KKEK ChemEcar competition

Mg-Cu Driving Mechanism with Mg-HCl Stopping

Mechanism in ChemEcar Competition

Heng Joe Shen

Department of Chemical Engineering, Faculty of Engineering,

University of Malaya, 50603 Kuala Lumpur, Malaysia

Abstract

Chem-E-car competition challenges student teams from institutions of higher learning locally and

abroad to create and construct a shoebox-sized car powered by a chemical reaction or fuel cell. This event is

organized by the Institution of Engineers of Malaysia (IEM) and hosted by different university annually. The

car must be able to carry a certain load of water and stop within 2 minutes at a specified distance. The

competition comprises of 2 sessions (poser presentation and model car competition) and the winners are the

teams that ended nearest to the designated line.

In this article, one of the possible driving and stopping mechanism is being tested and run for few

times. The chosen driving mechanism is a voltaic cell comprises of magnesium stripe in magnesium

sulphate solution (MgSO4), copper rod in copper sulphate solution (CuSO4), connected externally through

copper wire and whisking tube acts as the porous pot. The highest voltage achieved is 12 V with

electromotive force of +2.71V. The chosen stopping mechanism is corrosion of magnesium stripe by

hydrochloric acid that breaks the circuit. By varying the concentration of hydrochloric acid, the model car

managed to reach different designated distance. Assuming the power of the voltaic cell remains constant,

multiple calibration graphs are plotted.

Keywords: ChemEcar, magnesium-copper cell, hydrochloric acid, model car.

1. INTRODUCTION

Rules

Eligibility : All undergraduates (public and private universities) including diploma students but

no inter-varsity team is allowed.

Model car : Must fit into 40 cm x 30 cm x 18 cm shoe box.

Load container : Must be able to carry 500mL of water

Distance and load : Between 15-25m +0.005m and 0-500mL of distil water

Scores : Distance from ending line for within bound and distance plus 3.00m for out of

bound. Will be disqualified for more than 30.00m from starting line.

Time allocation : Introduce their entry to audience (university name and briefly mention the

propulsion system) and 1 minute to reach the ending line. Must be ready 5 minutes

before the round started.

No. of

opportunities

: 2 opportunities to complete the course in 2 different rounds. Each round will have

different distance and load being set.

Winner : Team with lowest score and required 70% in the poster presentation.

For special prize, the winner will be the one with lowest average error.

PPE : Must wear lab coat, shoes, safety goggles and other required items.

MSDS : All MSDS of chemicals must be prepared.

Prohibition

Model car : No remote control or mechanical starting

Stopping

mechanism

: No mechanical force including stop switch using liquid draining out of a vessel.

Only chemical reactions such as colour changes are allowed.

Power source : No leakage, flame/any smoke and pressurized container,

Chemicals : No corrosive/hazardous chemicals and no open/improperly secured containers. All

chemical waste must be disposed accordingly.

Complaint : Deposit of RM200 within 1 hour of the incident.

Prizes

Model car : 1st RM3000 + certificate + trophy

2nd

RM2000 + certificate

3rd

RM1000 + certificate

Poster presentation : 1st RM500 + certificate

2nd

RM300 + certificate

3rd

RM200 + certificate

Special award : RM500 + certificate

Poster presentation will be evaluated according to 5 different categories: Description of chemical reaction,

design creativity/unique features, environmental/safety, economic aspect and quality of presentation.

2. LITERATURE REVIEW

List of possible combination for a model car is studied thoroughly.

Model car : Voltage varied from 6-12 V at different sizes and different tyre size

Motor : Run on DC current

Driving

mechanism

: Only primary battery cell is studies in details here [1]

.

i. Voltaic cell of copper and magnesium. Theoretical EMF achieved is +2.71V.

ii. Zinc air battery [2]. The cell is made of zinc sheet as negative terminal and stainless steel

(scour pad) as conducting agent between sodium hydroxide solutions with oxygen in

the air. Theoretical voltaic cell achieved is 0.87V

iii. Daniel cell. Theoretical EMF achieved is +1.10V.

iv. Lemon battery. Theoretical voltage achieved is 1.6V.

Stopping

mechanism

i. Reaction between magnesium stripes with hydrochloric acid. The magnesium stripe

corrodes and eventually breaks the circuit.

ii. Reaction between hydrogen peroxide with liquidfied beef [3]. The oxygen gas formed

will expand the syringe that eventually pushes the off button at the circuit.

iii. Iodine clock reaction. Iodine turns from yellow to dark purple in presence of starch that

eventually blocks the LED light from reaching the light dependent resistor (LDR) [4]

.

3. EXPERIMENTAL METHODS

Driving mechanism

7 copper rods were being polished with sand paper and inserted into whisking tube with one end being tied.

