chapter 9-Enthalpy

Question 1

what is enthalpy

Answer 1

is a measure of the heat energy stored in a chemical system

Question 2

what happens to the products in an exothermic reaction

Answer 2

they have less enthalpy then the reactants
chemical energy is changed into thermal energy
chemicals lose energy
the energy that is lost by chemicals is gained by the surroundings which increases temp

Question 3

are exothermic reactions positive or negative

Answer 3

negative

Question 4

what happens to the products in an endothermic reaction

Answer 4

the products have more enthalpy then reactants
thermal energy is changed into chemical energy
chemicals gain energy
energy that is gained by the chemicals is lost by surrounding resulting in temp decrease

Question 5

are endothermic reactions positive or negative

Answer 5

positive

Question 6

what does enthalpy change depend on

Answer 6

temperature and pressure

Question 7

what are the standard conditions

Answer 7

pressure=100kpa
temp= 298k(25.c)
conc=1.00 mol dm-3