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HSAB is an acronym for "hard and soft (Lewis) acids and bases".HSAB is widely used in chemistry for explaining the stability of compounds, reaction mechanisms and pathways. It assigns the terms 'hard' or 'soft', and 'acid' or 'base' to chemical species.
A bathtub faucet with built-up calcification from hard water in Southern Arizona. Hard water is water that has a high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, [1] which are largely made up of calcium and magnesium carbonates, bicarbonates and sulfates.
Water softening is the removal of calcium, magnesium, and certain other metal cations in hard water. The resulting soft water requires less soap for the same cleaning effort, as soap is not wasted bonding with calcium ions. Soft water also extends the lifetime of plumbing by reducing or eliminating scale build-up in pipes
Hard water contains calcium and magnesium ions, which react with the surfactant anion to give these metallic or lime soaps. [1] 2 C 17 H 35 COO − Na + + Ca 2+ → (C 17 H 35 COO) 2 Ca + 2 Na + In this reaction, the sodium cation in soap is replaced by calcium to form calcium stearate. Lime soaps build deposits on fibres, washing machines, and ...
Stiff diagrams can be used: 1) to help visualize ionically related waters from which a flow path can be determined, or; 2) if the flow path is known, to show how the ionic composition of a water body changes over space and/or time. Example of a Stiff diagram. A typical Stiff diagram is shown in the figure (right).
The pressure on a pressure-temperature diagram (such as the water phase diagram shown above) is the partial pressure of the substance in question. A phase diagram in physical chemistry , engineering , mineralogy , and materials science is a type of chart used to show conditions (pressure, temperature, etc.) at which thermodynamically distinct ...
The diagram also shows how human water use impacts where water is stored and how it moves. [1] The water cycle (or hydrologic cycle or hydrological cycle) is a biogeochemical cycle that involves the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly constant over time.
The Mollier enthalpy–entropy diagram for water and steam. The "dryness fraction", x , gives the fraction by mass of gaseous water in the wet region, the remainder being droplets of liquid. An enthalpy–entropy chart , also known as the H – S chart or Mollier diagram , plots the total heat against entropy, [ 1 ] describing the enthalpy of a ...