Category: A-Level Chemistry
Reaction of phosphorus with concentrated acid
Phosphorus gets oxidised to phosphoric acid according to the following reaction 2P+5H2SO4→2H3PO4+2H2O+5SO2. Read More
A solution of sodium thiosulphate become cloudy with the formation of a yellow precipitate when left in air. Explain.
carbon dioxide dissolve in water to form carbonic acid; the acid hydrolyzes thiosulphate to yellow sulphur S2O32- (aq) + 2H+ (aq) → H2O (l) + ... Read More
Sodium chloride melts at 8000C whereas aluminium chloride sublimes at 1800C Explain
Sodium chloride melts at 8000C whereas aluminium chloride sublimes at 1800C. Explain Sodium ions have low charge density compared aluminium ions Thus sodium ions weakly ... Read More
How the stability of the oxidation states of group IV element vary down the group. (Illustrate your answer with the chloride of carbon and lead)
Oxidation state +2 become more stable down the group Oxidation state +4 become less stable down the group. This can be illustrated by chlorides of ... Read More
The acidity of halogens acids decrease in the order HI>HBr>HCl although their ionic characters increase in the reverse order.
In other solvents, however, the strengths of these acids decrease in the order HI > HBr > HCl: due to the decrease in the H-X ... Read More
When sodium carbonate solution was added to 2,4,6 – trinitrophenol solution effervescence of a colorless gas occurs whereas when sodium carbonate solution was added to phenol, there is no observable change. Explain.
2,4,6 – trinitrophenol iberated carbon dioxide from sodium carbonate while phenol does not because 2,4,6 – trinitrophenol contains electron withdrawing groups (nitro groups); these withdraw ... Read More
e. Ice is less dense than water.
The hydrogen bonds in water ice are indeed strong, but their orientation causes molecules to push apart leading to an open structure of a bigger ... Read More
The boiling point of ethanol is higher than that of ethane.
Ethanol forms intermolecular hydrogen bond that require high temperature to break whereas ethane form weak molecular forces Read More
Magnesium readily reacts with concentrated nitric acid whereas beryllium does not react with concentrated nitric acid. explain
Beryllium forms an impervious layer of oxide which prevents further reaction whereas magnesium is an electropositive element that reacts readily with nitric acid Read More
Explain why the boiling points of ethanol solution is lower than that of water and pure ethano
In solution of ethanol the forces of attraction between unlike molecules are weaker than those of like molecules this leads to high tendency to evaporate ... Read More
Explain why the boiling point of a hydrochloric acid solution is higher than that water and pure hydrogen chloride
Hydrochloric acid solution undergoes negative deviation because hydrogen bonds between water hydrogen chloride molecules are stronger than those between like molecules. This reduces evaporation tendency ... Read More
Explain why lattice energy of magnesium oxide (MgO) is higher than that of magnesium chloride (MgCl2)
Magnesium oxide has high lattice energy because Magnesium ions and oxygen ion are bonded by a double bond that is stronger than a single bond ... Read More
Explain why lattice energy of lithium fluoride (LiF) is higher than that of sodium fluoride (NaF)
LiF and NaF have the same charge product, as lithium and sodium are both 1+ and fluorine is 1-. The fluorine radius will be the ... Read More
Explain why distilled water is preferred to dilute sulphuric acid when changing an accumulator cell.
