Investigating the Effect of Solution Nature on Metal Corrosion

This practical assignment investigates the effects of different solutions on metal corrosion. The experiment involves immersing iron nails in various solutions—coke, saltwater, and vinegar—and measuring the change in mass over a week. The results indicate that vinegar caused the most corrosion, while saltwater showed an increase in mass, possibly due to salt deposits. The experiment's findings align with the theoretical understanding of acid's impact on corrosion but highlight the complexities of saltwater's effect due to concentration. The discussion analyzes the results, compares them to the hypothesis, and suggests improvements, such as including a control experiment with pure water and controlling for temperature and solution concentration. The conclusion emphasizes the detrimental effects of corrosion and the importance of environmental control to minimize metal degradation.

Experiment on the Effect of Solution Nature on Corrosion
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Experiment on the Effect of Solution Nature on Corrosion
Introduction
Metals are elements that react by losing electrons to achieve stability. They are
characterized by varied unique properties that make them ideal in a diversified range of
application. They are generally malleable implying that they can be hammered without either
breaking or cracking. Generally, metals are electrical conductors, have higher density and better
thermal conductivity. Majority of the metals exist in the form of compounds such as oxides and
sulfates on earth (Tan et al., 2017). Despite the various desirable properties, performance of
metals in their varied applications are affected by corrosion.
All metals apart from the noble ones are chemically unstable when subjected to the
majority of the ordinary environment. Whenever a metal surface comes in contact with oxygen,
under certain circumstance, an unstable state of the metal is formed. This forms the basis of
corrosion. Corrosion is a natural process that converts refined metal to a more stable form (Jiang,
Sun, Keller, & Bond, 2015). More often corrosion is used in referring to electrochemical
oxidation of metal reaction with oxidants such as oxygen or sulfates. The concept of corrosion
explains the presence of oxides on metal surfaces. When metals are oxidized, they lose their
electrons to either oxygen or other chemicals in the air. Whenever oxidation of metal and
reduction of the chemical it is contact with takes place, the process is referred to as galvanic
corrosion (Otieno, Beushausen, & Alexander, 2016).
The impact of corrosion is common in daily experience. Corrosion is often responsible
for accidents in industries, homes, and highways. According to Qiao et al. (2016) corrosion costs
industrialized countries about 4-5% of the annual gross domestic product. Corrosion can lead to
a collapse of buildings, pipeline breaks, accidental fires in cases of electrical contact corrosion,
chemical plant leaks. Corrosion can also lead to blood poisoning when medical implants corrode.
AIM: To investigate how the environment affects the corrosion of metals by changing the
solution that the metal is stored in.
Hypothesis: It is expected that the saltwater nail will corrode more than the controlled variable
this is because saltwater makes metal rust more quickly than purer water as electrons move more
easily.

Materials:
1. 4x plastic cups
2. 4x nails (Iron, galvanized)
3. 1x electric scales
4. 150mL saltwater
5. 150mL coke
6. 150mL Vinegar
7. Weigh boat
8. Three wipes
9. 150ml measuring cylinder
Hazard Risk Management
Vinegar
Vinegar solutions can cause
itching when exposed to a
skin
Direct instruction from the
teacher
Care use of the solution.
Electric Short-circuiting of the
terminals can cause damage
Supervision of teacher
Correct use of the equipment
nail Sharp edges can cause
scratches
Direct instruction from
teacher
Correct use of equipment
Method
1. Weight each nail (Iron, galvanized).
2. Record the weight of the nail (Iron, galvanized).
3. Fill all four cups with solutions.
4. Make sure the solution has engulfed all four nails.
5. Leave nails in solution for one week.
6. Weight all four nails separately.

7. Recorded the weight of each nail with the solution labeled biased it.
Test Results:
solution Mass before (g) Mass after (g) Changing Mass
(g)
Observation (g)
Coke 2.39 2.38 -0.01
Saltwater 2.39 2.40 +0.01
Vinegar 2.45 2.42 -0.03
Discussion
The results of the investigation show that corrosion was more pronounced in vinegar
solution. The result on vinegar solution indicated a decrease in nail's mass by 0.03 grams
implying that an equivalent mass of as that decreased was corroded from the metal surface. A
solution of coke indicated corrosion of mass 0.01g. The mail immersed in a saltwater solution,
however, showed an increase in mass indicating that no resulting took place.
It is thus evident that the rate of corrosion is affected by the nature of corrosion. Just as
expected the nail subjected to vinegar solution would indicate the highest decrease in mass
because vinegar is made of 5-8% acetic acid which corrodes the nail’s surface since the acid in
vinegar reacts with both the iron and its oxide on the surface (Wang, Wang, Liu, & Zeng, 2016).
The nail subjected to saltwater was expected to have higher corrosion rate because the presence
of an electrolyte (salt) is known to accelerate reaction rates as it increases water conductivity and
effectively thus increasing ionic concentration which increases corrosion rates of the metal
surface. The increase in the mass of the nail immersed in a salty solution, however, did not show
this fact (Zheng & Zheng, 2016). This is probably because the solution was saturated and salt
particles ended up on the nails surface. Coke solution is showed corrosion but at a lower rate
because of possible corrosion.
In the experiment, it was expected that when the nail was subjected to vinegar and
saltwater, the corrosion rate could be high. The obtained results for the vinegar solution were in
line with the expectation while that of salty water deviated from the expectation probably
because of high salt concentration leaving salt on the nail surface leading to an increase in mass.

The results of the investigation were influenced by the concentration of the solution,
temperature, and solubility of temperature dependency of the solution. The results of the
investigations could be improved by include pure water as a control experiment. The
concentration of solution relative to the temperature under which the experiment is conducted
should be checked to ensure that no salt deposits clog the nail surface thus affecting the results.
Form the experiment, corrosion can be prevented and controlled by taking environmental
measures aimed at limiting exposure of the metal to an acidic solution. Other ways of controlling
and preventing corrosion include sacrificial coating, using corrosion inhibitors, using protective
coatings, using metals that are resistant corrosion and modifying metal components designs.
Conclusion
Corrosion is an undesirable process whose impacts are detrimental to o objects made of
metals. It converts refined metal into more stable forms inform of oxides, hydroxides, sulfates,
and other forms. This experiment was aimed at showing the effect of the nature of the solution
on corrosion. The result of the experiment indicates that corrosion is more pronounced in acidic
solution. The results on the concept of a salty solution on corrosion were however not confirmed.
This means that corrosion could be controlled and prevented by controlling the environmental
factor (nature of the solution). The findings of the experiments were in line with the theoretical
expectation on the impact of acid on corrosion. Acids contain hydrogen ions which react with
metals to form corresponding stable forms of oxides or hydroxide leading to corrosion. Effects of
salty solution which is theoretically known to characterize more pronounced corrosion were
however unconfirmed probably because of the high concentration. The experiment was,
however, a success since the effect of environmental factors on corrosion was explicitly studied.

Reference
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cracked concrete—Part II: Corrosion rate prediction models. Cement and Concrete Research, 79,
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Tan, X. R., Zhi, Q., Yang, R. B., Wang, F. Z., Yang, J. R., & Liu, Z. X. (2017). Effects of
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