R: Energetics

Question 1

what is a reaction that gives out heat called

Answer 1

exothermic, exo means exit

Question 2

what is a reaction that absorbs heat called

Answer 2

endothermic reaction

Question 3

what can you tell about the products of exo and endothermic reactions (2)

Answer 3

exothermic - less energy in the product so they are more stable, cold
endothermic - more energy in the product than reactants so they are less stable, hotter product

Question 4

what is enthalpy change (3)

Answer 4

the amount of heat given in or out in a chemical reaction, its symbol is a triangle and a H (△H) and its units are kj/mol, kilojoules per mole

Question 5

what is the difference between △H- and △H+
in a chemical reactio

Answer 5

△H- is exothermic because the substance has lost heat energy so its - heat
△H+ is endothermic because the substance has gained heat energy by abosrbing so its + heat

Question 6

what is Q=mc△T

Answer 6

its the equation for calculating energy loss or gains in a chemical reaction
Q= energy
m = mass
c = specific heat capacity J/g/C°
△T = temperature change

Question 7

what is specific heat capacity

Answer 7

different substances absorb heat at different rates, SHC is how much heat must be put into something for the temperature to rise

Question 8

what is specific heat capacity’s unit

Answer 8

the amount of heat needed to raise 1 gram of substance by 1 degree, its measured in Joules/g/C

Question 9

how do you do the spirit burner experiment for calorimetry

Answer 9

1. Measure 100g of water and
   transfer to a copper can
2. record the initial
   temperature
3. Weigh a spirit burner
   containing ethanol.
4. using the spirit burner, heat
   the water until there is a 40oC
   increase in temperature.
   5 weigh the spirit burner to
   determine mass used in reaction.