MyChemistryHomework

Chemists must make use of science with safety and conscience . Chemistry should be part of history to unfold the mystery of molecules being wary. Methanol poisoning, which may be accidental or as part of an attempted suicide, most commonly occurs following the drinking of tainted alcoholic beverages made with windshield washer fluid, and may rarely occur through extensive skin exposure or breathing in fumes. Ethylene glycol poisoning may also be accidental ( viz. , from antifreeze) or as part of an attempted suicide. Ethylene glycol is more toxic than other diols. Diethylene glycol ( DEG ) is a widely used solvent. It can be a normal ingredient in various consumer products, or a contaminant. DEG has also been misused to sweeten wine and beer, and to viscosity oral and topical pharmaceutical products. Its use has resulted in many epidemics of poisoning since the early 20th century. The allowed limit in medications like cough syrups in India and by the WHO (world health organization) ...

The order of reaction is a number which quantifies the degree to which the rate of a chemical reaction depends on concentrations of the reactants. In other words, the order of reaction is the exponent to which the concentration of a particular reactant is raised. One could write the rate equations for the given sets of data and solve for the orders w.r.t. the reactants. Question: The reaction between Nitric oxide and Bromine is represented below. The proposed reaction mechanism is as follows: NO + Br 2 ⇌ NOBr 2 (fast) NOBr 2 + NO → 2NOBr (slow) What is the overall order of the reaction consistent with the proposed mechanism? Solution: Click/tap to enlarge the image k = Rate constant, K = Equilibrium constant It is difficult to determine the rate law from a reaction mechanism in which an intermediate ( NOBr 2 , in this case) is involved in the slow (rate determining) step. Ordeal with orders ❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail...

pH is a logarithmic scale used to specify the acidity or basicity of aqueous solutions. Acidic solutions (with higher concentrations of hydrogen ( H + ) cations) are measured to have lower pH values than basic or alkaline solutions. The neutral pH is 7 . A 𝑝𝐻 meter may be used for a precise and accurate measurement of the 𝑝𝐻 of a solution. When two or more solutions are mixed, one must add the volumes of all solutions. Question: A sample of 200 mL of 0.20 M Sr(OH) 2 is added to 800 mL of 0.80 M Ba(OH) 2 . What is the value that best approximates the pH of the final solution? Solution: Click/tap to enlarge the image NOTE: A strong base is completely ionized; and therefore, the molar concentration is equal to the [OH ─ ] . Want to estimate the pH of a very dilute solution of an acid? Click HERE . Want to estimate the pH of a weak base? Click HERE . Striking stoichiometry❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com ❗ Reference: ‌Brow...

An epoxide or oxirane is a triangular cyclic ether, a structure that has substantial ring strain, making epoxides highly reactive, more so than other ethers. An attack by a variety of nucleophiles gives multiple products. Wheel of Epoxides: Click/tap to enlarge the image Reaction type -> Product (on the infographic ): Deoxygenation -> Alkene Hydrolysis -> Glycol Solvolysis ->  β ─alkoxy alcohol (Hydrohalic acid) -> Halohydrin 1. Reduction ( LAH ) 2. Hydrolysis -> Alcohol 1. Reduction (LiAlD 4 ) 2. Hydrolysis ->  β ─ Deuterated alcohol 1. Hydroboration or (AlD 3 ) 2. Hydrolysis ->  Alcohol or  β ─ Deuterated alcohol 1. Reduction ( DIBAL ) 2. Hydrolysis -> Alcohol Grignard reaction or (1. Phenyl lithium 2. Hydrolysis) ->  β ─ Aryl alcohol Grignard or  Gilman reaction  -> β ─ Alkyl alcohol 1. (Lithiated 1,3-dithiane) 2. Hydrolysis ->  β ─(1,3-Dithianyl)  alcohol Grignard reaction ->...

