11

A solution in which there is no more solute that can be dissolved in the solvent.

Question 12

what is the most common solvent

Answer 12

water

Question 13

a substance that speeds up a chemical reaction but it is not consumed or used by the reaction

Answer 13

catalyst

Question 14

What are the factors that affect the rate(s) of reaction?

Answer 14

Particle Size, Temperature, Concentration, Catalysts.

Question 15

Biological catalysts: proteins that speed up the rate(s) of chemical (biochemical) reactions in living organisms.

Answer 15

enzymes

Question 16

Decreasing __________ speeds up chemical reactions.

Answer 16

particle size

Question 17

Increasing ___________ speeds up chemical reactions.

Answer 17

Temperature and/or Concentration.

Question 18

What do you need to know and remember about catalysts?

Answer 18

1. Catalysts speed up some reactions.
2. Catalysts are not used up during reactions.
3. Catalysts can be recovered and used again at the end of reactions.
4. Catalysts in living things (biological catalysts) are called enzymes.
5. Catalysts in the same state as the reactants are called homogeneous.
6. Catalysts in a different state from the reactants are called heterogeneous.

Question 19

How can the average rate of reaction be calculated?

Answer 19

1. The average rate of a reaction can be calculated from initial and final quantities and the time interval.
2. The average rate at any stage of a reaction can be calculated from change in quantities and the time interval.

Question 20

How can the rate of a reaction be shown to decrease over time?

Answer 20

By calculating the average rate at different stages of the reaction.

Question 21

What is surface area?

Answer 21

The face or area that undergoes the chemical reaction.