• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3
4. 4
4
5. 5
5
6. 6
6
7. 7
7
8. 8
8

# Enthalpy change

Extracts from this document...

Introduction

Investigation 19 MEASURING ENTHALPY CHANGES Method: Part A 1) Put 100 cm3 of water at about 60 �C into a polystyrene cup by mixing boiling water from the kettle with cold water from the tap. 2) Dry about 25 g of ice with a piece of paper towel and weight them both. 3) Rapidly record the temperature of the water and transfer the ice to it, then record the mass of the paper towel and the water it has absorbed. 4) Stir the water ice mixture and record the temperature of the water as soon as all the ice has just melted. Part B 1) Take the polystyrene cup and use measuring cylinder to put 50 cm3 of 1 M aqueous copper sulphate in it. 2) Weigh out accurately about 5 g of powdered zinc into a weighing bottle. 3) Stir and record the temperature of the copper sulphate at half minute intervals for 2 minutes and then add the powdered zinc. 4) Record the temperature at half minute intervals until the temperature has been falling for ten consecutive recordings. Part A: the heat required for a change of state Firstly, I needed to boil the water in the kettle, so that it can be used in the experiment. ...read more.

Middle

Also, I calculated how many moles of zinc I am going to add to the solution. MZn=65g 1 mole - 65 g x- 5 g x=0.077 moles of Zn Since I don't know, I decided to calculate how many moles of zinc are actually going to react with copper sulphate. The equation for the reaction looks as follow: CuSO4 (aq) + Zn (s) � ZnSO4 (aq) + Cu (s) or Cu2+(aq) + Zn (s) � Zn2+ (aq) + Cu(s) 1 mole - 250 g x- 12.5 g x=0.05 moles of CuSO4 As the proportion between Zn and CuSO4 is 1:1, 1 mole CuSO4 - 1 mole Zn 0.05 moles - x x=0.05 moles of Zn will actually react Which means that zinc is in excess. Next step was to record-firstly-the temperature of the solution, then add zinc. Table 2: The measurements of time for the second reaction. Time [�0.50 s] Temperature [�0.05�C] 0.00 19.00 30.00 18.90 60.00 18.80 90.00 18.80 120.00 18.80 150.00 42.70 180.00 64.40 210.00 67.60 240.00 66.40 270.00 64.80 300.00 63.80 330.00 63.10 360.00 62.20 390.00 61.40 420.00 60.40 450.00 59.50 480.00 58.70 510.00 58.00 540.00 57.20 570.00 56.40 600.00 55.60 630.00 54.90 660.00 54.20 690.00 53.40 720.00 52.80 Rounded to 2 decimal place First two minutes of the temperature was measured for the solution of CuSO4 only. ...read more.

Conclusion

error = error= error=1.38% This lead me to conclusion that the method of collecting data and the way I processed it was accurate and very satisfying. Extrapolations on the graph allowed me to use precise values of measured datas and therefore to calculate the enthalpy changes. Errors occured during the experiment and might have affected the final results: * wrong or error in calculations to create the solution * balance with only 2 decimal places * the uncertainity of cylinders * human reaction during measurements [0.15s] * adding powder in not exact time * polystyrene cup might not have been isolated all the time, so loss of energy could occur * some zinc powder stayed on the Vernier coach thermometer * the value of heat capacity differs; I assumed it was 4.18 g-1 K-1 To improve the experiment, I might make some changes: * make more readings to reduce the uncertainity * more stirring during the experiment, to make sure all substances dissolved * use very icy ice (taken straight from the fridge) so it wouldn't melt too soon * be more accurate while measuring- add all substances at the exact time * use more accurate balance and weigh all substances twice * use thermometer and Vernier coach to make sure that temperature recorded is the same as measured * have more time to do more measurements, prelong the time of measurements ?? ?? ?? ?? Gracja Kowalska kl. 2 IB 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Chemistry section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related International Baccalaureate Chemistry essays

1. ## Thermodynamics: Enthalpy of Neutralization and Calorimetry

�.5 C� 65.0 �.5 C� Final Temperature 39.3 �.5 C� 40.0 �.5 C� 42.2 �.5 C� Heat Capacity of Solution 2.598 �.00035 cal/gC� 1.661cal/gC� 1.166cal/gC� 1.808cal/gC� After looking at the charts I can see that there are large discrepancies between trials 1, 2, and 3 for the heat of Neutralization

2. ## Hesss Law Lab, use Hesss law to find the enthalpy change of combustion of ...

The molar enthalpies for both reactions were calculated. Both of these reactions were carried out three times each. The last intermediate reaction was not done because it was almost impossible to carry out that experiment by using the available equipments but instead table values were given for those reactions.

1. ## Measuring the Enthalpy Change for the reaction

powder to Copper Sulphate solution at the fourth minute, the temperature dramatically increase from 19.2�C to 40.2�C. The reaction is spontaneous as the temperature increase very rapidly and then gradually slowing down in the later time interval. From my graph, I have drawn the best fit line for the data

2. ## hess's law

Conclusion: After conducting the above mentioned experiment, observing the reactions and after carrying out all the appropriate and necessary calculations outlined in the previous pages, I hereby conclude that the molar enthalpy change for the chemical reaction between anhydrous copper (II)

1. ## Enthalpy Change of a Displacement Reaction

Absolute uncertainty=3.8kJ � 8%=�0.3kJ 2. The heat released by the warm water. a) The mass of warm water. m(water)=?(water)�V(water) =1g/mL�50mL =50g Absolute uncertainty=�1mL (Assume that the absolute uncertainty of ?(water) is negligible) % uncertainty=1/50 � 100%=2% b) The change of the temperature ?T is the temperature change after the warm water was added into the cold water.

2. ## Electrolysis of copper sulphate

Place the each electrode pair in a beaker filled with sulphuric acid prepared previously about 4 cm into the beaker and fix both electrode pairs to polar sides of the beaker by bending. This controls the surface area and the distance between the electrodes.

1. ## IA-Enthalpy Change of Reaction - Zinc and Copper Sulphate.

This is a source of uncertainty because the temperature probe had to be isolated from the solution when the lid was opened, causing a sharp plummet in the temperature graph. * Some of the materials used, such as the temperature probe and the Styrofoam cup, had to be shared with many other students and were not always cleaned well.

2. ## The aim of this experiment is to examine the enthalpy of combustion of the ...

28.0 60 35.0 34.0 34.5 34.5 75 43.0 42.0 41.0 42.0 90 48.0 47.5 46.0 47.5 105 50.0 49.0 49.0 49.0 120 53.0 52.5 51.0 52.5 135 59.5 59.0 56.5 58.0 150 58.0 58.5 56.0 57.5 165 57.5 58.0 55.5 57.0 180 57.0 57.5 55.0 56.5 210 56.5 57.0 55.0

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to
improve your own work