video 1

Question 1

how can reactions be classified?

Answer 1

based on whether they release or absorb energy

Question 2

what are reactions that absorb heat called?

Answer 2

endothermic

Question 3

what are reactions that release heat called?

Answer 3

exothermic

Question 4

what is the heat absorbed form/emitted to?

Answer 4

the suroundings

Question 5

what are we actually measuring the temperature of?

Answer 5

the water

Question 6

when we have an endothermic reaction, what is happening?

Answer 6

the surrounding temp decreases, heat is absorbed from surroundings

Question 7

when we have an exothermic reaction, what is happening?

Answer 7

the surrounding temp increases, heat is emitted to surroundings

Question 8

what is enthalpy?

Answer 8

energy that is stored in chemical bonds of substance

energy available in chemical that can be released as heat

Question 9

what is the symbol for enthalpy?

Answer 9

H

Question 10

what is enthalpy measured in?

Answer 10

kJ/mol

Question 11

why do we measure enthalpy change rather than actual quantity of H available

Answer 11

it is easier to measure how much it has increased or decreased by

Question 12

what is an energy level diagram?

Answer 12

a reaction profile

Question 13

what does an exothermic energy profile look like?

Answer 13

reactants are at the top, products are at the bottom

Question 14

what is activation energy?

Answer 14

the energy we need to put in to begin with, to make the products

Question 15

what does an endothermic energy profile look like?

Answer 15

reactants are at the bottom, products are at the top

Question 16

when will the enthalpy change be negative, when will it be positive?

Answer 16

exo - negative
endo - positive

Question 17

where is the activation energy represented on both energy profile graphs?

Answer 17

activation energy is always difference between reactants and top of the curve