Glucose, C₆H₁₂O₆, glyceraldehyde, C₃H₆O₃ and ethanoic acid, C₂H₄O₂ all have the empirical formula CH₂O. Glycerol, C₃H₈O₃ has the empirical formula C₃H₈O₃.

M_r CuSO₄.5H₂O = (64 + 32 + 64) + (5 x 18) = 250 so 125 g is 0.5 mol and contains 0.5 x 10 mol of H atoms = 3 x 10²⁴ H atoms.
6 g of H₂ contains 6 mol of H atoms = 3.6 x 10²⁴ H atoms; 23 g of ethanol (M_r = 46) is 0.5 mol so contains 0.5 x 6 mol of H atoms = 1.8 x 10²⁴ H atoms.  There are many moles of water in 5 dm³ of the HCl(aq) solution so the acid solution contains many more than 3 x 10²⁴ H atoms.

Amount of Zn = 6.5/65 = 0.1 mol. Zn(s) + H₂SO₄(aq)  → ZnSO₄(aq) + H₂(g) so amount of hydrogen produced = 0.1 mol. 1.0 mol of gas produced at STP (273 K,  1 x 10⁵ Pa ) occupies 22.7 dm³,  so volume of H₂ produced at 310 K = 0.1 x 22.7 x 310/273 dm³.

The visible series is produced by electrons transitioning from higher levels to the n = 2 level. The first line in the visible series is due to n = 3 to n = 2, the second line n = 4 to n = 2 and the third line from n = 5 to n = 2.

After the third electron has been removed the electron configuration of the ions will be B³⁺ 1s², Al³⁺ 1s²2s²2p⁶, Si³⁺ 1s²2s²2p⁶3s¹ and Sc³⁺ 1s²2s²2p⁶3s²3p⁶. Si will have the lowest fourth ionization energy as it has one electron in an outer energy level. The remaining three elements will all be high as they have completely full outer energy levels but boron will be the highest as the electron being removed is in the lowest energy level.

The atomic radius increases upon descending both groups. The first ionization energy and electronegativity both decrease upon descending both groups. Melting points decreases from Li to Cs but increase from F to I.

The electron configuration of Cu⁺ is [Ar]3d¹⁰. As it does not contain any unpaired electrons it will be diamagnetic. The other three ions all contain unpaired electrons so are paramagnetic.

The colour of transition metal complexes is due to light being absorbed as electrons are excited from a lower to a higher level in the split d sub-level. The colour that is observed is the complementary colour to the colour absorbed. Pink is the complementary colour to blue so the absorption occurring in [Mn(H₂O)₆}²⁺ is of higher energy/shorter wavelength than the absorption occurring in the red region of the spectrum in [Cu(H₂O)₆]²⁺.

The lead(II) ion is Pb²⁺ and the sulfate ion is SO₄²⁻.

There are only six electrons (three bonding pairs) around the boron atom in BCl₃. AlCl₃ also has an incomplete octet but when it dimerises to form Al₂Cl₆ coordinate bonds are formed between Cl and Al to complete the octet. The carbon atom in CHCl₃ has four bonding pairs of electrons and the phosphorus atom in PCl₃ contains three bonding and one non-bonding pairs of electrons.

Ozone is described by two resonance structure and the carbonate and nitrate ions are each described by three resonance structures. In aluminium chloride dimer all the bonds are single bonds so can be described by a single structure, .

In diamond all the carbon atoms are sp³ hybridized to give a tetrahedral structure and in graphite they are all sp² hybridized to give  layers made of hexagonal rings with bond angles of 120^o. In ethanenitrile the carbon atom bonded to the nitrogen atom is sp hybridized. In methylbenzene the six carbon atoms in the phenyl group are sp² hybridized and the methyl carbon atom is sp³ hybridized.

Ethanal contains six σ and one π bond. Propyne contains six σ and two π bonds. Ethene contains five σ and one π bond. Ethanoic acid contains seven σ and one π bond.

