Practice Paper 2 (HL IB Chemistry)

This question is about line emission spectra of elements.

The visible line emission spectrum of hydrogen is shown below in Figure 1 and the wavelengths of the first four lines are listed in Table 1.

Figure 1

The visible line emission spectrum hydrogen

 Table 1

Draw the shape of a 1s atomic orbital and 2p atomic orbital.    

Describe the relationship between colour, energy, frequency, and wavelength in the visible spectrum.

A compound with M_r =104.07 contains 34.62 % carbon, 3.88 % hydrogen and 61.50 % oxygen by mass. 

Calculate its empirical formula.

Calculate the molecular formula of the compound in part a).

Deduce the empirical formula of the following molecule:

The type of bonding and percentage ionic / covalent character of binary compounds can be deduced using triangular bonding diagrams.

Complete the table by calculating Σχ and Δχ for the given compounds.

Use section 9 of the data booklet.

Use data from sections 9 and 17 of the data booklet to percentage covalent character and bonding type in the following compounds:

Deduce the chemical that is found in the bottom left of a triangular bonding diagram by using sections 9 and 17 of the data booklet.

This question refers to the elements in the first three periods of the Periodic Table.

Select an element from the first three periods that fits each of the following descriptions.

[1]

[1]

[1]

This question is about the elements which have atomic numbers 33 to 37.

The first ionisation energies of these elements are shown in the table below.

[2]

[2]

[1]

The first 3 elements of Period 3 show a general increase in melting point.

Explain this trend in melting point across these Period 3 elements.

This question is about hydrogen, the element with the atomic number Z = 1.

Hydrogen can be placed in several different positions in periodic tables. One is immediately above lithium in Group 1 as shown in section 6 of the data booklet. Another is in the centre of the first row.

Evaluate the position of hydrogen when it is placed immediately above lithium and state one reason in favour and two against. 

Metals can often be seen written as a list, from the most reactive metal to the least reactive metal. This list is known as the reactivity series of metals and can be used to predict the feasibility of a reaction. 

Below is a section of the reactivity series of metals, ordered from most to least reactive: 

            Calcium

            Magnesium

            Aluminium

            Zinc

            Iron

            Tin

            Lead 

A piece of zinc was placed into a solution of iron(II) sulfate and a solution of magnesium sulfate.

Predict, giving a reason, whether a reaction would occur in each solution. 

Copper is below lead on the reactivity series shown in part (a). A piece of zinc was placed into a solution of copper(II) sulfate. Write the half equation for the zinc and identify the type of reaction taking place.

Many chemical reactions are redox reactions as they involve the transfer of electrons.

The following reaction is an example of a common redox reaction:

      5Fe²⁺ (aq) + MnO₄^- (aq) +8H⁺ (aq) → 5Fe³⁺ (aq) + Mn²⁺ (aq) + 4H₂O (l) 

Deduce the oxidation numbers of iron and manganese in the above reaction, both as reactants and as products.           

State which substance is reduced.

The amount of iron in some dietary iron supplements was analyzed by redox titration. Four tablets were crushed and dissolved in 50.0 cm³ of 2.00 mol dm^-3 sulfuric acid. The solution was then transferred to a 250 cm³ volumetric flask and made up to 250 cm³ with distilled water. 

A 25.0 cm³ sample of the iron tablets solution was titrated against 0.00500 mol dm^-3 potassium manganate(VII) and 25.8 cm³ was needed for complete reaction. 

Determine the amount of iron, in mol, in one tablet.

The enthalpy of solution of sodium chloride is +4 kJ mol^-1. Explain why the free energy change for dissolving sodium chloride in water is negative, despite the enthalpy change being a positive value.

Calcium carbonate thermally decomposes to form calcium oxide and carbon dioxide, as shown below:

CaCO₃ (s) → CaO (s) + CO₂ (g)

The enthalpy change of the above reaction is ΔH^Θ = +178 kJ mol^-1and the entropy change is ΔS^Θ = +161 J K^-1 mol^-1 

Calculate the temperature at which the free-energy change, ΔG^Θ, for this process is zero. 

Some ionic compounds such as potassium chloride, KCl, will dissolve in water at room temperature in an endothermic process. 

KCl (s) → K⁺ (aq) + Cl^- (aq)                ΔH = +16 kJ mol^-1

Diamond and graphite are both allotropes of carbon.

Dichloromethyl benzene reacts with chlorine to produce trichloromethyl benzene. State the name of this type of mechanism and the required condition. 

Outline the mechanism for the reaction occurring in part a).

A reaction pathway is shown below. Compound J reacts with bromine water to form a colourless solution.

State the IUPAC name for Compound J.

Benzene undergoes substitution reactions. State the equation for the reaction of benzene with nitric acid to produce nitrobenzene and water.

The structure of methylbenzene is shown below.

Draw the structures of the two isomers of choromethylbenzene formed from the reaction of methyl benzene and Cl₂ in the presence of AlCl₃. 

State the type of reaction that benzene will typically undergo.