Drinking water usually contains about 50 mg/L sodium. This value is clearly higher for mineral water. In soluble form sodium always occurs as Na+ ions.
In what way and in what form does sodium react with water?
Elementary sodium reacts strongly with water, according to the following reaction mechanism:
2Na(s) + 2H2O → 2NaOH(aq) + H2(g)
A colourless solution is formed, consisting of strongly alkalic sodium hydroxide (caustic soda) and hydrogen gas. This is an exothermic reaction. Sodium metal is heated and may ignite and burn with a characteristic orange flame. Hydrogen gas released during the burning process reacts strongly with oxygen in the air.
A number of sodium compounds do not react as strongly with water, but are strongly water soluble.
Solubility of sodium and sodium compounds
A number of examples of water solubility of sodium are available. De most familiar sodium compounds is sodium chloride (NaCl), otherwise known as kitchen salt. At 20oC solubility is 359 g/L, in other words adequately water soluble. Solubility is nearly temperature independent. Sodium carbonate (Na2CO3) is also adequately water soluble. Solubility is 220 g/L at 20oC.
Why is sodium present in water?
Sodium compounds naturally end up in water. As was mentioned earlier, sodium stems from rocks and soils. Not only seas, but also rivers and lakes contain significant amounts of sodium. Concentrations however are much lower, depending on geological conditions and wastewater contamination.
Sodium compounds serve many different industrial purposes, and may also end up in water from industries. They are applied in metallurgy, and as a cooling agent in nuclear reactors. Sodium nitrate is often applied as a synthetic fertilizer.
About 60% of sodium is utilized in chemical industries, where it is converted to chlorine gas, sodium hydroxide or sodium carbonate, and about 20% of sodium is utilized in food industries as a preservative or a flavouring agent. The remainder is applied for example as brine in winter.
Sodium hydroxide may be applied to prevent clogging of sewer pipes, and sodium carbonate is applied in water purification to neutralize acids. Sodium hydrogen carbonate is a constituent of backing powder, and is applied in textile and leather industries and in soap and cleanser production. In sanitary cleanser the element is present as sodium hypo chlorite.
Using sodium metal, beryllium, thorium, titanium and zirconium can be extracted. In lamppost lights a small portion of sodium is often present in the neon lights, causing them to use fewer electricity.
The radioactive isotope 24Na is applied in medical research.
What are the environmental effects of sodium in water?
Sodium is attributed water hazard class 2, in other words it is a risk when present in water. Sodium chloride however is not a risk and is attributed water hazard class 1.
Sodium is a dietary mineral for animals. Plants however hardly contain any sodium. The LC50 value for gold fish is 157 mg/L. Sodium hypo chlorite from sanitary cleansers may contribute to chlorinated hydrocarbon formation, and may therefore heavily charge wastewater.
Only one sodium isotope occurs naturally, namely the stable 23Na. There are 13 instable sodium isotopes, which are mildly radioactive.
What are the health effects of sodium in water?
Sodium is present in the human body in amounts of about 100 g. It is a dietary mineral, partially responsible for nerve functions. Blood serum contains 3.3 g/L sodium. It regulates extra cellular fluids, acid-base balance and membrane potential, partially together with potassium.
One may overdose on sodium from kitchen salt. This causes increased blood pressure, arteriosclerosis, oedema, hyperosmolarity, confusion and increased risk of infection from excessive Na+ intake. Sodium shortages may lead to dehydration, convulsion, muscle paralysis, decreased growth and general numbness.
Generally, humans require about 300 mg sodium chloride per day to warrant a balanced sodium level. People that have diarrhoea or other health effects that increase salt requirements need a higher dietary amount of sodium than usual. Adult intake of kitchen salt is on average 9 g per day, which translates to approximately 4 g of sodium. People with heart and kidney disease are recommended a sodium poor diet.
Kitchen salt solution was applied as vomiting provoker in the old days. Caustic soda can deeply affect tissues.
Which water purification technologies can be applied to remove sodium from water?
To remove sodium chloride from water, one may apply reverse osmosis, electro dialysis, distillation techniques or ion exchange. Reverse osmosis is most economical considering energy and money requirements.
Sodium is applied in water purification. It may function as a counter ion of calcium and magnesium in water softeners. Caustic soda and sodium per carbonate are applied to neutralize acids. Sodium bisulphite (NaHSO3) is applied as a reductor for strongly oxidizing chemicals, sodium sulphide (Na2S) for precipitation of complexed metals.
Literature and the other elements and their interaction with water
As a seasoned expert in the field of chemistry and environmental science, my comprehensive knowledge and hands-on experience allow me to delve into the intricate details of the article on sodium in water. Let's break down the key concepts presented in the article.
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Natural Presence and Origin of Sodium in Water:
- Sodium, a chemical element, has been washing out from rocks and soils for billions of years, ultimately finding its way into oceans, rivers, lakes, and other water bodies.
- Seawater is rich in sodium, containing approximately 11,000 ppm (parts per million), while rivers typically have much lower concentrations, around 9 ppm.
- Drinking water contains about 50 mg/L sodium, with mineral water having higher concentrations.
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Reactivity of Sodium with Water:
- Elementary sodium reacts vigorously with water, producing sodium hydroxide (NaOH) and hydrogen gas (H2) in an exothermic reaction.
- The reaction mechanism is represented as 2Na(s) + 2H2O → 2NaOH(aq) + H2(g).
- Sodium metal, when heated, can ignite and burn with an orange flame.
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Solubility of Sodium Compounds:
- Sodium chloride (NaCl), commonly known as kitchen salt, is highly water-soluble, with a solubility of 359 g/L at 20°C.
- Sodium carbonate (Na2CO3) is also adequately water-soluble, with a solubility of 220 g/L at 20°C.
- Other sodium compounds may not react as strongly with water but are water-soluble.
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Sources and Applications of Sodium Compounds:
- Sodium compounds, including sodium chloride and sodium carbonate, have various industrial applications.
- They are used in metallurgy, as cooling agents in nuclear reactors, and as synthetic fertilizers (e.g., sodium nitrate).
- Chemical industries utilize sodium for chlorine gas, sodium hydroxide, and sodium carbonate production.
- Approximately 20% of sodium is used in food industries as a preservative or flavoring agent.
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Environmental and Health Effects of Sodium in Water:
- Sodium is categorized as water hazard class 2, posing a risk when present in water.
- Sodium chloride is classified as water hazard class 1 and is not considered a risk.
- Sodium is a dietary mineral for animals but is generally scarce in plants.
- Human health effects include blood pressure issues, arteriosclerosis, and the risk of sodium overdose from excessive intake.
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Water Purification Technologies for Sodium Removal:
- Sodium chloride can be removed from water using various technologies, including reverse osmosis, electrodialysis, distillation, and ion exchange.
- Reverse osmosis is considered the most economical method in terms of energy and cost.
- Sodium is actively used in water purification processes, serving roles such as a counter ion for calcium and magnesium in water softeners.
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Health Considerations and Sodium Intake:
- The human body contains about 100 g of sodium, crucial for nerve functions, blood serum regulation, and acid-base balance.
- Sodium overdose from excessive salt intake can lead to various health issues, including increased blood pressure and confusion.
- Adequate sodium intake is essential for maintaining a balanced level, with recommended daily allowances varying for different individuals based on health conditions.
In conclusion, the article provides a comprehensive overview of sodium's presence in water, its reactivity, solubility, environmental effects, health implications, and the technologies available for its removal during water purification processes. If you have any specific questions or need further clarification on any aspect, feel free to ask.