Magnesium stripes were cut in a spiral shape. Both of them were then inserted into the voltaic cell carrier

where the copper stood in the middle of each tube and magnesium stripe curled around it. Copper sulphate

solution was injected into each copper rod while magnesium sulphate was injected into outside of the

whisking tube. 2 crocodile clips were tied to both end of a copper wire and 8-10 of these were prepared.

These wires were then connected from copper rod in one cell to magnesium stripe in another cell. They were

arranged in such that it forms 4-3 cells in parallel to one another.

Stopping mechanism

Approximate 10 cm of magnesium stripe was cut and put into a small sample bottle. 10.0 M hydrochloric

acid was diluted to 5.0 M in 200 mL storage bottles. The acid was diluted to the required amount according

the competition in a 10 mL measuring cylinder.

Figure 1: Actual model car.

Figure 2: 2D diagram showing the completed model car with Mg-Cu

driving mechanism and Mg-HCl stopping mechanism

4. RESULTS

Customized check-list prior to the competition is prepared.

Item Brought? Item Brought?

1 Model car 13 Magnesium coil

2 Copper wire with clips 14 Magnesium stripe (stopping)

3 Voltaic cell holder 15 16 Copper rods

4 500 ml water bottle 16 Whisking tube (16 ready)

5 Scissors 17 2L MgSO4 solution

6 2 big beakers 18 2L CuSO4 solution

7 12 sample bottles with Mg 19 500 ml HCl solution

8 2 small beaker 20 Distil water

9 10 ml measuring cylinder 21 2 Syringes

10 1000 ml measuring cylinder 22 3 Cellophane tapes

11 Filter funnel 23 Sand paper

12 6 dry cells 24 Glu

6 Mg-Cu cells are arranged in different order to study the variation in voltage and current such that optimum

power is obtained.

Table 1: Voltage obtained at different arrangement of voltaic cells.

Arrangement Voltage (V) Resistance () Current (A)

1 cell 1.2 12 0.10

2 in series 3.2 32 0.10

3 in series 4.9 57.6 0.85

4 in series 5.0 66.7 0.75

6 in series 10.2 102 0.10

3-3 in parallel 5.1 25.5 0.20

2-2-2 in parallel 3.4 11.3 0.30

Concentration of power source: 200g/500ml of MgSO4 and 200g/500ml of CuSO4

First run: 206 mL of water for 17.25 m Second run: 480 mL of water for 15.45 m

Concentration (mol/dm3) Distance (m) Concentration (mol/dm

3) Distance (m)

2.5 18 2.2 -

2.6 14.76 2.3 14.63 & 9.76

3 14.38 2.5 13.50

4 8

Calibration curve

500 mL of water 400 mL of water

Concentration (mol/dm3) Distance (m) Concentration (mol/dm

3) Distance (m)

2.20 11.40 2.20 15.80

2.60 9.70 2.60 10.34

3.00 9.48 3.00 5.07

300 mL of water 200 mL of water

Concentration (mol/dm3) Distance (m) Concentration (mol/dm

3) Distance (m)

2.20 18.80 1.50 20.65

2.60 13.75 2.20 13.02

3.00 10.08 2.60 12.58

Graph 1: Linear correlations between concentrations of hydrochloric acid with distance travelled.

5. CONCLUSION

Combination of magnesium-copper voltaic cell as driving mechanism with magnesium-hydrochloric acid

stopping mechanism is possible to be applied on a model car in ChemEcar competition. From the results

obtained, future research is required to improve the performance of the car.

6. REFERENCE

1. List of battery types. Retrieved from http://en.wikipedia.org/wiki/List_of_battery_types

2. NurdRage. (2011). Make a zinc air battery. Retrieved from http://www.instructables.com/id/Make-a-

Zinc-Air-Battery/

3. Julia, F. (2011). Novel stopping mechanism nets prize in national Chem-E car competition. Retrieved

from http://www.bucknell.edu/x73073.xml

4. Ross, K. (2011). AIChE Chem-E-Car. Retrieved from http://aiche.students.mtu.edu/chemecar.htm

y = -5.8845x + 31.586 R = 0.9277

y = -5.0867x + 28.28

y = -6.3125x + 32.688

y = -13.413x + 45.276

y = -2.8423x + 20.933 R = 0.9248

y = -2.125x + 16.075

5.00

7.00

9.00

11.00

13.00

15.00

17.00

19.00

21.00

1.50 2.00 2.50 3.00 3.50 4.00

Dis

tan

ce t

rav

elle

d (

m)

Concentration of HCl (mol/dm3)

206 ml

200 ml

300 ml

400 ml

480 ml

500 ml