Silver Nitrate (AgNO3) Properties and Uses

Silver Nitrate (AgNO3)

• Silver nitrate is a frequently used organic silver salt in medicine.
• It exhibits astringent, antibacterial, and caustic activity.
• It is an odorless, white crystalline powder or transparent colorless crystals.
• Silver nitrate has a bitter metallic taste.
• It decomposes at 444°C into metallic silver, nitrogen, oxygen, and nitrous oxide.
• Silver nitrate is toxic and corrosive.
• Its solubility in water and alcohol increases with temperature.
• It is not photosensitive in its pure form, but turns grey or grayish black when exposed to air or light.
• Silver nitrate is not hygroscopic.
• It is incompatible with organic materials, alkalis, halogen acids and their salts, tannins, phosphates, and benzalkonium chloride.
• Silver nitrate is not available in any combination preparations.
• It gives black stains on skin, tissues, and fabric, so avoid direct contact.
• Crystals can be produced by dissolving silver metal in nitric acid and evaporating the solution.
• Silver nitrate is used in organic synthesis.
• It is used as a stain in scanning electron microscopy.
• Pharmaceutical uses include management of infections in burn wounds and epidermal necrolysis.
• Silver nitrate is used for cauterization of warts.
• It is used for prophylaxis of gonococcal ophthalmia neonatorum.
• Silver nitrate is used for treatment of eczematous reaction.
• It can be used for prophylaxis of genito-urinary tract infections.
• It functions as a disinfectant, astringent, and caustic agent.
• It is an antiseptic with a broad spectrum, especially against organisms that invade burn wounds; thus, it is successfully used in managing severe burns.
• AgNO3 is a precursor to many silver compounds.
• Previously called 'lunar caustic' because silver was called luna (moon) by ancient scientists.
• AgNO3 reacts with NaOH to give dark grey silver oxide: 2 AgNO3 + 2NaOH -> Ag2O + 2NaNO3 + H2O.
• It reacts with halides (Cl, Br, I) to give insoluble silver halides: Ag(+) + X(-) (aq) -> AgX.
• Its aqueous solution gives white precipitates with sodium chloride: AgNO3 (aq) + NaCl (aq) -> AgCl(ppt).
• Contraindications include Hypersensitivity and avoiding prolonged contact with skin due to staining.
• Silver nitrate may irritate skin & mucous membranes.
• Do not irrigate eye after application of 1% solution. Chemical burns may result from inappropriate use.
• Skin contact time with applicators should be minimal when used in thin delicate skin or neonates.
• It is an Antiseptic that denatures proteins, acting on the surface of bacteria and causing substantial changes in cell wall and membrane.
• Adverse drug reactions (ADRs) include burning and skin irritation, staining of the skin, methemoglobinemia (presence of methemoglobin in RBCs; hemoglobin containing ferric form instead of ferrous), vomiting, diarrhea, shock, metallic taste, and coma.

Iodine (I₂)