Solubility equilibrium is a type of dynamic equilibrium that exists when a solid chemical compound is in chemical equilibrium with a solution of that compound. The solid may dissolve unchanged, with dissociation, or with chemical reaction with another component of the solution, viz. , acid, base or salt. Each solubility equilibrium is characterized by a temperature-dependent solubility product which functions like an equilibrium constant. Question: BaF 2 is sparingly soluble in water. What happens when dilute HF is added to a saturated BaF 2 solution at equilibrium? Solution: Click/tap to enlarge the image Negotiation on precipitation❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com ❗ References: (1)      Wikipedia Contributors. Solubility equilibrium . Wikipedia. https://en.wikipedia.org/wiki/Solubility_equilibrium. ‌ (2)      Ncert. Chemistry : Textbook for Class XI - Part.I ; National Council Of Educational Resea...

Redox or reduction–oxidation or oxidation–reduction (simultaneous) is a type of chemical reaction in which the oxidation states ( OSs ) of the reactants change. Mnemonic : OIL RIG ( O xidation I s L oss, R eduction I s G ain) Redox potential aka oxidation/reduction potential ( ORP or E red ) is a measure of the tendency of a chemical species to gain electrons from or lose electrons to an electrode; and therefore, be reduced or oxidized respectively. As per the IUPAC (international union of pure and applied chemistry), standard electrode potential ( E Ѳ ) is the value of the standard emf (electromotive force) of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode. Question: For the first-row transition metals the  E Ѳ  values are: E 0 (V) V Cr Mn Fe Co Ni Cu (M 2+ /M) –1.18 – 0.91 –1.18 – 0...

Phenols and its derivatives are chemically and biologically important. Redox of phenols has been studied in biological systems. Phenols change color on oxidation. Question: Predict the major product(s) of the following reactions: Click/tap to enlarge the image Solution infographic: Click/tap to enlarge the image L -DOPA = L -3,4-Dihydroxyphenylalanine, MDMA = 3,4-Methylenedioxymethamphetamine, SET = Single electron transfer Phenomenal phenols❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com ❗ References: (1)      Brown, C.; Ford, M. Higher Level Chemistry , 2nd ed.; Pearson Education: Harlow, Essex, 2014. (2)      Ncert. Chemistry : Textbook for Class XII - Part.II ; National Council Of Educational Research And Training: New Delhi. (3)      Graham, T. W.; Fryhle, C. B.; Snyder, S. A. Organic Chemistry. ; Hoboken, Nj John Wiley Et Sons, Inc, 2016. (4)     LibreTexts CHEMISTRY

Stoichiometry is the relationship between the quantities of reactants and products before, during, and after chemical reactions. A chemical equation is the representation of a chemical reaction in the form of symbols and chemical formulas. The coefficients next to the symbols and formulas of entities are the absolute values of the stoichiometric numbers. The limiting reagent ( aka limiting reactant/agent) in a chemical reaction is a reactant totally consumed when the chemical reaction is completed. Checking the limiting reactant ( LR ): To take the number of moles of each reactant and divide it by its stoichiometric coefficient in the balanced equation. The quotient with a lower value indicates the  LR . When two or more solutions are mixed, one must add the volumes of all solutions. Question: What is the final concentration of Pb 2+ ions when a 100 mL 0.20 M Pb(NO 3 ) 2 solution is mixed with a 100 mL 0.30 M NaCl solution? Solution: Click/tap to enlarge the image ...

An organic reaction in which an atom attached to an aromatic system (usually hydrogen) is substituted by an electrophile is referred to as electrophilic aromatic substitution ( S E Ar or EAS ). Direct or indirect introduction of functional groups to the benzene ring is possible by the EAS . Wheel of Electrophilic Aromatic Substitutions: Click/tap to enlarge the image Reaction type -> Product (on the infographic ): Bromination -> Bromobenzene Chlorination -> Chlorobenzene Iodination -> Iodobenzene Nitration -> Nitrobenzene Amination -> Aniline (multistep: 1. Nitration 2. Reduction) Methylation ( Friedel-Crafts alkylation ) -> Toluene Friedel-Crafts alkylation -> Cumene Friedel-Crafts acylation -> Propiophenone Alkylation -> n -Propylbenzene (multistep: 1. Friedel-Crafts acylation 2. Clemmensen reduction ) Friedel-Crafts alkylation -> t -Butylbezne Friedel-Crafts acylation -> Benzophenone Friedel-Crafts acylation -> 3-Benzoylpropion...

