Corrosiveness of Different Types of Water

Inhalt

1. Introduction
1.1 Objectives/Aims
1.2 Methods

2. Experiment Layout
2.1 Synthetic seawater – chemical composition
2.2 Mineral water – chemical composition
2.3 CO₂Water – chemical composition

3. Visual Observations
3.1 Synthetic Seawater
3.2 Mineral Water
3.3 Mineral Water (CO₂added)

4. Discussion
4.1 Corrosion of Iron
4.1.1. Rust
4.1.2. Temperature Effect
4.1.3. pH Effect
4.2 CO₂Dissolved in water
4.2.1. CO₂corrosion mechanism
4.2.2. pH Effect
4.2.3. Temperature Effect

5. Conclusion

6. References

7. Annexes

List of Figures

Figure 1 – Synthetic Seawater

Figure 2 – Mineral water picture

Figure 3 – Sparkling water picture

Figure 4 – Iron nail immersed in synthetic seawater

Figure 5 – Iron nail immersed in mineral water

Figure 6 – Iron nail immersed in sparkling water

Figure 7 – Corrosion of iron in aerated water

List of Tables

Table 1 – Synthetic water chemical composition

Table 2 – Mineral water chemical composition

Table 3 – Sparkling water chemical composition

List of graphs

Graph 1 - Effect of pH on the corrosion rate of iron

Graph 2 – Pourbaix diagram of iron

1. Introduction

Corrosion of iron nails was analyzed through an observation experiment carried out in three different types of water to compare the difference in corrosiveness of some commercial drinking waters (mineral water, i.e. no gas, and sparkling water, i.e. with gas) and some synthetic seawater. The length period of observations was approximately 25 days.

Ph strip papers were used to measure the level of ph in the three different types of water. The frequency of ph measurement was every 3 to 4 days. Room temperature was logged and recorded every time ph measurement was taken. Details of the logbook table are available in the annex I.

1.1. Objectives

The aim of this report is to describe the corrosion of iron nails under stagnant water conditions. Observations, deductions and conclusions will be further detailed throughout the report.

1.2. Methodology

The methodology adopted to carry out this experiment, was through a combination of visual observations, supplemented by further research available on several studies carried out on corrosion phenomena.

2. Experiment layout

For this experiment 3 iron nails of 110mm x 2.5mm were polished with dry fine emery paper until nice and shiny. Two commercial drinking water (mineral water and sparkling water) and synthetic seawater were used as the aqueous environment. The commercial drinking waters were purchased at local supermarkets and the synthetic seawater was made via coursework Alternative B explanation.

2.1. Synthetic Seawater

Three table-spoonfuls of ordinary culinary salt dissolved in 1.3 litres of tap water on jug jar were used to make the synthetic seawater.

Due to lack of available equipment to measure the chemical composition of artificial seawater, the information shown on the table 1 below was taken from the work carried out by Kester et al.

Table 1 – Synthetic seawater chemical composition

Abbildung in dieser Leseprobe nicht enthalten

2.2. Mineral Water

The mineral water used for this experiment was bought at KERO supermarket. The brand name is Agua Perla, see figure 2. The chemical composition is shown on the table 2 as below.

Table 2 – Mineral water chemical composition

Abbildung in dieser Leseprobe nicht enthalten

Abbildung in dieser Leseprobe nicht enthalten

Figure 2 - Mineral water (Purchased at supermarket KERO)

2.3. Sparkling water (CO2 added)

The mineral water used for this experiment was bought at KERO supermarket. The brand name is FRIZE, see figure 3. The chemical composition is shown on the table 3 as below.

Table 3 – Sparkling water chemical composition

Abbildung in dieser Leseprobe nicht enthalten

Abbildung in dieser Leseprobe nicht enthalten

Figure 3 - Sparkling water – CO₂added (Purchased at supermarket KERO)

3. Visual Observations

Throughout the length period of the experiment the following visual observations were made and recorded as illustrated on the following sections.

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