U5|Thermochemistry 24-26 - section 5&18

Question 1

What is energy?

Answer 1

• is the capacity to do work or to produce heat
• can’t measure the absolute energies
• can only measure energy transferred (change ing energy deltaU or deltaE)
• units is Joules or kJ or calories Kcal

Question 2

What is work?

Answer 2

• energy transfer due to an applied force

Question 3

What is heat?

Answer 3

• energy transfer due to a difference in temperature
• HEAT IS NOT TEMPERATURE
• energy transfer due to anything other than work

Question 4

what is an extensive property?

Answer 4

• dependent on the amount of substance
• eg. mass, volume, heat, heat capacity

Question 5

what is an intensive property?

Answer 5

• does not depend on the amount of substance
• eg. density, melting point, temperature

Question 6

what does the quantity of heat depend on?

Answer 6

1. temperature change of the substance
2. amount of substance (usually mass)
3. nature of substance

Question 7

work done BY a gas

Answer 7

• w<0 (negative sign)
• expansion
• gas will expand, forcing the piston to perform work on its surroundings

Question 8

work done TO a gas