chemstry chapter 8

Question 1

what is an exothermic reaction

Answer 1

an exothermic reaction is a reaction that grants thermal energy to the surroundings leading to an increase in the temperature of the surrounding

Question 2

what are the characteristics of an exothermic reaction

Answer 2

• thermal energy is given out from the reactants and transferred tot he surroundings
• the temperature of the reaction mixture rises

Question 3

what are some examples of physical process of an exothermic reaction

Answer 3

• condensation
• freezing
• dissolving of anhydrous salts

Question 4

what are some examples of chemical reaction of exothermic reactions

Answer 4

• combustion of fuels
• respiration
• corrosion of metals

Question 5

what is an endothermic reaction

Answer 5

an endothermic reaction is a reaction that takes in thermal energy from the surroundings leading to a decrease in the temperature of the surroundings

Question 6

what are the characteristic of an endothermic reaction

Answer 6

• thermal energy is absorbed and transferred from the surroundings to the reactants
• the temperature of the reaction falls

Question 7

what are some examples of the physical process of an endothermic reaction

Answer 7

• evaporation
• boiling
• melting

Question 8

what are some examples of chemical reaction of an endothermic reaction

Answer 8

• photosynthesis
• thermal decomposition

Question 9

what does the enthralpy change or the symbol H represent

Answer 9

represents the difference in energy content of the reactants and products

Question 10

how can we calculate the enthalpy change

Answer 10

enthalpy change, H = total energy of products - total energy of reactants

Question 11

what does the pathway diagram for an exothermic reaction show

Answer 11

• total energy of the product is less than that of reactants
• difference between total energy content of the products and that of the reactants is equal to the amount of energy given out during the reaction

Question 12

what does the pathway diagram for an endothermic reaction show

Answer 12

• total energy of the products is more than that of reactants
• difference between the total energy content of the products and that of the reactants is equal to the amount of energy absorbed during a reaction

Question 13

what is the activation energy

Answer 13

activation energy, E is the minimum energy that colliding particles must have to react

Question 14

what causes energy changes in a chemical reaction

Answer 14

• the break of bonds of an endothermic reactions
• making bonds of an exothermic reaction