During recharging, there can be some production of hydrogen and oxygen caused by splitting of the water part of the acid. This needs to be ... Read More
Explain why carbon reacts with fluorine but not with chlorine
Fluorine is a stronger oxidizing agent than chlorine, has very low F-F bond energy and form stronger C-F bond the C-Cl bond, these factors promote ... Read More
Reaction of Silicon with acids
Silicon does not react with most acids under normal conditions but is dissolved by hydrofluoric acid, HF, to form fluorosilicic acid, a reaction apparently driven ... Read More
Reaction of lead (IV) oxide with sodium hydroxide solution
The compound PbO2 reacts with the sodium hydroxide to produce the hexahydroxoplumbate (IV) ion <Pb(OH)6>2−, soluble with the water. PbO2 + 2NaOH + 2 H2O → Na2<Pb(OH)6> Read More
Reaction of Lead(IV) chloride with sodium hydroxide
Lead(IV) chloride react with sodium hydroxide to produce lead(IV) oxide, sodium chloride and water. Sodium hydroxide - diluted solution. PbCl4 + 4NaOH → PbO2 + 4NaCl + ... Read More
Reaction of lead II chloride with sodium hydroxide solution
Lead II chloride reacts with sodium hydroxide solution to form lead (II) hydroxide which dissolves in excess sodium hydroxide to form sodium plumbate (II) PbCl2 ... Read More
Effect of heat on hydrate iron II sulphate pentahydrate
On heating, iron(II) sulfate first loses its water of crystallization and the original green crystals are converted into a white anhydrous solid. FeSO4.7H2O(s) → FeSO4(s) ... Read More
Effect of heat on copper sulphate pentahydrate
On heating (2000C) copper sulphate pentahydrate loses it loses water of hydration and turn from blue crystal to white powder CuSO4.5H2O(s) → CuSO4(s) + 5H2O(l) ... Read More
Aldol condensations of carbonyl compounds
Aldol condensations of carbonyl compounds Carbonyl compounds which contain at least one alpha hydrogen, react in presence of alkali to form hydroxyl carbonyl compounds called ... Read More
Cannizzaro reaction of aldehydes
Cannizzaro reaction of aldehydes This is a reaction between sodium hydroxide solution and aldehydes with no α-hydrogen It’s a self-oxidation – reduction reaction Examples Please ... Read More
Distinguishing between aldehydes and ketone
Reagent Observation Aldehydes Ketones Fehling’s solution Brown ppt No observable change Tollen’s reagent or ammoniacal silver nitrate Black ppt or silver mirror No ... Read More
Reaction methyl ketone with iodine
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Reaction of benzene with chlorine in the presence of u.v-light
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Reaction of benzene with alkenes
Reaction of benzene with alkenes In the presence of a mineral acid benzene react with alkenes to form alkylbenzene. Please Subscribe to promote this website. ... Read More
Reaction of benzene with alkanoylhalides
The reaction requires an electron carrier and produces ketones Example Please Subscribe to promote this website. Subscription is free Share with a friend Your comment ... Read More
Reaction of benzene with alkyl halides like chloromethane
This is a reaction of benzene with an alkyl halide to give an alkyl benzene. The reaction is catalysed by electron carriers such as ... Read More
Reaction of benzene with halogens, chlorine, bromine, iodine
Reaction of benzene with halogens This requires the use of electron carriers (AlCl3, FCl3) as catalysts. The electron carrier is usually a halide of iron ... Read More
Sulphonation of benzene or reaction of benzene with sulphuric acid
Sulphonation of benzene is the introduction of the sulphonic group (-SO3H) on to the benzene ring. It’s done by heating benzene with concentrated suphuric acid. A ... Read More
Nitration of benzene or reaction of benzene with nitric acid
Nitration of benzene This is the introduction of the nitro group on the benzene ring using a hot mixture of concentrated sulphuric acid and concentrated ... Read More
Preparation of phenol form cumene or 2-phenylpropane
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Distinguishing between primary, secondary and tertiary amines
Distinguishing between primary, secondary and tertiary amines Reagent: nitrous acid (NaNO2, HCl (0-50C)) Observation (i) Primary amine: effervescence Equation RNH2 + NaNO2 + 2HCl ... Read More
Explain why phenylamine is a weaker base than ammonia and ammonia is a weaker base than dimethylamine
Solution Trimethylamine is a stronger base than ammonia because the methyl groups donate electrons to the nitrogen atom. This increases the density of alone pair ... Read More
Basic trendsof amines
Bacisity of amines Like ammonia, amines dissolve in water to form alkaline solution. RNH2 + H2O ↔ RN+H3 + OH-(aq) The strength of ... Read More