• Atomic symbol: I
• It is bluish black or dark purple with a pungent odor and sharp acrid taste.
• It is corrosive in nature.
• It sublimes at room temperature, forming violet corrosive vapors.
• It is very slightly soluble in water but soluble in aqueous solutions of iodides.
• The name iodine comes from the Greek word 'ioeides,' which means violet or purple.
• When heated to decomposition, it emits toxic fumes of hydrogen iodide and various iodine compounds.
• Only one of the 37 known isotopes is stable (127I).
• The optimal method to determine iodine (I2) levels is to measure the amount in urine samples.
• Iodinization of water supply and the use of iodized salt have been the mainstay of treatment.
• Iodine reacts with water to form hypoidoite: I2(l) + H2O(l) -> OI-(aq) + 2H+(aq) + I-(aq).
• Iodine reacts with fluorine to form Pentaflouride Iodine: I2 + 5 F₂ → 2 IF₅ .
• It reacts with bromine to form very unstable low MP solid: an inter-halogen specie, iodine (1)bromide: Br₂(l) + I₂(s) → 2IBr(s).
• With hot conc. Nitric acid, it forms iodic acid: 3I₂(s) + 10HNO₃(aq) → 6HIO₃(s) + 10NO(g) + 2H₂O(l).
• It reacts with hot aqueous alkali to produce iodate, IO3-: 3I₂(g) + 6OH-(aq) → IO₂-(aq) + 5I-(aq) + 3H₂O.
• It's a strong oxidizing agent.
• The RDA of iodine is 150 µg for adult males/females and 220 µg during pregnancy and lactation.
• The body does not make iodine since it is needed for the production of thyroid hormone.
• I2 deficiency can cause goiter (patient may experience choking and difficulty in swallowing and breathing).
• Hypothyroidism may develop because of deficiency.
• It can cause problems during pregnancy like miscarriages, stillbirth, and congenital abnormalities are linked.
• The pharmaceutical applications include its presence in almost all body sterilization products.
• As a wound cleaner, it helps to purify water in tablet or liquid form.
• It helps in preventing goiter.
• Iodine tonic is helpful as a throat gargle for cough (1%).
• Helps in treating many eye conditions and works as a protectant against UVB radiation.
• Present in 131I-metaiodobenzylguanidine (131I-MIBG) for imaging and treating pheochromocytoma (tumor of adrenal gland tissue) and neuroblastoma.
• Used in diagnostic scanning, treatment of hyperthyroidism and radiootherapy for treating thyroid cancer.
• Potassium iodide (KI) is given during radiation therapies to avoid excess loss of the thyroid gland in thyroid cancer treatment.
• Tincture of iodine is used as an antiseptic and disinfectant to help treat bacterial infections, minor burns, and cuts (2-7%).
• Povidone iodine is an antiseptic containing 9-12% iodine, which is used for cleaning wounds and post-operative stitches.
• Levothyroxine - is the drug of choice for hypothyroidism
• Iodine compound erythrosine, also known as Red No.3 E127, is used as a food coloring agent, printing inks, a biological stain, and a dental plaque disclosing agent.
• Excessive iodine intake can lead to problems like stomach and mouth issues, including abdominal pain, metallic taste, and a burning feeling in the throat.
• Hypothyroidism can occur when excess iodine interferes with the manufacturing of thyroid hormones, resulting in low thyroid hormone levels, weight gain, fatigue, and dry skin.
• Using potassium iodide and lithium together may cause hypothyroidism.
• When taken with ACE inhibitors, Potassium salts of iodine causes an increased level of potassium in the body
• Use of potassium iodide with warfarin makes warfarin less effective.

Hydrogen peroxide (H2O2)

• Hydrogen peroxide is the simplest peroxide with an oxygen-oxygen single bond.
• It is a colorless, weak acid with bleaching properties.
• It can produce burns and irritation on the skin.
• It can cause severe damage to the eyes when used above 6%.
• In pure form, it is a clear liquid with a slightly sharp taste, slightly more viscous than water.
• Soluble in water and ethyl alcohol and insoluble in petroleum ether
• Hydrogen peroxide is a strong oxidizing agent.
• It possesses anti-microbial properties and is used as a sporicidal sterilant and deodorant disinfectant.
• It softens ear wax.
• It is also used in anti-acne treatments
• It helps clean wounds.
• Hydrogen peroxide is also an ingredient in mouth washes to relieve minor mouth and gum irritations.
• A 1.5% solution can be used in gargles to treat acute mouth ulcers.
• H2O2 is thermodynamically unstable and decomposes to form water and oxygen: 2H2O2 → 2H2O + O2.
• In acidic solutions, Fe2+ is oxidized to Fe3+ : 2 Fe2+(aq) + H2O2 + 2 H+ 2 Fe3+ (aq) + 2 H2O
• In basic solution H2O2 will reduce kmno4 to prepare O2: 2 KMnO4 + 3H2O2 → 2 MnO2 + 2 KOH + 2H2O + 3O2
• It is prepared by the direct action of oxygen and hydrogen: 2H2 + O2 -> 2H2O2.
• Formed by the action of barium peroxide with sulphuric acid: BaO2 + H2SO4 ----> H2O2 + BaSO4.
• Can be generated from electrolysis of water: O2 + 2H+ +2e -> H2O2.
• Hydrogen peroxide is created through the oxidation of isopropyl alcohol: (CH3)2CHOH + O2--> (CH3)2CO +H2O2 by anthraquinole process

