Blue Fire Pointer S207 ISS Investigating the factor that affect electrolysis of saltwater and calcium carbonate: 1. Introduction

1. Introduction


What is electrolysis?
Electrolysis is the use of an electric current through an electrolyte to create a non-spontaneous chemical reaction. ( Song , 2015)

Global warming and climate changes is resulting in warmer water temperatures and this stress corals because they are very sensitive to changes in temperature. If water temperatures stay higher than usual for many weeks, the zooxanthellae they depend on for some of their food leave their tissue.Without zooxanthellae, corals turn white because zooxanthellae give corals their color. White, unhealthy corals are called bleached. Bleached corals are weak and less able to combat disease(Teach Ocean Science, 2015). Alas, they will die. But we found a solution to help the growth of the corals, this is through electrolysis. Electrolysis helps in the speeding up of the growth of corals

By electrolysis  would want to find out what are the factors that would affect the electrolysis of seawater and calcium carbonate. Calcium carbonate is a chemical compound with the formula CaCO3. It is formed by three main elements: carbon, oxygen and calcium. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells(Wikipedia, 2015). We are going to use the method (called Biorock technology) of applying low voltage through seawater, which causes dissolved minerals (calcium carbonate and magnesium hydroxide) in seawater to accumulate as white limestone on the frame (cathode). Thus coral larvae attaches to it and grows. There are many different factors, including the amount of voltage applied to the anode, the temperature of the seawater, the material of the anode.
First, what is electrolysis? In chemistry, electrolysis is the process by which ionic substances are broken down into simpler substances using electricity. During electrolysis, metals and gases may form at the electrodes. During electrolysis,
  • Positively charged ions move to the negative electrode. They receive electrons and are reduced (Thomas Goreau, 2015).
  • Negatively charged ions move to the positive electrode.  They lose electrons and are oxidised  (BBC, 2014).

Ionic substances in solution break down into elements during electrolysis. Different elements are released depending on the particular ionic substance. Since we are experimenting about electrolysis of seawater, the ionic substance in the solution is sodium chloride, NaCL. Predicting the product depends on the material of the negative electrode (cathode) and negative ion in the substance.

At the cathode, positively charged ions gain electrons, thus the ions have been reduced. Metal ions and hydrogen ions are positively charged. Whether the product of electrolysis is the metal or hydrogen depends on the position of the metal in the reactivity series. If the metal is less reactive than hydrogen, the metal will be produced, if it’s more reactive than hydrogen, hydrogen will be produced. Since our cathode is made out of iron, we predict that hydrogen will be produced at the cathode.

At the anode, oxidation takes place, as negatively charged ions lose electrons. For our experiment, the negative ion in the substance is chloride, Cl–, so we predict that the element given off is chlorine, Cl2.
Putting it together, we get hydrogen gas at the cathode and chlorine gas at the anode when the ionic substance in the solution is sodium carbonate during electrolysis of seawater.Thus, a solution of sodium hydroxide forms.

1.1 Research Questions 

The aim of our project is to find out what temperature of the seawater and which material of the anode will increase the rate of electrolysis.
The independent variables are the temperature of the seawater and the material of the anode used.
The dependent variable is the mass of calcium carbonate formed on the wire mesh.
  1.2 Hypothesis
For test on Anode:
The rate of electrolysis for the Aluminium anode would be the fastest, therefore, there more calcium carbonate would be deposited.
For test on Temperature:
The higher the temperature of the seawater, the more calcium carbonate will deposit because the rate of electrolysis is faster.

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