Test: Compounds of Hydrogen (Old NCERT) - NEET MCQ

Intracellular fluid (2/3 of body water) is fluid contained within cells. In a 72-kg body containing 40 litres of fluid, about 25 litres is intracellular, which amounts to 62.5%. Jackson's texts states 70% of body fluid is intracellular.

P₄O₁₀ (s) + H₂O (l) → H₃PO₄
Phosphoric acid is a weak acid with the chemical formula H₃PO₄. Orthophosphoric acid refers to phosphoric acid, which is the IUPAC name for this compound. The prefix ortho- is used to distinguish the acid from related phosphoric acids, called polyphosphoric acids.

2H₂O₂  2H₂O + O₂
The decomposition of hydrogen peroxide to produce oxygen and water. Laboratory method receiving of oxygen. This reaction takes place at a temperature of over 150°C or at room temperature and in the presence of a catalyst. In this reaction, the catalyst is can be sodium hydroxide, manganese(IV) oxide, platinum, copper.

Volume strength: This tells about the release of oxygen by 1 mL of hydrogen peroxide solution. Like, 10 volume of ​ H₂O₂ means, 1 mL of this solution will release 10 mL of oxygen.

• Temporary hardness is caused by the presence of dissolved bicarbonates of calcium, magnesium, and other heavy metals and the bicarbonates of iron. 
• The salts responsible for temporary hardness are Ca(HCO₃)₂ , Mg(HCO₃) Permanent hardness is due to presence of dissolved chlorides and sulphates of calcium, magnesium, iron and other heavy metals. 
• Temporary hardness is removed by boiling known as clark’s method. Permanent hardness cannot be removed by boiling so in that case we have to use ion exchange method and calgon’s method.

Uses of Hydrogen Peroxide:
(i) Antiseptic 
Hydrogen Peroxide has been used as an antiseptic for minor cuts, bruises, laceration etc for years. It actually foams when it comes in contact with blood. This helps in bringing up all the germs from within the cut. 
(ii) Bleaching
Hydrogen peroxide is extensively used for bleaching purposes. This also comes down to the oxidizing abilities of H₂O₂ . When a large organic molecule has a double bond this bond absorbs light.
(iii) Pollution Control Agent
Perhaps the most significant use of Hydrogen Peroxide is in environmental protection. It finds a use in air pollution control where it is used to treat effluents from industrial waste. It is also used in the restoration of aerobic conditions to sewage and industrial waste materials.

H₂O₂ is prepared industrially by oxidation of 2-ethylanthraquinol as it is very cheap.

Tempo​rary hardness: It is due to the presence of soluble bicarbonates of calcium and magnesium. It can be removed by boiling. During boiling, the soluble Mg(HCO₃)₂ present in water is converted into insoluble Mg(OH)₂ and Ca(HCO₃)₂ is changed to insoluble CaCO₃ which settle at the bottom as precipitates. These precipitates can be removed by filtration. Filtrate thus obtained will be soft water.
Reactions:

Hydrogen peroxide acts as both a reducing agent and oxidizing agent depending upon the nature of the reacting species. When H₂O₂ serves as an oxidizing agent, the oxygen of hydrogen peroxide (that is present in -1 oxidation state) is reduced to H₂O (-2 oxidation state).

The maximum density of water occurs at 4 °C because at this temperature two opposing effects are in balance.
Explanation: In ice, the water molecules are in a crystal lattice that has a lot of empty space. When the ice melts to liquid water, the structure collapses and the density of the liquid increases.