Rates of reaction

Question 1

Exothermic Reaction

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 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 temperture. iT stores the energy in the bonds formed in the reaction.

Question 3

Reactants

Answer 3

substances that are involved in a chemical reaction and that are changed by it

Question 4

Products

Answer 4

The substances that are produced by a chemical reaction

Question 5

Four indicators that show a chemical reaction has taken place

Answer 5

Colour change, Effervescence, Precipitation and Energy (temperature) change

Question 6

Colour change

Answer 6

when two substances react or also when a compound is broken down by heating it (thermal decomposition)

Question 7

Effervescence

Answer 7

some chemical reaction result in a product that is different state to the reactions

Question 8

Precipitation

Answer 8

Liquid react together to produce an insouble solid

Question 9

Energy change

Answer 9

during the reaction, bonds inside the substances that are reacting together must be broken and new chemical bonds must be formed in the products that are being made.

Question 10

for a reaction to occur -

Answer 10

the particles that are reacting must collide with each other

Question 11

Collisions

Answer 11

some the collisions that take place cause a chemical change (successful collisions). The greater, the number of successful collisions the faster the rate of reaction (collision theory)

Question 12

Temperature (factor affecting rates)

Answer 12

if the temp is increased , the particles have more energy and so move quicker. Increasing that temp increases the rate of reaction because are often and with more energy

Question 13

Concentration (factor affecting rates)

Answer 13

if concentration of reactants is increases, there are more reactants particles moving together. There will be more collisions and so the reaction rate is increased

Question 14

Particle Size (factor affecting rates)

Answer 14

by decreasing the particle size of a reactant, we are increasing its surface area. the greater the surface area, the higher the chance of collisions. smaller particles= faster reaction

Question 15

use of catalyst (factor affecting rates)

Answer 15

catalysts increases the rate of reaction but it is not used up in the reaction. if a catalysts is present, the reacting particles can collide more successfully with less energy

Question 16

monitoring the rate of reaction

Answer 16

measured on how fast the reactants are being used up and how fast the products are being made up

Question 16

the rate can be determined by measuring

Answer 16

Changes in the concentration of the reactants or products .
Changes in the mass of the reactants or products
Changes in the volume of the reactant or products

Question 16

Calculating the rates of reactions

Answer 16

using results of experiments, the average rate of reaction can be calculate.
Average rate= change in measurble quantity/ change in time