A reducing agent or an oxidizing agent may or may not be selective in an organic reaction. One of the options may be to choose a reagent that selectively attacks the desired functional group, but that may not be the case all the time. Question: How would you carry out the following transformations? Click/tap to enlarge the image Solution infographic: Click/tap to enlarge the image One might keep the carbonyl group untouched by using a selective reducing agent. Click HERE to find it out! Penchant for protection/deprotection❓ Let Chemaficionado know in the comments below or at mychemistryhomework@gmail.com ❗ References: (1)      Brown, C.; Ford, M. Higher Level Chemistry , 2nd ed.; Pearson Education: Harlow, Essex, 2014. (2)      Ncert. Chemistry : Textbook for Class XII - Part.II ; National Council Of Educational Research And Training: New Delhi. (3)      Graham, T. W.; Fryhle, C. B.; Snyder, S. A. Organic Chemistry. ; Hoboken, Nj...

Redox or reduction–oxidation or oxidation–reduction (simultaneous) is a type of chemical reaction in which the oxidation states ( OSs ) of the reactants change. Mnemonic : OIL RIG ( O xidation I s L oss, R eduction I s G ain) Redox potential aka oxidation/reduction potential ( ORP or E red ) is a measure of the tendency of a chemical species to gain electrons from or lose electrons to an electrode; and therefore, be reduced or oxidized respectively. As per the IUPAC (international union of pure and applied chemistry), standard electrode potential ( E Ѳ ) is the value of the standard emf (electromotive force) of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode. Question: Why is the E Ѳ  value for the Mn 3+ /Mn 2+ couple much more positive than that for Cr 3+ /Cr 2+ or Fe 3+ /Fe 2+ ? Solution: Click/tap to enlarge the image Ionization energy/enthalpy/potential ( IE ) is the minimum energy required to remove th...

Henry's law , a gas law, states that the amount of dissolved gas in a liquid is directly proportional at equilibrium to its partial pressure above the liquid. The depth-dependent dissolution of Oxygen and Nitrogen in the blood of underwater divers which changes during decompression, possibly causing decompression sickness if the decompression occurs too fast, is an application of Henry’s law. Scuba divers must handle high concentrations of dissolved gases in blood while breathing air at high pressure underwater. When the divers come toward the surface, the pressure gradually drops, which releases the dissolved gases as per Henry’s law forming bubbles of Nitrogen in the blood, which, in turn, blocks capillaries and gives rise to a medical condition referred to as bends, which is painful and may jeopardize life. The tanks used by scuba divers are filled with air diluted with Helium to avoid bends and the toxic effects of high concentrations of Nitrogen in the blood. Once the bottle o...

The electron configuration ( EC ) is the distribution of electrons of an atom, ion, or molecule in atomic or molecular orbitals. The  EC can be written using Aufbau principle , Pauli exclusion principle and Hund’s rule of maximum multiplicity . For the naming of elements of atomic numbers greater than 100 , IUPAC (international union of pure and applied chemistry) nomenclature may be used. Question: Which period/group would you place the elements in with Z = 116 & 120 ? Solution: Click/tap to enlarge the image The actinoid elements Ac-Lr (atomic numbers 89-103 ) have 5f -orbitals except Actinium and Thorium. The lanthanoid elements La-Lu (atomic numbers 57-71 ) have 4f -orbitals except Lanthanum. The maximum value of the principal quantum number in the EC is the period and the total number of valence shell electrons is the group (the ultimate digit). Element with Z = 116 is known as Livermorium ( Lv ) and with Z = 118 as Oganesson ( Og ). Engrossed in electron conf...