Chapter 6

Question 1

Calculate Internal Energy Change

Answer 1

ΔE = q + w

If heat is negative/exothermic then so is work, and vice versa

Question 2

Calculate Heat Energy

Answer 2

Heat = Mass × Specific Heat × Temperature Change

q = m × Cₛ × ΔT

Question 3

Calculate Thermal Energy Transfer
Measuring ΔHrxn calorimetry at Constant Pressure

Answer 3

qhot = -qcold

m × Cₛ × ΔT = -(m × Cₛ × ΔT)

Question 4

Calculate Kinetic Energy

Answer 4

KE = (1/2)mv^2

Question 5

Exothermic

Endothermic

Answer 5

Exothermic: System releases heat into the surroundings
Surroundings gain heat, system loses heat
Negative

Endothermic: System absorbs heat from surroundings
Surroundings lose heat, system gains heat
Positive

Question 6

Enthalpy

Enthalpy Calculation

Answer 6

Enthalpy: The sum of the internal energy of the system and the product of pressure and volume

H = E + PV
ΔH = ΔE + P×ΔV

Question 7

Calculate Hmol

Answer 7

Hmol = qrxn/mol
qrxn = -qsol
-qsol = -(mass×C×ΔT)sol

Question 8

Redheffer machine and exposers

Answer 8

Redheffer’s perpetual motion machine was a fraud as Isiah Lukens showed that it was powered by a driveshaft

Redheffer’s other perpetual motion machine was exposed by Robert Fulton as it was cranked by a man in the back.

Question 9

Chemistry & Environment Reading

How to concentrate Solar nrg?

Solar nrg from chemical bonds?

Answer 9

How to concentrate solar nrg: Parabolic troughs, solar power towers, dish/engines

Sol nrg chemical bonds: in a fuel cell solar nrg causes water decomp. and then hydrogen recombines with oxy to make water and electricity is released