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Water Chemistry
Published in Frank R. Spellman, The Science of Water, 2020
As stated previously, symbols are used to identify elements. This is a shorthand method for writing the names of the elements. This shorthand method is also used for writing the names of compounds. Symbols used in this manner show the kinds and numbers of different elements in the compound. These shorthand representations of chemical compounds are called chemical formulas. For example, the formula for table salt (sodium chloride) is NaCl. The formula shows that one atom of sodium combines with one atom of chlorine to form sodium chloride. Let’s look at a more complex formula for the compound sodium carbonate (soda ash): Na2CO3. The formula shows that this compound is made up of three elements: sodium, carbon, and oxygen. In addition, there are two atoms of sodium, one atom of carbon, and three atoms of oxygen in each molecule.
Solids
Published in Elaine A. Moore, Lesley E. Smart, Solid State Chemistry, 2020
Neil Allan, Elaine A. Moore, Lesley E. Smart
Compounds of metals such as NaCl are classic insulators and we can readily qualitatively explain why this is so using our theory. In the simple ionic model an electron is transferred from a sodium atom forming Na+ to a chlorine atom forming Cl–. The highest occupied orbital is the chlorine 3p orbital, into which the electron has been transferred and the lowest unoccupied orbital is the sodium 3s, which has lost this electron. Similarly, in the molecular orbital theory, we have a full valence band made up of chlorine 3p orbitals and an empty conduction band higher in energy comprising sodium 3s orbitals. There is no partially full band, so NaCl is an insulator and does not conduct electricity. The band gap, the difference in energy between the full and empty bands, is very large (approximately 9 eV).
Subsurface Processes
Published in Stephen M. Testa, Geological Aspects of Hazardous Waste Management, 2020
A mole of any substance is the formula weight of the substance in grams. For example, the atomic weight of sodium (Na) is 22.99, so 1 mol of Na weighs 22.99 g. The atomic weight of chlorine (Cl) is 35.45, so 1 mol of Cl weighs 35.45 g. The molecular weight of common salt (NaCl) is 22.99 + 35.45 = 58.44, so 1 mol of NaCl weighs 58.44 g and contains 1 mol of Na and 1 mol of Cl. The atomic weight of oxygen (O) is 16.0, so 1 mol of O weighs 16.0 g; however, 1 mol of molecular oxygen (O2), which has a molecular weight of 32.0, weighs 32.0 grams and contains 2 mol of atomic oxygen. Nitrate ion (NO3−) has 1 mol of nitrogen (14.0 g), thus, 1 mol of NO3_ weighs 62 g. Note that electrons are essentially weightless, so the charge does not matter as far as weight is concerned.
Treatment of a clay soil deposited in saline water by cement
Published in European Journal of Environmental and Civil Engineering, 2021
A. R. Estabragh, M. Kouchakzadeh, A. A. Javadi
Sodium chloride is an ionic compound with chemical formula NaCl showing a 1:1 ratio of sodium and chloride ions. Sodium chloride is the salt most responsible for the salinity of seawater. On average, seawater has a salinity of about 35 g/L. Local lakes in some countries are in hypersaline condition. For example, the salinity of Urmia Lake in the northwest of Iran has risen to more than 300 g/L (Eimanifar & Mohebbi, 2007). Large quantities of sodium chloride are used in many industrial processes as well as de-icing of roadways in sub-freezing weather where salt enters the soil and changes the properties of the soil. Review of the literature shows that up to now, the effect of high salinity on the behaviour of sediments has not been studied. On the other hand, the deposited soil in high salinity water may be used as construction material such as borrow area or foundation for buildings. In such projects, it is necessary to understand the behaviour of these soils and also improve the mechanical properties of them. Therefore, solutions of sodium chloride with concentrations of 40, 80 and 150 g/L were selected. The measured values of pH for these solutions are nearly the same as drinking water.
NaCl and Na2SO4 solution effect on weathering steel visual appearance when the ambient temperature changes cyclically
Published in Cogent Engineering, 2019
Mindaugas Daukšys, Evelina Bitautaitė, Jūratė Mockienė, Dalia Nizevičienė
The EDS analysis confirms the same. Figure 5(c) illustrates that the highest amount of iron ions was found in corrosion products of samples kept in 3% NaCl solution. Cl anions are corrosion activators. According to Pedeferri (2018), they accelerate the corrosion of corrosion-resistant steels with Cr–Ni. The NaCl solution produces local corrosion, and the latter causes corrosive spots (pitting). Chloride anions activate corrosion more than sulphate anions. This is related to higher NaCl solubility in water than Na2SO4. The solubility of NaCl in water is 35.7 kg/100 kg of water, while the solubility of Na2SO4 is 4.76 kg/100 kg of water.
Extraction of rare earth elements from coal fly ash by alkali fusion–acid leaching: Mechanism analysis
Published in International Journal of Coal Preparation and Utilization, 2022
Mengcheng Tang, Changchun Zhou, Ningning Zhang, Jinhe Pan, Shanshan Cao, Tingting Hu, Wanshun Ji, Zhiping Wen, Tiancheng Nie
As can be seen from Figure 3b, there was no significant mass loss and heat change during the reaction of CFA with NaCl below 800°C. While at 800°C, the mass of the mixture was found to decrease rapidly, accompanied by a strong and narrow heat peak, which was due to the melting point of NaCl is 801°C. When the temperature exceeded the melting point of NaCl, NaCl melted, but the CFA remained unchanged.