Experiement A: Calorimetry

Question 1

Objectives (2)

Answer 1

Determine the heat capacity of a metal object and a liquid (2-PrOH)

Determine the enthalpy of fusion of ice

Question 2

What is an intensive property

Answer 2

Doesn’t depend on the mass of the substance or system

Question 3

What is an extensive property

Answer 3

Does depend on the mass of the substance or system

Question 4

Is heat capacity extensive or intensive

Answer 4

Extensive

Question 5

What is heat capacity, measured in, and variable

Answer 5

Amount of energy needed to chance an objects temp by one degree

J/Celsius

Question 6

A system contains ____ ____energy (not heat or work)

Answer 6

Internal energy

Question 7

In calorimetry energy is transferred due to a ___ change

Answer 7

Temp

Question 8

What is heat and what variable represents it

Answer 8

Energy in transition

q

Question 9

What formula for C relates heat and temp

Answer 9

C = q/(Tf-Ti)

Question 10

What formula for C relates specific heat capacity to mass of a substance

And when do you use this

Answer 10

C = c(mass of substance)

When substance is known

Question 11

Are specific heat capacity and mass extensive or intensive

Answer 11

Intensive

Question 12

What is specific heat capacity measured in

Answer 12

c

Question 13

What formula relates molar heat capacity to moles of substance

And when do you use this

Answer 13

C = Cm(moles of substance)

Question 14

What is Cm

Answer 14

Molar heat capacity

Question 15

Are Cm and moles extensive or intensive properties

Answer 15

Intensive

Question 16

Is the calorimeter is at constant pressure and why

Answer 16

Yes

It’s open to the atmosphere

Question 17

What is the definition of triangle H, what does it represent, units

Answer 17

Energy transferred that entrees or leaves the system

Enthalpy change

J/mol

Question 18

What does endothermic mean

Answer 18

Energy transferred to the system from surroundings

Question 19

(+) triangle H

(-) triangle H

Endo or exo for each?

Answer 19

(+) endothermic

(-) exothermic

Question 20

How are enthalpy change and temp related

Answer 20

Triangle H = heat (at constant pressure)

Question 21

How does heat capacity relate enthalpy change and temp

Answer 21

C = triangle H/ (Tf-Ti)

Question 22

During the experiment why does the total enthalpy change = 0

Answer 22

(Total enthalpy of calorimeter)
+ (it’s contents) = 0

Question 23

Part 1: heat capacity

Explain the three steps

Answer 23

1) calorimeter holds room temp water

2) metal block will be heated in a boiling water bath

3) when metal block is transferred to calorimeter, block will LOSE heat to water and calorimeter, temp of calorimeter water increases

Question 24

How does total enthalpy change relate enthalpy change of the block and enthalpy change of the water

Answer 24

Triangle H total = triangle H block
+ triangle H water = 0

So,

Triangle H block = -(triangle H water)

Question 25

How does the heat capacity of the block relate the heat capacity of water, and the temp of water and the block

Answer 25

C block = (-C water(Tf-Ti)water)/
(Tf-Ti) block

Question 26

Formula for heat capacity of water

Answer 26

(Mass of water)(c)

Question 27

Formula for mass of water

Answer 27

(Volume added)(density of water at room temp)

Question 28

How does specific heat capacity of the block relate the heat capacity of the block and the mass of the block

Answer 28

c block = C block/ mass of block

Question 29

Part 2: enthalpy fusion of ice

Explain the objective and the one step

Answer 29

Estimate the enthalpy fusion of ice for H20(s) —-> H2O(l)

Ice at 0 degrees (melting point of ice) is added to calorimeter water at room temp, ice melts, water cools to Tf, water from melted ice warms from 0 degrees to Tf

Question 30

What does fusion mean

Answer 30

Melting

Question 31

How does triangle H water relate triangle H fusion and triangle H ice water

Answer 31

-triangle H water = triangle fusion + triangle H ice water

Question 32

How is the calorimeter built

Answer 32

• 2 polystyrene cups one side the other
• insert thermometer through the smaller of the two holes at the top

-black plastic sleeve on top holds tip of thermometer approx 1 cm away from bottom when lid is put into cups

Question 33

The measured max temp of calorimeter is less than ___
Because some energy enters/leaves calorimeter during reactions

Answer 33

Ideal

Question 34

After max temp is reached, temp will change back with time towards ___

Answer 34

Ti