Failure Of Seawater Circulating Pump Sleeves
Seawater circulating pump sleeves are prone to wear and are prone to serious corrosion when running in seawater with a high rotation speed. The original hardening method of a seawater circulating pump sleeve is to spray Doloro 6325 M or cermet on to the outer ring of the sleeve. Theoretically, the anti-seawater corrosion resistance and hardness of the coating are pretty good. However, due to inevitable microscopic pinhole problems, loose structure and non-metallurgical bonding between the coating and the substrate, seawater can easily get into the combining gap, causing corrosion, pitting and even punching, finally leading to spalling of the spray coating. Figure 9.34 shows an example of a sleeve with a spalled coating.
9.34. Scene of the sleeve with spalling coating.
R.W. Baker, B.T. Low, in, 2015
Other Names For Water
The IUPAC name for water is, actually, water. The alternative name is oxidane. The name oxidane is only used in chemistry as the mononuclear parent hydride to name derivatives of water.
Other names for water include:
- Dihydrogen monoxide or DHMO
- Hydrogen oxide
- The polarized form of water, H+ OH-, is called hydron hyroxide.
The word “water” comes from the Old English word wæter or from the Proto-Germanic watar or German Wasser. All of these words mean “water” or “wet.”
Adaptation To Saltwater Intrusion In Coastal Agricultural Land
As saltwater intrusion on agricultural lands has led to crop productivity declines, land managers have responded in several ways, including abandoning land or enrolling it in easements, adding water control structures , switching to alternative crops , adjusting agricultural inputs , and applying gypsum to displace sodium ions and improve drainage . Adaptation choices include the types of management changes and the timing of those changes. Some choices may require land managers to weigh costs and benefits only in the short-term , whereas others may require evaluation over the long-term .
Other options are to enroll abandoned agricultural lands in conservation easements or to restore wetland vegetation and control invasive species. Landowners might be motivated to restore wetland vegetation to obtain tax savings or other financial incentives or to obtain recreational opportunities such as hunting. As the productivity of agricultural land declines with saltwater intrusion, the opportunity cost of engaging in conservation or other land uses also declines, reducing the needed incentives to restore wetlands. However, federal, state, or local governments, or nongovernmental organizations may want to target incentives to enhance the transition of coastal farmland to wetland.
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Expansion Of Invasive Species
Given the habitat preferences of some widespread invasive plant species for moderate salinity and the high salinity tolerance of others , and many prominent invasive species are likely to expand their ranges in coastal areas because of saltwater intrusion.
In the eastern United States, the invasive haplotype of Phragmites australis is positioned to be a dominant species in salt-affected, retreating coastal ecosystems. It grows at the upland edge of tidal wetlands, is relatively salt-tolerant and is highly opportunistic . In Delaware Bay, roughly half of the area of forest retreat now accommodates P. australisdominated marsh . In contrast, in lawns transitioning because of saltwater along the Connecticut coast, private landowners are inadvertently controlling the spread of P. australis through mowing . During marsh migration, P. australis is replacing native high marsh species and contributing to coastal squeeze of native tidal marsh communities. In temperate Atlantic Coast marshes, P. australis expansion will most affect the high marsh dominant Spartina patens. A S. patensassociated endemic species, the saltmarsh sparrow, Ammodramus caudacutus, is predicted to go extinct within the next several decades . In summary, with increasing saltwater intrusion, many salt-tolerant invasive species are poised to colonize new areas and expand their range.
Materials For Each Group
Point out that several water molecules can arrange themselves near an ion and help remove it from the crystal. Show students that the positive area of a water molecule will be attracted to the negative chloride ion and that the negative area of a water molecule will be attracted to the positive sodium ion.
Model how water dissolves salt
Look at the pictures showing how water molecules dissolve salt. Then arrange the water molecules around the sodium and chloride ions in the correct orientation. The positive part of the water molecules should be near the negative chloride ion. The negative part of the water molecules should be near the positive sodium ion.
Point out that the water molecules are attracted to the sodium and chloride ions of the salt crystal. Explain that the positive area of a water molecule is attracted to a negative chloride ion. The negative area water of a water molecule is attracted to a positive sodium ion. Dissolving happens when the attractions between the water molecules and the sodium and chloride ions overcome the attractions of the ions to each other. This causes the ions to separate from one another and become thoroughly mixed into the water.
