Sodium Hydroxide

Properties of (NaOH) Physical ☻It is solid substant has a white color. ☻Dissolve easily in water and give a high heat. ☻It is substant (Absorb moisture from atmosphere). Chemical ☻React with acids {HCL, H2SO4} and acidic oxide {CO2, SO2} (Acids)→NaOH+HCl (Acids)→ NaOH (solu) +H2SO4

NaCL+H2o NaHSO4+H2o

(Acidic oxide)→ NaOH (solu) + CO2 NaHCO3 +NaOH

NaHCO3 Na2CO3+H2o

(Acidic oxide)→ NaOH (solu) +So2 NaHSO3 +NaOH

NaHSO3 Na2SO3+H2o

FOR NOTE: If we use {NaOH (molten)} the rate of reaction will increase but depend On the kind of salt. ☻React with salt solution and amphoteric salt → 2NaOH+ CuSo4 → 6NaOH + Fe2 (SO4)3

Na2SO4 +Cu (OH) 2 ↓ 3Na2SO4 +2Fe (OH) 3 ↓

(Amphoteric salt)→ 6NaOH+AL2(SO4)3 → NaOH+ 2AL(OH)3

3Na2SO4 +2AL(OH)3↓ NaALO2 +2H2O

FOR NOTE: (SODIUM META ALUMINATE) is {NaALO2} (Ammonium salt)→ NaOH+NH4CL (heat) NH4OH

NaCL + NH4OH NH3 + H2O

FOR NOTE: The last reaction is reversible so that it necessary to heat it to give that Product (NH3).

☻React with element React with non-metal and product depends on the temp.of solu. . → (with chloride gas on cold) → CL2 +H2O NaOH+HCL NaOH +HCLO

HCL+HCLO NaCL + H2O NaCLO +H2O

CL2 +2 NaOH (solu) FOR NOTE:

NaCLO HCLO

NaCLO+NaCl+H2O

{sodium hypochlorite} {hydrochloride}

→ (with chloride gas on heating) → 3CL2 +3H2O 5NaOH+5HCL NaOH +HCLO3

5HCL+HCLO3 5NaCL +5H2O NaCLO3 +H2O

3CL2 +6 NaOH

5NaCL +NACLO3+3H2o

React with amphoteric metal like (AL, Zn, and Pd): → 3NaOH (fuse) + AL

Na3ALO3+3/2 H2 ↓ {Sodium aluminates}

FOR NOTE: the hot solution will make the reaction very slowly so that we use fused (NaOH) with such metals to make it very rapid Uses of sodium hydroxide ☻ In paper industry where it dissolve lignine {which holds the fibers wood together}. ☻ In tanning of leather where it dissolves the binding material between the fibers . ☻ In petroleum product where it clear it . ☻ In organic where it favored the artificial fibers (viscose) and natural (cellulosic) . ☻ In making a shine layer.

☻The main field of uses of it is {soap} and {glycerol} CH2 – COOR + NaOH CH2-OH │ │ CH – COOR + NaOH CH-OH + 3RCOONa │ │ CH2 – COOR + NaOH CH2-OH ↓ ↓ ↓ ↓ {Ester of a {caustic {glycerol} {soap} Tribasic soda} Organic acid} → like (plamitic, stearic, oleic acid)

Industrial preparation

☻NaOH is prepared by electrolysis of a brine solution in a cell having graphite anode and a cathode made from platinum: Na++CL-

NaCL (solution) At anode

2CL-

At cathode

Na+ +e

Na

Na+H2o

NaOH+1/2 H2

CL2+2e

☻NaOH we get it from sea water by precipitate the {calcium, magnesium} By carbonate solution Na2CO3 +CaAL2 Na2CO3 + MgCL2

☻ {CL2} and {H2} are by-product

∆

CaCO3 +2 NaCL ∆ MgCO3 +2NaCL ↓ {Precipitate}