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  2. Carbonate hardness - Wikipedia

    en.wikipedia.org/wiki/Carbonate_hardness

    Carbonate hardness, is a measure of the water hardness caused by the presence of carbonate (CO 2− 3) and bicarbonate (HCO − 3) anions. Carbonate hardness is usually expressed either in degrees KH (from the German "Karbonathärte"), or in parts per million calcium carbonate ( ppm CaCO 3 or grams CaCO 3 per litre|mg/L).

  3. Hardnesses of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Hardnesses_of_the_elements...

    Mohs hardness of materials (data page) Vickers hardness test; Brinell scale This page was last edited on ...

  4. Carbon dioxide (data page) - Wikipedia

    en.wikipedia.org/wiki/Carbon_dioxide_(data_page)

    log of Carbon Dioxide vapor pressure. Uses formula ... Carbon dioxide liquid/vapor equilibrium thermodynamic data: Temp. °C P vap Vapor pressure kPa

  5. HSAB theory - Wikipedia

    en.wikipedia.org/wiki/HSAB_theory

    In 1983 Pearson together with Robert Parr extended the qualitative HSAB theory with a quantitative definition of the chemical hardness as being proportional to the second derivative of the total energy of a chemical system with respect to changes in the number of electrons at a fixed nuclear environment: [11]

  6. Carbonic acid - Wikipedia

    en.wikipedia.org/wiki/Carbonic_acid

    In even a slight presence of water, carbonic acid dehydrates to carbon dioxide and water, which then catalyzes further decomposition. [6] For this reason, carbon dioxide can be considered the carbonic acid anhydride. The hydration equilibrium constant at 25 °C is [H 2 CO 3]/[CO 2] ≈ 1.7×10 −3 in pure water [12] and ≈ 1.2×10 −3 in ...

  7. Carbonate - Wikipedia

    en.wikipedia.org/wiki/Carbonate

    A carbonate is a salt of carbonic acid, (H 2 CO 3), [2] characterized by the presence of the carbonate ion, a polyatomic ion with the formula CO 2− 3.The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group O=C(−O−) 2.

  8. Calcium carbonate - Wikipedia

    en.wikipedia.org/wiki/Calcium_carbonate

    Calcium carbonate is a chemical compound with the chemical formula Ca CO 3. ... releases carbon dioxide upon ... which has the relatively low hardness level of 3 on ...

  9. Carbon dioxide - Wikipedia

    en.wikipedia.org/wiki/Carbon_dioxide

    Carbon dioxide is soluble in water and is found in groundwater, lakes, ice caps, and seawater. It is a trace gas in Earth's atmosphere at 421 parts per million (ppm), [a] or about 0.042% (as of May 2022) having risen from pre-industrial levels of 280 ppm or about 0.028%.