50.0 cm³ of 1.00 mol dm⁻³ hydrochloric acid, HCl(aq) contains 50.0/1000 = 0.05 mol so amount of heat evolved = 57.6 x 0.05 = 2.88 kJ. Total volume of solution = 100 cm³, so mass of solution = 0.100 kg.
ΔT = 2.88 ÷ (4.18 x 0.1) = 28.8 ÷ 4.18 ^oC 

Average bond enthalpies only refer to the gaseous state. To form gaseous prop-2-ene the bonds broken are C=C and H−Br so the energy in = 614 + 366 kJ. The bonds formed are C−Br, C−C and C−H so the energy out = − (285 + 346 + 414) kJ. The change in enthalpy = − [(285 + 346 + 414) − (614 + 366)] kJ. However the product is in the liquid state so a further 30 kJ of energy will be given out as the gas condenses to a liquid so ΔH = − [(285 + 346 + 414) − (614 + 366) + 30] kJ.

Hydration energy is the enthalpy change when molar quantities of gaseous ions dissolve in sufficient water to give an infinitely dilute solution. The process is highly exothermic. Generally the smaller and more highly charged the ions the greater the hydration energy.

B and C will have positive ΔS values as the amount in the gaseous state increases as the reaction proceeds whereas A and C will have negative ΔS values. ΔG = ΔH − TΔS so to be spontaneous at low temperatures (where TΔS is relatively small) ΔH needs to be negative and for it to be non-spontaneous at higher temperatures ΔS must be negative so that ΔH − TΔS has a positive value.

Although increasing the concentration of the reactants, increasing the pressure of gaseous reactants, increasing the temperature and decreasing the particle size (i.e. increasing the surface area) of solid reactants all increase the rate of the reaction they do this by either increasing the number of collisions or by increasing the energy of the particles so that more possess the minimum energy required to react. The addition of a suitable catalyst changes the reaction pathway to one with a lower activation energy.

The temperature of the solution, volume of gas  evolved and mass of remaining reactants as the carbon dioxide evolves all change over time. There is no change in colour over time as the white calcium carbonate solid dissolves in colourless hydrochloric acid to give a colourless solution.

The rate at which the concentration of A decreases over time will be constant for a zero order reaction, so a graph of [A] against time will be a straight line with a negative slope. D is the graph for a second order reaction and A and B are both for first order reactions.

For the mechanism to be consistent with the rate equation the rate equation must be rate = k[NO(g)]²[H₂(g)] so the overall order is three. The units of the rate constant will be dm⁶ mol⁻² s⁻¹ and the molecularity of the rate determining step (the second step) will be two..

K_c is a constant at a specified temperature so altering the pressure has no effect on the value of K_c. The reaction is exothermic as ΔH has a negative value so lowering the temperature will shift the position of equilibrium towards the products and increase the value of the equilibrium constant.

The entropy will have a maximum value at equilibrium so that the available energy is distributed in as many ways as possible.  At equilibrium ΔG = 0. This is because the rate of the forward reaction is equal to the rate of the reverse reaction so no net reaction occurs hence ΔG will be zero.

The conjugate base is formed when a proton is donated, OH⁻(aq) → H⁺(aq) + O²⁻(aq)

Strong acids are completely dissociated into ions so have a higher electrical conductivity than weak acids which are only partially dissociated. [H+(aq)] will be higher for strong acids so the pH will be lower.

pK_a = − log₁₀K_a. The smallest value for K_a (in the order of 10⁻⁶ so smaller than C₆H₅COOH which is in the order of 10⁻⁵) is for (CH₃)₃CCOOH. The K_a of HCOOH is in the order of 10⁻⁴ so the largest value for K_a (in the order of 10⁻³) is for CH₂ClCOOH.

NaNO₃ is the salt of a strong acid and a strong base so will give a neutral solution. NH₄CH₃COO is the salt of a weak acid and a weak base so will also give a solution with a pH of approximately 7 (the exact pH depends upon which of the two dissociates the most). NH₄NO₃ is the salt of a strong acid and a weak base so will give an acidic solution with a pH less than 7, whereas Na₂CO₃ is the salt of a strong base and a weak acid so will give an alkaline solution with a pH greater than 7.

