energetics

Question 1

exothermic

Answer 1

reaction releases energy to surroundings
temp. increasese
bonds in products are stronger/ more than in reactants

Question 2

endothermic

Answer 2

reaction absorbs energy from surroundings
temp. decreases
bonds in reactants are stonger/ more than in the products

Question 3

what is enthalpy

Answer 3

during a reaction the energy change is caused by the breaking and making of chemical bonds. this quantity of energy is called enthalpy (H)

Question 4

measuring ∆H

Answer 4

q=mc∆T
q= energy
m= mass of substance being heated
c= 4.18
∆T= temp change

Question 5

method to measure ∆H of dissolving

Answer 5

1. use a calorimeter because its an insulator
2. put calorimeter in beaker to make it more stable
3. pour in the solvent
4. measure temp.
5. pour in solute and measure the max/min temperature
6. calculate the ∆H

Question 6

bond enthalpy

Answer 6

the energy stored in bonds that represents the energy needed to break 1 mol of a specific bond

Question 7

is bond making endo or exothermic

Answer 7

exothermic and releases the same value of energy

Question 8

what is ∆Hn

Answer 8

its the enthalpy change when an acid plus base produce 1 mol of water

Question 9

enthalpy of combustion calculation

Answer 9

q=mc∆T
m is only the mass of water
the mass of the substance is used later for calculating the number of mols