Socrates - Comenius 1: 
School Project “We are all living under the same sky”


Physics

LABORATORY WORK No 3

Topic:

Determination of the heat received by a liquid body and delivered by a solid body during the heat exchange.


Name:

Jakub Prasek

Class:  

V3.A

Date:

13 December 2001

Cooperation:

Radek Chatrny, Jiri Beranek


Tasks:

1.

Determine the heat received by water and delivered by an iron roller during the heat exchange in calorimeter.

2.

Determine the change in internal energy of water and iron roller. Are these changes same or different?

3.

Answer the questions stated in the supplementary task.


Aids:

laboratory scales, set of weights, aluminium calorimeter, thermometer, beaker, water, iron roller, warming appliance


Theory:

In calorimeter, there is water weighing m1 and having temperature t1; the iron body weighs m2 and its temperature is t2; t2 > t1. We dip the body into the water in calorimeter and, after the heat exchange, we measure the temperatures t of water and body. We find out that t< t < t2. Water weighing m1 received the heat Q1 = c 1.m1.(t – t1); the iron body having been dipped into the water delivered the heat Q2 = c2.m2.(t2 – t); c1 is the specific heat capacity of water, c2  is the specific heat capacity of iron. The heat exchange is supposed to have taken place only between water having temperature t1 and iron body having temperature t2; then Q1 = Q2.


Solution:

Task No 1:

Progress:

 

a.

We drew the picture of calorimeter and described it.

b.

We described the mercury thermometer.

c.

First of all, we determined the mass m1 of the inner calorimeter vessel, then the mass mh of water, that we afterwards poured into the calorimeter and weighed again.

d.

We determined the mass m2 of iron roller.

e.

We mixed the water in calorimeter and after a while we determined the temperature t1 of  the mixed water.

f.

We poured the iron roller into the water and warmed it up, then we measured the temperature t2 of water bath.

g.

Immediately we moved the roller into the water in calorimeter, mixed it and afterwards we measured the highest temperature t.

h.

From the acquired dates, we reckoned the heat Q1 received by the water in calorimeter and the heat Q2 delivered by the iron roller.

Picture:


Photo

Photo

Photo

The parts of mixing calorimeter

(1) inner vessel with cross-shaped mat, (2) outer vessel, (3) inner cover, (4) outer cover, (5) stirrer, (6) thermometer

The parts of mixing calorimeter


Thermometer:

measuring range of the scale: from 10 oC to 100 oC

the least division of the scale: 0.5 oC

measuring tolerance: 0.25 oC

Mass measurement:  

m1 = 174 g (measuring tolerance 100 mg)

m2 = 123 g (measuring tolerance 100 mg)

Temperature measurement:

t1 = 23 oC

t2 = 80 oC

t = 26 oC

Temperature difference:

t  t1 = oC

t2  t = 54 oC

Estimate of temperature difference measuring tolerance: 0.5 oC

Heat received by water: Q= c1.m1.(t – t1)

Calculation and rounding: Q= 4.18 . 0.174 . 3 kJ = 2.18 kJ

Heat delivered by the steel body: Q2 = c2.m2.(t2  t)

Calculation and rounding: Q2 = 0.450 . 0.123 . 54 kJ = 3 kJ

Comparison of heat values: Q1 < Q2

Comparison of internal energy of water inside the beaker (Q1) and of the steel body (Q2): Q< Q2


Task No 2:

After  the water had been heated, its inner energy rose by Q2. After the metal roller had been heated, also its inner energy rose but when it was transferred into the water in calorimeter, its inner energy sank by Q2. That is why Q< Q2. Obviously the heat exchange was realized not only with the water in calorimeter.


Task No 3:

a.

Why do you fasten the thermometer so as just to dip the vessel with mercury into the water before measuring the water temperature? I fasten the thermometer this way in order to stabilize the mercury in thermometer on the current temperature and to ensure the thermometer not to touch the vessel side.

b.

Why do you have to mix the water with a stick before measuring the temperature? I have to mix the water so that the water temperature is the same in all parts of the vessel.

c.

Why is temperature t2 the temperature of water in the second beaker and, at the same time, the temperature of the steel body? It is identical as they both were heated to the same temperature, the balance of heat has been established.

d.

Why do you have to put out the burner before measuring the temperature t2? I have to put out the burner so as not to rise the temperature any more.

e.

Between which bodies the heat exchange could have happened, except for heat exchange between water having temperature t1 and steel body having temperature t2? For example between the water and the vessel, between the water and the thermometer, between the water and the stick. 


Conclusion:

The heat received by water is 2.18 kJ and the heat delivered by metal roller is 3 kJ. The heat Q1 is smaller than Q2 and the change in the inner energy of water is smaller than the change in the inner energy of the body. The heat escaped while transferring the roller into the calorimeter. We fulfilled all the set tasks and I regard this laboratory work as successful. We are looking forward to the next laboratory work during which we undoubtedly learn a lot of new interesting information and knowledge. And what about you, dear project partners? How did you like this laboratory work?