H has an oxidation state of +1 (except for hydride ions, H⁻ where it is −1 ) and O has an oxidation state of −2 (except for peroxides −O−O− where it is −1) so iodine must have an oxidation state of +5 in iodic acid to give the sum of the oxidation states equal to zero. In hypoiodous acid the oxidation state of iodine is +1, in iodine dioxide it is +4 and in orthoperiodic acid it is +7.

When hydrogen peroxide decomposes it simultaneously oxidises and reduces itself so that the oxidation state of oxygen in hydrogen peroxide (+1) increases to zero in oxygen and decreases to minus two in water (this is an example of disproportionation). When it acts as a reducing agent, as with KMnO₄ and NaOCl, oxygen is formed and when it acts as an oxidising agent, as with FeSO₄, it is reduced to water.

For every two mol of H₂ evolved at the cathode 1 mol of O₂ will be evolved at the anode. By Avogadro's Law the ratio of the volumes will be the same as the molar ratio. If the current is tripled and the time is halved the amount of H₂ evolved will be increased 1.5 times to 60 cm³. Hence the volume of O₂ evolved will be 30 cm³.

The spontaneous reaction that occurs is Ni(s) + Cu²⁺(aq) → Ni²⁺(aq) + Cu(s) with an EMF of 0.60 V (where 0.60 V is the difference between the two E^⦵ values for the two half-cells). ΔG = − nFE^⦵ = − 2 x 9.65 x 10⁴ x 0.60 J mol⁻¹.

A tertiary carbon atoms is bonded to a functional group such as a halogen or -OH and to three R groups (the R groups may be the same as each other or different). A tertiary carbon atom is not bonded to a hydrogen atom.

>C=O, >C=C< and −OH (carbonyl, alkenyl and hydroxyl) are all present. −CHO, C₆H₅− and R−O−R' (aldehyde, phenyl and ether) are all absent.

In the presence of a sulfuric acid catalyst, carboxylic acids condense with alcohols to form an ester and water.
CH₃CH₂COOH + CH₃CH(OH)CH₃ → CH₃CH₂COOCH(CH₃)₂ + H₂O

Hydrogen bromide is polar, ^δ+H−Br^δ−. The mechanism is electrophilic addition. The hydrogen atom adds to the carbon atom that already contains the most hydrogen atoms bonded to it. This is because the tertiary carbocation that is formed is more stable than the primary carbocation that would be formed if it added to the other carbon atom making up the double bond.

Both conformational and configurational isomerism are forms of stereoisomerism. Conformational isomerism involves rotations about single bonds  whereas the rotations in configurational isomerism involve the breaking and reforming of chemical bonds. Butane can be rotated about the single bond between the second and third carbon atoms.

Chlorine has a higher atomic number than carbon so has a higher priority according to Cahn-Ingold-Prelog (CIP) rules. In both cases the two highest groups are on the same side so both isomers have the Z configuration.

The number of significant figures in a result is based on the figures given in the data. Since the concentration of the potassium hydroxide solution is only given to two significant figures the concentration of the hydrochloric acid solution should only be quoted to two significant figures.

When determining IHD, O atoms count as zero. For each N atom add one to the number of C atoms and add one to the number of H atoms. This gives the equivalent of C₇H₈ which needs 8 more hydrogen atoms (4 units of H₂) to become saturated as C₇H₁₆, hence the IHD is 4. 

Butan-1-ol, CH₃CH₂CH₂CH₂OH and butan-2-ol, CH₃CH₂CH(OH)CH₃ will both give five signals as the hydrogen atoms in both compounds are in five separate chemical environments. Butan-1-ol will have the ratio of 3:2:2:2:1 and butan-2-ol will have the ratio 3:2:1:1:3 for the areas under each signal. Because butan-2-ol contains one carbon atom bonded to only one hydrogen atom their splitting patterns will be different. Since the oxygen atom is on a different carbon atom their chemical shifts will also be different.