Why Metals Rust Chemistry

CHEMISTRY

Chemistry: Why Metals Rust

Table of Contents

Purpose and Hypothesis 2

Background Discussion 2

Materials 3

Methods of Procedure 5

Variables 5

Results 6

Discussion and Conclusion 8

References 9

Chemistry: Why Metals Rust

Purpose and Hypothesis

Rusting is considered to be an oxidation process in which a chemical reaction takes place. The metal reacts to the liquid poured over it, for example, water, in which oxygen creates a reaction over the metal, causing it to rust. The initial experiments by professors indicated that the investigation conducted by Crace Calvert in 1871 showed the first stage of rusting due to the presence of carbonic acid and its conversion to atmospheric oxygen since it is inherent in the moisture (Nature, 1906). Later, in 1898, another chemistry expert revealed that pure oxygen in the water attacks the iron that becomes the cause of ferrous oxide and hydrogen peroxide. A certain part of hydrogen peroxide converts ferrous oxide into rust, and the rest of the part directly comes in contact with the iron, which is seen in the form of corrosion.

The goal of this research is to evaluate what liquid rusts the metal the fastest. For this intent, a hypothesis is formulated, which is:

If water, orange juice, coke, apple juice, and vinegar are tested to see what liquid will rust the fastest, it is hypothesized that orange juice will rust the fastest. The reason is that it is the most acidic and carries the most amount of acid.

Background Discussion

Have you ever thought about why nails rust? How is the rust formed? To answer these questions, it becomes interesting to see what types of liquids would cause rust. Various metal objects are destroyed by rust, such as slates, bikes, and tools, etc. To prevent these objects from rusting quickly, a variety of liquids are observed for their reaction to the metal. It would help in deciphering how and what causes the metal objects to rust. Researchers have investigated that rust is a compound of iron oxide hydrate. Iron oxide is a chemical, and corrosion is an example of rusting (Grafen et al., 2015).

Research from old times has suggested that there are certain conditions under which rust takes place. The iron is not likely to rust when carbonic acid is not present (Nature, 1907). It has been witnessed that despite taking extra precaution that traces of carbonic acid are not there, the chemical reaction of liquid water and oxygen over the iron caused rust. It was assumed that alkalis could have given rise to the production of rust even when the carbonic acid was not there. However, there was another condition that polished iron when immersed in the solution of potassium dichromate, the rusting process is absent, and the surface of iron remains untouched (Nature, 1907).

Sine different conditions apply when rust has to take place on metal. The difference in the polished surface of the steel or iron nails has different results for rust or corrosion. For example, the common nail can continue to rust when exposed to air or water as the surface of the rustic layer is evident after some time in hydration (Lee, 2007). Electro-galvanized nails that are covered with zinc are not as tough to corrosion as hot-dipped nails. The coating surface on the nail protects the iron from rusting, and the iron’s holding power is prolonged. The vinyl coating extends this effect as the oxidization does not take place easily on the metal surface.

An investigation was run to check whether the rust is transferred from one surface to another, and the results showed that it is impossible (Micallef, 2019). Even if in a jar full of rusted nails and after shaking the jar, the surface of rusted nails could be damaged, but the rust cannot be transferred from one surface to another. Even if polished nails are kept within the jar, the surface of polished nails could be damaged with shaking and rubbing against the rusted nails, making them susceptible to being rusted. Otherwise, the results from the experiment itself did not reveal any rusting taking place in the absence of water and only by transferring from one area to another.

Waldman (2016) stated that exposure to dampness in the air creates rust. The production of hydrated oxide takes place from the reaction of oxygen with water that is present in the air. The rust cannot take place in dry air. Rust always occurs in moist air along with the presence of water. The chemicals of oxygen, iron, and water altogether create rust. Carbonic acid is formed by carbon dioxide (CO2) with a combination of iron, oxygen, and water. The acid reacts in a way that causes the breakdown of the iron. The breakdown is initiated by hydrogen, oxygen, and the water itself.

The chemical reaction that causes corrosion results in the breakdown of the metals, which is evident from the appearance of rust. Hollman & Wiberg (2001) explained that for the prevention of rust to happen, iron should be isolated from water and air.