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Agricultural Productivity Decline And Field Conversion
Very few crops can grow in sustained conditions of greater than 2 parts per thousand salinity , which is substantially below the salinity levels in many salt-intruded fields . For example, crops such as corn and soy Merr.) have suffered yield declines with saltwater intrusion . Because of the episodic nature of saltwater intrusion and the variation in tolerance of crops, coastal croplands can exhibit gradual or sudden declines in productivity . When farming practices of tillage or herbicide application continue during the initial stages of saltwater intrusion, fields often exhibit large bare areas in which crops cannot tolerate the saline conditions and the farm practices kill colonizing noncrop plants. Abandoned, salinized farmland, which has high nutrient levels , low organic matter, and a seed bank of opportunistic annuals, can be rapidly colonized by annual graminoids and herbs, including many agricultural weed species . On the arid Pacific Coast of Baja California, for example, abandoned agricultural land is rapidly colonized by the invasive and highly salt-tolerant ice plant, Mesembryanthemum crystallinum .
Researchers Develop A Simple Way To Remove Salt And Some Other Dissolved Substances From Polluted Water
Researchers have developed a new way to remove salt and some other dissolved substances from water. This could help purify tainted groundwater or desalinate seawater.
By Sid Perkins
The worlds population is ever rising. And the more people there are, the more need there is for clean drinking water. Now, researchers have come up with a new way to remove many pollutants from water, including salt: They zap it.
The oceans hold about 97 percent of Earths water. Its salt content makes it undrinkable. Other water that is pumped from underground often has minerals dissolved in it. So this water, too, can be undrinkable . Scientists have developed many methods to remove impurities from water. But those methods often take lots of energy. And that makes them costly.
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Salt Water Pool Chemistry Charts
Salt water pool chemistry is the key aspect aspect of pool ownership that ensures your pool is safe for swimming and is properly balanced. There are several key components of balancing your water that youll need to become familiar with but the good news is that management of water chemistry tends to be easier with a salt water pool than with a regularly chlorinated pool.
Salt water pool chemistry involves balancing salt level, pH, Total Alkalinity, Cyanuric Acid and Total hardness while keeping chlorine levels between 1 ppm and 3 ppm.
Your salt water chlorinator will help to manage the water chemistry and once you have it under control it tends to run fairly consistently except when events occur such as heavy rainfall or water loss through evaporation which requires you to add water. Once you put one chemical in your pool, it may throw another one out of whack so before you do so, check with your pool company for their advice.
Here are tables for the most critical aspects of salt water pool management for the most common pool sizes in gallons of water:
- Salt level
- Cyanuric Acid level
- Total hardness
Depending on whether your levels are low or high, you might need to make an adjustment and add something to the water to bring the level inline.
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But Martin Bazant and his teammates have come up with a new method that could lower the cost. Bazant works at the Massachusetts Institute of Technology in Cambridge. And as a chemical engineer, he uses chemistry to solve problems related to the production of food, fuel and other products. Many of the methods now used to separate fresh water from salty use some sort of barrier, such as a filter. Those barriers often are designed to let water pass through, but block larger atoms, such as sodium and chlorine.
Bazants group instead made a system that doesnt use physical barriers. It takes advantage of the fact that sodium and chlorine particles have an electrical charge. Charged particles are called ions. And the new system uses electricity to steer the ions dissolved in water in a particular direction. This separates them from a stream of fresh water. Bazants team published its results November 3 in Environmental Science and Technology Letters.
Heres how it works
The system only steers charged particles. So it wont remove pollutants that have no electric charge. And the now extra-salty portion of the water will need to be treated as a waste.
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Why Salt Water Is A Mixture Not A Compound
Saltwater is a homogeneous solution comprising of two different compounds namely sodium chloride and water. Unlike a compound that has strong chemical bonds, there is no chemical bonding between water and salt molecules in saltwater.
Salt can be separated from saltwater by evaporating the water. Only mixtures can be separated by physical means. The salt particles in salt water cant be seen with naked eyes.
In a compound, the properties of constituent atoms are lost. In the case of saltwater, it is not so. The salt still has its salty taste and water remains in a liquid state itself.
Also, saltwater taken from different sources can have different concentrations of salt. There is no formation of a new pure substance on dissolution.
All these are possible only because salt water is a mixture and not a compound.
Drivers Of Saltwater Intrusion
Saltwater intrusion and the degree of upland salinization are driven by five main factors: the position of sea-level relative to the land and water table, the frequency and magnitude of storms and tides, the frequency and duration of drought, water use , and hydrologic connectivity . Because each of these five factors are themselves variable in space, time, frequency, and duration, the process of ecosystem salinization is extremely dynamic and can occur slowly or quickly, depending on the unique combination of drivers acting on any particular location. For example, sea salts may be delivered slowly to coastal ecosystems through groundwater exchange, surface water mixing, and tidal pumping or rapidly during extreme events like hurricanes and tsunamis.
Drivers of salinization in uplands, three primary components of salinization, and their effects on biogeochemistry, plant communities, and ecosystem services.
Illustration of shallow coastal system undergoing saltwater intrusion. Coastal saltwater intrusion is caused by relative sea-level rise, water management , the connectivity of creeks and ditches to the source of saltwater, the frequency of rainfall and drought events, and storms and tides.
