CHEMISTRY GLOSSARY
water hardness → tvrdoća vode
Hardness is defined as the concentrations of calcium and magnesium ions expressed in terms of calcium carbonate. These minerals in water can cause some everyday problems. They react with soap and produce a deposit called soap curd that remains on the skin and clothes and, because it is insoluble and sticky, cannot be removed by rinsing.
Hard water may also shorten the life of plumbing and water heaters. When water containing calcium carbonate is heated, a hard scale is formed that can plug pipes and coat heating elements. Scale is also a poor heat conductor. With increased deposits on the unit, heat is not transmitted to the water fast enough and overheating of the metal causes failure. Build-up of deposits will also reduce the efficiency of the heating unit, increasing the cost of fuel.
There are two types of water hardness, temporary and permanent.
Temporary Hardness is due to the bicarbonate ion, HCO3-, being present in the water. This type of hardness can be removed by boiling the water to expel the CO2, as indicated by the following equation:
Permanent hardness is due to calcium and magnesium nitrates, sulphates, and chlorides etc. This type of hardness cannot be eliminated by boiling.
| Water supply classification | |
|---|---|
| Hardness | Concentration of Calcium carbonate (mg/L) |
| Soft Water | 0 to 75 |
| Medium Hard Water | 75 to 150 |
| Hard Water | 150 to 300 |
| Very Hard Water | over 300 |
deionised water → deionizirana voda
Deionised water is water from which ionic salts have been removed by ion-exchange. It is used for many purposes as an alternative to distilled water.
| Type of water | Conductivity / µScm-1 |
|---|---|
| Ultrapure water | 0.05 |
| Distilled water | 0.5 |
| Tap water | 50 |
| Ocean water | 50 000 |
ionic strength → ionska jakost otopine
Ionic strength (μ or I) is a measure of the total concentration of ions in a solution, defined by
where zi is the charge of ionic species i and ci is its concentration.
aqueous solution → vodena otopina
Aqueous solutions are those solutions where water is the solvent. An aqueous solution found in an equation describing a chemical reaction is denoted by the state symbol, (aq).
complete ionic equation → potpuna ionska jednadžba
Complete ionic equation is a balanced equation that describes a reaction occurring in a solution, in which all strong electrolytes are written as dissociated ions.
conductivity → vodljivost
Conductivity is a measure of the ability of a material to conduct electric current.
crystal water → kristalna voda
Crystal water is water contained in certain salt crystals. It can be removed by heating. Crystals that contain crystal water are called hydrated and their salts hydrates.
ion exchange → ionska izmjena
Ion exchange is a process involving the adsorption of one or several ionic species accompanied by the simultaneous desorption (displacement) of one or more other ionic species.
mineral water → mineralna voda
Mineral water is a groundwater that rises to the surface through a natural opening in the earth or rock and contains a relatively high concentration of mineral ions and trace of elements which can be radioactive or thermal.
distilled water → destilirana voda
Distilled water is water purified by distillation so as to free it from dissolved salts and other compounds. Distilled water in equilibrium with the carbon dioxide in the air has conductivity of about 0.8×10-6 S cm-1. Repeated distillation in vacuum can bring conductivity down to 0.043×10-6 S cm-1 at 18 °C. The limiting conductivity is due to self ionisation
Citing this page:
Generalic, Eni. "Ionski produkt vode." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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