Chlorine

Cl₂ reacts with active metals without heating, with other substances when heating:

2Sb + 5Cl₂ 2SbCl₅

Cu + Cl₂ CuCl₂

Important feature: at complete absence of moisture Cl₂ has no action on iron, therefore liquefied gas Cl₂ can be stored in steel bulbs.

Cl₂ is a strong oxidant. It reacts with non-metals, forming covalent chlorides:

2P + 5Cl₂ = 2PCl₅

2NH₃ + 3Cl₂ = N₂ + 6HCl

Interaction of Cl₂ with H₂ is an interesting example of the unbranched chain reaction:

Cl₂ + h = 2Cl^

Cl^ + H₂  HCl + H^

H^ + Cl₂  HCl + Cl^ and etc.

Here a single excited (?) Cl₂ molecule forms on the 100 thousand HCl molecules in average.

Highly explosive oil-like chloride of nitrogen, NI₃, is formed in the concentrated solution of NH₄Cl:

NH₄Cl + 3Cl₂ = NCl₃ + 4HCl

Chlorine has a positive charge in ₃ molecule. Chlorine gas demonstrates reducing properties only at interaction with F_2:

3F₂ + Cl₂ = 2

Reaction of chlorine with the halogens. Fluorine, F₂, reacts with chlorine, Cl₂, at 225°C to form the interhalogen species C1F. Chlorine(III) fluoride is also formed and the reaction does not reach its completion.

Cl₂(g) + F₂(g) = 2ClF(g) 225^oC

Cl₂(g) +3F₂(g) = 2ClF₃(g)

Under more forcing conditions, excess fluorine reacts with chlorine, Cl₂, at 350°C and 225 atmospheres pressure to form the interhalogen species C1F₅.

Cl₂(g) + 5F₂(g) = 2ClF₅(g) 350^oC, 225atm

Chlorine, Cl₂, reacts with bromine, Br₂, in the gas phase to form the unstable interhalogen species bromine(I) chloride, ClBr.

SO₂

Compounds of chlorine

Oxidation state	Name	Formula	Example compounds
−1	chlorides	Cl−	ionic chlorides, organic chlorides, hydrochloric acid
0	chlorine	Cl2	elemental chlorine
+1	hypochlorites	ClO−	sodium hypochlorite, calcium hypochlorite
+3	chlorites	ClO2−	sodium chlorite
+4	chlorine dioxide	ClO2
+5	chlorates	ClO3−	sodium chlorate, potassium chlorate, chloric acid
+7	perchlorates	ClO4−	potassium perchlorate, perchloric acid, magnesium perchlorate organic perchlorates, ammonium perchlorate, dichlorine heptoxide

hydrogen CHLORIDE. Pure HCl is a colorless gas with a repugnant smell, m.p. = -85.1^оС. It is easily liquefied at high pressure. HCl is soluble in water well: at 20 ^оС 2.5 volumes of HCl can be dissolved in 1 volume of H₂O. Aqueous HCl solution has name hydrochloric (historically, is also called muriatic) acid. HCl with water forms azeotropic boiling mixture, that contains 20.24% HCl. The commercial concentrated HCl contains 37% HCl, it has a density of  = 1.19 g/cm³. Hydrochloric acid belongs to the series of very strong acids.

Curious enough for water solution it is easy to find the approximate HCl percentage, simply multiplying on 2 the value after comma of the decimal fractional part of its density value. For example, at the density of 1.19 g/cm³ the percentage HCl will be equal 19^.2 = 38%. Consequently, and vice versa, knowing the percentage HCl in hydrochloric acid, it is possible to estimate approximately its density.

By preparation 1.184 N solution of HCl it is convenient to prepare medium with pH= 0 (at 25 ^oC).

Preparation:

In industry:

Pure: H₂ + Cl₂ = 2HCl

Technical purity: in great amount HCl is obtained as a by-product of chlorination of organic compounds:

RH + Cl₂ = R-Cl + HCl

where R is the organic radical.

Example: CH₄ + Cl₂ = CH₃Cl + HCl

In laboratory:

NaCl + H₂SO₄ = HCl + NaHSO₄ on cold

2

HCl corrodes materials and human hands

NaCl + H₂SO4 = 2HCl + Na₂SO₄ at heating