Doublemm's Disastrous Interview! Quiz

Answer: Chlorofluorocarbons' action on ozone

A free radical is any atom, ion or molecule which has an unpaired electron. The property of having unpaired electrons makes free radicals highly chemically reactive.

CFCs are chlorofluorocarbons and they contain at least one atom of carbon, chlorine, and fluorine.

The problems these pose to the ozone layer start as the gases begin to rise up into the upper levels of the atmosphere. At higher levels, sunlight provides enough energy to break a covalent bond which holds together a carbon atom and a chlorine atom. This bond breaks homolytically, meaning that each atom gains one electron which was previously part of the covalent bond. Therefore, the breaking of one of these covalent bonds produces two free radicals. Carbon to chlorine bonds tend to break more readily than carbon to fluorine bonds, as fluorine has a higher charge density than chlorine and so can form stronger covalent bonds.

The free radicals produced in this first step then enter a series of reactions which collectively convert ozone (O3) into oxygen gas (O2).

Other examples of free radical substitution include the initiation step of the halogenation of alkanes and the polymerisation of alkenes.

Answer: No

No, no, definitely not! The product of this reaction using this technique is generally 95% ethanol by volume. Whilst this is likely to make you rather ill if you drink it, it is particularly useful as a solvent. The ethene here is usually made by cracking hydrocarbons obtained from crude oil.

Ethanol for alcoholic drinks is often produced by the fermentation of glucose. This usually involves a heat of 37 Celsius and the presence of the enzyme, zymase (present in yeast). The product here is usually 7-15% ethanol by volume as zymase is denatured at ethanol concentrations above 15%.

Answer: The specific heat capacity of the reactant

The enthalpy of something is its total energy content. The total energy content of a glass of water, for example, is due to the room temperature, the movement of its molecules, and the energy stored in its bonds.

Although it is not possible to measure the enthalpy of a substance, it is possible to measure the enthalpy *change* during a reaction. This is done by taking measurements on a thermometer and using the equation above.

Answer: Argon, which although being a noble *gas* is usually liquid at room temperature

Zinc, although found in the transition metal section of the periodic table, is not technically a transition metal.

The Aufbau principle is that the sub-shells of an atom will be filled in a certain order (1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10 etc) and that each sub-shell must be filled before electrons can enter the next sub-shell in the sequence. Copper, however, has a half-full 4s sub-shell whilst having a full 3d sub-shell (the Aufbau principle states the 4s sub-shell should be filled before the 3d sub-shell).

Aluminium chloride should be an ionic compound as Al is a metal and Cl is a non-metal. However, this compound is covalent.

Answer: It increases

The reason for this is that melting/boiling points here are determined by Van der Waals' forces between diatomic molecules. As we move down the group, the number of electrons in the atom increases and so there is a higher chance of an uneven distribution of electrons and so there are more/stronger Van der Waals' forces which form.

This means that more energy is needed to overcome these forces.

Answer: Both are lone pair donors

A lone pair is a pair of electrons not involved in bonding.

Nucleophiles are attracted to positive centres. A positive centre is caused when a less electronegative atom (e.g. carbon) is attracted to a more electronegative atom (e.g. bromine). The presence of a nucleophile often causes the bond between the more electronegative atom and the less electronegative atom to break. Nucleophiles include water, hydroxide ions and ammonia.

Bases are defined as hydrogen ion acceptors. What allows bases to "accept" a hydrogen ion is their lone pair, which forms a dative covalent bond - a covalent bond where the both of the bonding electrons are provided by only one of the bonding atoms.

Answer: Phosphoric acid

Hydration means adding water. Phosphoric acid is often used as the catalyst in converting an alkene into an alcohol. This reaction also requires 300 degrees Celsius and 60 atm of pressure.

Hydrogenation converts an alkene into an alkane. It requires a nickel catalyst, 100 degrees Celsius and 4 atm of pressure.

Sulphuric acid is used as the catalyst in many reactions. One example is during the dehydration reaction where an alcohol is converted into an alkene.

Iron is used in the Haber process, which convert hydrogen and nitrogen into ammonia. The conditions of the Haber process are typically 450 degress Celsius and 100 atm of pressure.

Other catalysts include palladium, used in catalytic converters, aluminium oxide, used in cracking alkanes, and platinum which is used in reforming alkanes.

Answer: Carbons 2, 4 and 6

A benzene ring joined to one hydroxyl group is known as phenol. The hydroxyl group (or phenol group) is said to be 2, 4, 6 inducing. With two lone pairs on the oxygen, the hydroxyl group literally pushes negative charge onto the benzene ring and is said to "activate" it.

The negative charge is particularly high at carbons 2, 4 and 6 and so these tend to react with electrophiles before the other carbons in benzene.

Answer: Electrophilic addition

An electrophile is a lone pair acceptor and so is the opposite of a nucleophile (a lone pair donor). The reason that they react with alkenes is because the carbon to carbon double bond is a centre of electron density.

In the presence of the carbon to carbon double bond, the covalent bond between the two bromine atoms breaks heterolytically (both bonding electrons go to just one of the bonding atoms). The pair of electrons present in the pi bond of the carbon to carbon double bond are then used up in a dative covalent bond with the positive bromonium ion. The negative bromide ion then uses its lone pair to datively bond with the other carbon atom which was involved in the carbon to carbon double bond.

The result of this is the brown bromine water turning clear.

Answer: Lithium aluminium hydride

If you wanted to show off you could also offer sodium boron hydride as an option for reducing a ketone to an alcohol. The alcohol which is formed by this process is a secondary alcohol, whereas a primary alcohol is formed from the reduction of an aldehyde (or caboxylic acid).

Potassium dichromate (VI) is an oxidising agent, which has an opposite effect to reducing agents (i.e. they oxidise alcohols into ketones/aldehydes/carboxylic acids). The sign that oxidation has taken place is the orange potassium dichromate (VI) becoming green.

Tollen's reagent (ammoniacal silver nitrate) is another oxidising agent, albeit a weaker one, and is used to oxidise an aldehyde to a ketone.

Trinitrotoluene is more commonly known as TNT.