Materials

The materials that would be required for the experiment include the following:

· 5 test tubes (numbered for all of the liquids)

· 1 test tube rack

· 5 steel nails

· Water

· Coke

· Apple juice

· Orange juice

· Vinegar

· Journal

Methods of Procedure

The procedure for the experimental research for checking which liquid is more acidic and has the highest probability of causing rust on steel nails is as follows:

i. The first step involves labeling test tubes with numbers and placing them on the test tube rack. The numbers are assigned in the order of number 1 being water, number 2 for coke, number 3 for apple juice, number 4 for orange juice, and number 5 for vinegar.

ii. The second step is placing one nail each in each of the empty test tubes.

iii. The third step is pouring each liquid according to its numbered test tube.

iv. The fourth step is about taking notes of which liquid is poured in what number of the test tube.

v. The next step is keeping a record for fifteen days about the condition of the nail in each liquid and each numbered test tube. The reactions will be analyzed in this journal.

vi. The next step is charting the results for liquid and its reaction on the steel nails in all test tubes.

vii. The final step is transferring the data onto a graph for a better demonstration of the findings.

Variables

The dependent variable is the steel nail or iron for this research, and the independent variables are several: water, coke, apple juice, orange juice, and vinegar. The reason for keeping steel nails or iron as a dependent variable is that they would be at the mercy of the type of liquid that would be poured on them and the type of reaction that would take place. The dependent variable is therefore highly reliant on the effect that would be created on it.

The reason for setting the liquids as independent variables since they would be the ones that are responsible for creating an effect, which is rust for this research, on the iron or steel nails. Since independent variables could be changed or manipulated, they are taken of various kinds so that each independent variable’s distinct impact could be noted on each steel nail.

Results

The following table shows the recorded results regarding the reactions of each liquid over the steel nails according to the numbered test tubes.

 Day

(1) Water

(2) Coke

(3) Apple Juice

(4) Orange Juice

(5) Vinegar

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

Rust

Rust

No Rust

Rust

No Rust

Rust

Rust

No Rust

Rust

No Rust

Rust

Rust

Rust

Rust

No Rust

Rust

Rust

Rust

Rust

No Rust

Rust

Rust

Rust

Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

Rust

Rust

No Rust

Rust

No Rust

Rust

Rust

No Rust

Rust

No Rust

Rust

Rust

Rust

Rust

No Rust

Rust

Rust

Rust

Rust

No Rust

Rust

Rust

Rust

Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

No Rust

Rust

Rust

No Rust

Rust

No Rust

Rust

Rust

No Rust

Rust

No Rust

Rust

Rust

Rust

Rust

No Rust

Rust

Rust

Rust

Rust

The table results show that vinegar has caused most of the rustic impact on the steel nail compared to the rest of the liquids. It is interesting to note that based on the belief that was deduced from the hypothesis, vinegar should have rusted the steel iron without any gaps of ‘no rust’ days in between. This phenomenon needs additional research as to why the vinegar first rusted the nail in the beginning days, then ‘no rust’ for two days in between, again rust for the next few days, and a recurring pattern continues till the last day. Moreover, the total number of days observed rust was equal for coke, apple juice, and vinegar. It is inferred that the hypothesis is negated that said orange juice would rust the metal the fastest. The observation was entirely in contrast with the hypothesis since the number of days where rust was shown the lowest for orange juice and highest for coke, apple juice, and vinegar, while none for water.

Discussion and Conclusion

For water to be considered ‘mineral water’, which is commonly used as drinking bottled water, the water needs to have a mineralization content of 1000 mg/L (Pietrucha-Urbanik, Skowronska & Papciak, 2020). The reason why the water did not cause rust over the steel nail could be due to the very factor that the presence of certain minerals prevented this process from happening. Since rust is caused by oxidizing with oxygen and carbon dioxide, the dissolution of metal might have been prevented due to dissolved gases such as hydrogen sulfide. The corrosion resistance needs additional exploration in a wide array of minerals and their reaction on steel iron or metal.