Kinetics

MUFP Chemistry

Lab Assessment 2

2018-2019

Name
CEG number	080
Signature

Time allowed: Up to 1 hour and 30 minutes (practical only)

Instructions

1. Listen carefully to instructions from the staff members and you must stop immediately if asked to do so.

2. You must work safely at all the times and wear appropriate clothing.

3. If you need help or any additional equipment raise your hand up.

4. Scientific Calculators are allowed.

5. Before you do your practical your teacher will explain what you are going to do and might carry out a demo- you are advised to listen carefully and take notes.

Information to candidates

1. Before you go to the lab, you must have read the risk assessment attached together with this lab report template.

2. Only use this template to prepare for your lab-report which must be done electronically in Word and submitted on Turnitin by Wednesday, 1 May 2019.

3. You must submit your signed paper copy to your tutor in class on Thursday, 2 May 2019.

4. Graphs or diagrams can be done by hand and then scanned for submission.

5. A coursework submission form must be included with the lab report.

6. If you fail to meet the deadline, your work will be treated as a late submission and the result will be capped at 40%.

Total marks for this paper: 35

Marking Criteria (This is a simplified version of the rubric calculator)

Quantitative Practical Task – 35 Marks

	Planning (P)	Total	13
P1	Introduction (include hypothesis)	1
P2	Variables	3
P3	Materials/Apparatus	1
P4	Safety Precautions	1
P4	Apparatus Diagram	2
P5	Method	5
	Obtaining and Processing Evidence (O)	Total	12
O1	Safety Precautions- protective clothing, disposal of materials, handling of spillages, general safety awareness.	2
O2	Techniques- effective use of a given quantitative procedure	3
O3	Results- show results correctly on the results table	1
O4	Processing Results- Draw a table to show loss in mass (g) at each time interval. Use the data on the table to construct appropriate graph(s) to compare the effect of concentration on the rate of reaction. If appropriate, include a suitable method to deduce the order of reaction with respect to the hydrochloric acid.	6
	Discussion and Evaluation (E)	Total	10
E1	Simply state results	1
E2	Use of scientific knowledge to explain results	4
E3	Comment on anomalies	1
E4	Comment on the reliability of the method	1
E5	Conclusion(s)	2
E6	Recommendations on further work	1

Quantitative Analysis- Physical Chemistry

Aim: to investigate the effect of increasing the concentration of hydrochloric acid in the reaction between hydrochloric acid and marble chips.

Introduction :

Marble is a metamorphic rock composed of calcium carbonate. Hydrochloric acid reacts with calcium carbonate to form calcium chloride, water and carbon dioxide.

The rate at which carbon dioxide is produced provides a method of measuring the rate of reaction. The most convenient way of doing this is by following the loss in mass as the gas is evolved, because carbon dioxide is sufficiently dense to cause measurable decreases in mass using a standard laboratory balance

Prediction:

Variables:

Independent Variable (main controlled variable-input)	Dependent Variable (responding variable-output)
Other controlled variables: (variables that should be kept constant to achieve a fair experiment/test)

Materials: (You are advised to make appropriate annotations for clarity before/during the practical and then to rewrite this explicitly. )

Hydrochloric acid (2M)	Marble chips
2 Measuring cylinders	Conical flasks
Top-pan balance capable of weighing to three decimal places	Stop watch
Spatulas	Eye protection
Weighing boats	Distilled water

Safety Precautions: (Give at least three lab specific and two general safety precautions appropriate with reasons)

SAFETY PRECAUTION	REASON(S)
1.
2.
3.
4.
5.

Apparatus Diagram(s): (*Draw a well labelled, simple apparatus diagram. You can also use suitable information technology programmes. Any apparatus diagrams taken from the internet should be cited appropriately).

Instructions: (You are advised to make appropriate annotations during the practical and then to rewrite this using the right format and reflecting on how you did the practical for your method. )

1. Weigh out 2.5g of marble chips onto a weighing boat.

2. Using the measuring cylinder, transfer 25cm3 of hydrochloric acid to a conical flask and loosely plug the neck of the flask with cotton wool (Prepare the acid solutions as shown by the table at the top of the next page).

3. Weigh the conical flask containing the acid.

4. Remove the cotton wool-plug and immediately add the marble chips to the acid and start the stopwatch and place back the cotton wool-plug. Gently agitate the conical flask as the reaction takes place.

5. Record the mass every 30s for 5 minutes (10 readings). The starting mass will be the mass of the conical flask + acid + 2.5g of marble chips.

6. Using your processed data, plot appropriate graph(s). Deduce the rates of the reactions at different concentrations and if possible, find the order of reaction with respect to hydrochloric acid.

Molar concentration	V of acid (cm3)	V of water (cm3)
0.4	5	20
0.8	10	15
1.2	15	10
1.6	20	5
2.0	25	0

Results Table:

	Mass (g) at different concentrations (mol.dm-3)
Time(s)	0.4	0.8	1.2	1.6	2.0
0
30
60
90
120
150
180
210
240
270
300
Total loss (g)

Processing results:

*For your graph(s) you will need to show loss in mass for each time interval, so you are advised to draw another table before you do your graph(s).

How to work out loss in mass

Loss in mass = mass at 0s – mass at any time

END OF EXAM PAPER