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As A Demonstration Show Students A Magnified Picture Of Salt Crystals
Remind students that they have seen the particles of a liquid and solid interact when water dissolved the sugar from an M& M . Explain that in this activity, students will investigate how water dissolves salt crystals. They will also explore how the water from the salt solution evaporates, and how the dissolved salt forms back into crystals again.
Show the photo: Magnified salt .
Explain that this is a magnified picture of salt crystals. Tell students that each salt crystal is made up of two different types of particles called sodium ions and chloride ions. Tell students that ions are atoms or molecules that have either a positive or negative charge.
What Is Chemistry And Why Is It Important To The Study Of Marine Biology
Much of chemistry falls into 3 categories: inorganic, organic and biochemistry, which are all very useful to Marine Biologists.
Inorganic chemistry is often defined as the study of compounds that do not contain carbon however, some non-living matter, diamonds for example, contains carbon and therefore falls outside the rule. Marine biologists who study the minerals that seep from hydrothermal vents would use inorganic chemistry.
Broadly speaking, organic chemistry has been defined as the study of compounds that occur naturally from plants and animals and inorganic chemistry as the study of compounds created by non-living elements such as those found in minerals.
Organic chemistry is also defined as the chemistry of compounds that contain both carbon and hydrogentwo elements found in all living things. The majority of marine science related chemistry would fall under organic chemistry.
Methane is a saturated hydrocarbon that consists of a single carbon atom bonded to four hydrogen atoms. The molecule assumes a tetrahedral geometry, and is nonpolar.
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Salt Water Battery Chemical Reaction
The positive and negative electrodes are separated by a chemical electrolyte, which in this experiment was liquid . However, the batteries that are used in daily life contain dry powder as an electrolyte. The chemical reaction starts as soon as you switch on the electrical device connected to the battery. The positive ions and electrons are created on the negative electrode because of the reaction. The positive ions enter the electrolyte and electrons travel through the circuit to the positive electrode, where they light up the device. On the positive side, a chemical reaction is taking place in which arriving electrons combine with ions and emit out of the electrolyte to complete the circuit.
The Density Of Sea Water
It’s understandable why seawater is denser than pure or fresh water – the salts increase the mass.
As a result, people, animals, and objects will float easier in salt water than in fresh water.
And, because it has higher density levels, the water from the oceans freezes at around -2 °C .
Its viscosity – i.e., internal resistance to flow – is also higher than that of fresh water.
Sea water’s average pH typically ranges between 7.5 and 8.4, making it slightly alkaline.
However, the negative impact of climate change and global warming are making the oceans of the world more acidic, resulting in, for example, the death of the corals.
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Law Of Definite Proportions
The law of definite proportion also called Prousts law, or the law of constant composition states that a given chemical compound always contains its component elements in a fixed ratio by mass and does not depend on its method of preparation and source.
Let me explain this law with the help of water. Water is a compound formed from 2 atoms of hydrogen and 1 oxygen atom.
The molecular mass of water is 18g out of which oxygen accounts for the 16g and hydrogen for the remaining 2g. It can be seen that hydrogen and oxygen combined in a fixed ratio of 2:1.
Water can be formed only if 2 hydrogen atoms combine with 1 oxygen atom. Instead of 1 atom, if it combines with two oxygen atoms, we get a different compound called hydrogen peroxide or H2O2.
Even if we take water from different sources, it would have the same molecular mass with 2 hydrogen atoms and 1 oxygen atom.
When elements combine to form compounds, they lose their individual properties and the newly formed compound has properties entirely different from its constituent elements.
Let me elaborate this statement with an example for your better understanding.
Oxygen is an element that is necessary for combustion. Hydrogen is an element that is highly flammable. It has the highest value on the flammability scale. It is also used as fuel.
Surprisingly, the compound formed from oxygen and hydrogen, that is water, extinguishes fire. It doesnt support combustion at all.
Introduction To Chemistry And Seawater
Salt evaporation ponds on the shores of San Francisco Bay illustrate a variety of processes and the connections between physical, chemical, and biological aquatic science . In the open ponds, water evaporatesmolecules of water escape from the ponds into the atmosphere. As water evaporates, salt is left behind. The more water that evaporates from the ponds, the higher the salinity of the water remaining becomes. Very salty water is called hypersaline water. Different microorganisms are able to survive and thrive in the ponds at different levels of salinity. These organisms include red and green algae and orange brine shrimp. When all of the water has evaporated from salt water, only crystallized white salt remains. This can be seen along the edge of the pond on the bottom right of Fig. 2.1. Dissolving, evaporating, crystallizing, metabolizing, photosynthesizing, and respiringall of these are processes are made understandable by knowing how atoms and molecules interact. Water plays a special role in these processes. Understanding the chemistry of seawater leads to a better understanding of the nature of and interactions of molecular matter.
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