Variation of boiling and melting points of amines
Variation of boiling and melting points of amines Amines are polar compounds and therefore have higher melting and boiling points than non-polar compounds of similar ... Read More
Reaction of terminal alkyne with ammoniacal silver nitrate or copper 1 nitrate
Alkynes with a triple bond at the end of the chain react with ammoniacal silver nitrate or ammoniacal copper I chloride to form white precipitate ... Read More
Reaction of ethyne with water
The reaction ethyne with water is catalysed by mercury (II) sulphate and dilute sulphuric acid. Carbonyl compounds are formed. Example Mechanism Please Subscribe to promote ... Read More
Reduction of alkynes
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Preparation of ethyne from ethanol
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Preparation of ethyne from 1, 2-dibromoethane
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Preparation of ethyne from carbon
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Preparation of alkenes from tertiary alkyl halides
Tertiary alkylhalides in presence of hot solution of excess alcohol and potassium hydroxide undergo elimination reaction to form alkenes. The mechanism is described as E1 ... Read More
Preparation of alkenes from primary alkyl halides
Preparation of alkenes from primary alkyl halides Primary alkyl halide react with hot solution of excess alcohol and potassium hydroxide to form alkenes. the mechanism ... Read More
Preparation of alkenes from tertiary alcohols
Preparation of alkenes from tertiary alcohols Tertiary alcohols react with hot concentrated sulphuric or phosphoric acid to give alkenes. The mechanism is described as E1 ... Read More
Preparation of alkenes from primary alcohols
Primary alcohol react with hot concentrated sulphuric or phosphoric acid to form alkenes. The mechanism is referred to as elimination bimolecular(E2) because water molecule is ... Read More
Polymerization of dienes
Polymerization of dienes Alkenes with conjugated double bond undergo polymerization to form polyalkenes with double bonds Example Please Subscribe to promote this website. Subscription is ... Read More
Ozonolysis (reaction of ozone with alkenes)
Ozonolysis (reaction of ozone with alkenes) Ozone reacts with alkene to form unstable ozonide that is reduced by zinc in presence of hydrochloric acid to ... Read More
Reaction of alkenes with hydrogen bromide in presence of a peroxide
Reaction of alkenes with hydrogen bromide in presence of a peroxide In presence of a peroxide, alkenes react with HBr by free radial mechanisms; but ... Read More
Reaction of alkene with water
Reaction of alkene with water. The reaction is catalyzed by an acid sulphuric acid or phosphoric acid. Alcohols are produced Example 1 Ethene reacts with ... Read More
Reaction of alkenes with halogens in presence of water.
Reaction of alkenes with halogens in presence of water. The reaction is carried out by bubbling alkenes through aqueous halogens. Example Propene reacts with chlorine ... Read More
Reaction of alkenes with hydrogen halides (HX ; X = Cl, Br, I)
Reaction of alkenes with hydrogen halides (HX ; X = Cl, Br, I) The reaction is carried out by bubbling HX through alkenes. Example 1 ... Read More
Reaction of alkenes with halogens
Reaction of alkenes with halogens Halogens add across a double bond to form dihalogeno compounds. The reaction is carried out in an inert solvent like ... Read More
Reaction of alkenes with alkaline KMnO4 (potassium manganate) (VII) solution
Reaction of alkenes with alkaline KMnO4 solution Dilute alkaline KMnO4 solution convert alkenes into compound called GLYCOLS (dihydroxyl alcohols) Please Subscribe to promote this website. ... Read More
Reduction of alkenes
Reduction of alkenes They are reduced by hydrogen in presence of catalysts; nickel or platnum to alkenes Example Please Subscribe to promote this website. Subscription ... Read More
Rules for naming alkanes or nomenclature of alkanes
(a) Names of straight chain isomers alkanes Straight chain isomers are named according to the number of carbon atoms in the chain. (a) Naming branched ... Read More
What is alkyl groups?
An alkyl group is an alkane less one hydrogen atom. Examples CH4 Methane CH3- methyl group CH3CH3 Ethyl ... Read More
Names of first ten straight chain alkanes
Names of first ten straight chain alkanes Please Subscribe to promote this website. Subscription is free Share with a friend Your comment is valuable Thank ... Read More
Types of Isomerism in organic chemistry
Types of isomerism Structural isomerism Optical isomerism Structural isomerism Here compounds differ in arrangement of atoms in a compound. (a) Chain isomerism: compound have the ... Read More