Ferrous gluconate (C₁₂H₂₄FeO₁₄)

• Ferrous gluconate is less irritating to the GIT than other hematinics.
• Is is a substitute when ferrous sulfate cannot be tolerated.
• It serves as an iron supplement and food additive, existing as the iron(II) salt of gluconic acid.
• It has two 6-carbon chains with 5 hydroxyl groups each, attached at carbon positions 2,3,4,5,6.
• The chains are linked by an Fe2+ ion, attracted to the carbon chains.
• Is soluble in hot water and glycerin.
• It is practically insoluble in ethanol.
• It decomposes upon heating
• Is stable under normal temperatures and pressures.
• The side effects include constipation, diarrhea, nausea, vomiting, heartburn, and stomach pain.
• Can cause dark-colored stools or urine; and temporary staining of the teeth
• It appears between brown to greenish yellow granular with the presence of a slight caramel odor.
• Its color depends on pH, being light yellow at pH 2, brown at pH 4.5, and green at pH 7.
• The iron rapidly oxidizes at higher pH levels.
• It is incompatible with strong oxidizers.
• The treatment targets low blood levels of iron and hypochromic anemia.
• Ferrous gluconate is also used during pregnancy.
• Is a color retention agent and stabilizer
• Used to enhance iron nutrition in grain products, beverages, baby foods, and candies.
• It is contraindicated in people with iron overload disorder, hemochromatosis, or hemosiderosis.
• It is contraindicated in people with certain medical conditions, people that regularly consume alcohol, have a liver problem, stomach or intestinal problem, or diabetes
• Chewable tablets may contain aspartame; restrict aspartame intake if a person has phenylketonuria (PKU) or any other condition.
• It should not be taken with milk, antacids, cereals, and grains, as these foods reduce the absorption of iron.

Boric acid (H₃BO₃)

• Boric acid is a weak acidic hydrate of boric oxide, its water soluble, and appears as an odorless, white crystalline solid.
• The mineral form is called sassolite.
• It is also known as ortho boric acid, boracic acid, trihydroxyborane and boron trihydroxide.
• It exhibits mild antiseptic, antifungal, and antiviral properties.
• It is generally cytotoxic to all cells.
• Boric acid is used in the treatment of yeast infections and cold sores.
• Boric acid and its salts are found in seawater and in plants, including almost all fruits.
• TThe toxicity of boric acid depends upon the amount of boron it contains.
• Boric acid solutions when used as an eyewash or on abraded skin are especially toxic to infants given their slow elimination rate.
• Long-term exposure can cause kidney damage and eventually kidney failure.
• Boric acid can be prepared by reacting borax (sodium tetraborate decahydrate) with HCl: Na₂B₄O₇⋅10H₂O + 2 HCl → 4 B(OH)₃ + 2 NaCl + 5 H₂O.
• It is also formed as a by-product of hydrolysis of boron trihalides and diborane: B₂H₆ + 6 H₂O → 2 B(OH)₃ + 6 H₂; BX₃ + 3 H₂O → B(OH)₃ + 3 HX (X = Cl, Br, I).
• Is an antiseptic for minor burns or cuts.
• It is sometimes used in dressings.
• It is applied in a very dilute solution as an eye wash.
• Dilute boric acid can be used as a vaginal douche to treat bacterial vaginosis due to excessive alkalinity.
• Serves as an anti-bacterial compound, which can also be used as an acne treatment.
• Prevents athlete's foot when inserted as a powder in socks or stockings.
• It is a treatment for otitis Externa.
• Used as a preservative in urine sample bottles.
• It serves as an insecticide and flame retardant and is a precursor to other chemical compounds.
• It was used for cleaning and preserving food in ancient times.
• It's a constituent of many naturally occurring minerals like borax and boracite.