Synoptic Exam Questions (Paper 2) (DP IB Chemistry: SL): Exam Questions

The Periodic Table displays the chemical elements, arranged in order of increasing atomic number. It is made up of groups and periods of elements.

State and explain the general trend in first ionisation energy across a period of the Periodic Table.

State why nitrogen is classed as a p block element and give its full electron configuration.

Identify the Period 3 element that has the lowest melting point.

Explain your answer with reference to bonding and structure.

A student investigates the rate of reaction between sodium thiosulfate and hydrochloric acid, which produces a solid sulfur precipitate.

Na₂S₂O₃  +  2HCl  →  2NaCl  +  S  +  SO₂  +  H₂O

The student places a conical flask over a cross drawn on a piece of paper and measures the time taken for the precipitate to obscure the cross.

In this experiment, the rate of reaction is considered to be 1 / time.

Explain why 1 / time can be used as a measure of the initial rate of reaction.

The student investigates the effect of the concentration of sodium thiosulfate on the rate, keeping all other variables constant. The results are shown below.

State and explain the relationship between the concentration of sodium thiosulfate and the rate of reaction.

Sketch a Maxwell-Boltzmann distribution curve.

On the curve, show and explain why a small increase in temperature has a large effect on the rate of this reaction.

Suggest one reason why measuring the reaction time at a very high temperature (e.g., 80 °C) may be less accurate than measuring it at a lower temperature.

The thiosulfate ion, S₂O₃^2-, contains sulfur in one oxidation state, which is converted into two different oxidation states in the products.

Deduce the oxidation state of sulfur in the thiosulfate ion.

A branched ester is synthesized via the three-step reaction pathway shown below.

Deduce the IUPAC name and draw the displayed structural formula of compounds A and B.

For Step 1 and Step 2, state the class of reaction and a suitable reagent.

Draw the skeletal formula of the final ester product and state its IUPAC name.

The esterification reaction (step 3) is reversible.

State the two reagents and conditions needed to hydrolyse the ester and reform compounds A and B.

This question is about free radical substitution. 

1,2-dibromoethane reacts with bromine in UV light to produce a mixture of further substituted haloalkanes. 

i) Write an equation for the initiation step. 

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ii) Explain why this is an example of homolytic fission. 

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Write two equations showing the propagation of this chain reaction to produce 1,1,2-tribromoethane. 

Traces of 1,2,3,4-tetrabromobutane are found in the reaction mixture. 

i) Write an equation to show how this product is formed. 

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ii) Write a balanced symbol equation to show the overall reaction between 1,1,2-tribromoethane with bromine in UV light to form hexabromoethane. 

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Limonene (C₁₀H₁₆) is a natural cyclic alkene responsible for the characteristic smell of oranges and lemons. It is used in cleaning products, as a fragrance, and as a starting material for chemical synthesis.

i) The structure of limonene contains a chiral centre. Identify the chiral carbon on the structure by marking it with an asterisk (*).

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ii) State the empirical formula of limonene.

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iii) Limonene has several structural isomers that are also cyclic alkenes. Draw the skeletal structure of a structural isomer of limonene that has a five-membered ring.

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The standard enthalpy of combustion (ΔH^θ_c) of liquid limonene is -6110 kJ mol⁻¹.

i) Write a balanced chemical equation for the complete combustion of limonene.

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ii) Calculate the mass of limonene, in grams, that must be burned to release 1000 kJ of heat energy.

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Limonene has two C=C double bonds. When one mole of limonene reacts with exactly one mole of bromine (Br₂) in an inert solvent, the bromine preferentially adds across the double bond that is outside the ring.

i) Draw the skeletal structure of the major organic product of this reaction.

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ii) Explain, in terms of bond stability and steric hindrance, why this double bond is more reactive than the one within the six-membered ring.

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When limonene is treated with excess hydrogen chloride (HCl), addition occurs at both double bonds. According to Markovnikov's rule, a single major final product is formed.

i) Draw the skeletal structure of the final major product.

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ii) The first addition of HCl is faster than the second. Suggest a reason for this difference in reaction rates.

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The complete hydrogenation of one mole of limonene gas consumes two moles of hydrogen gas to form a saturated cyclic alkane called menthane.

C₁₀H₁₆ (g) + 2H₂ (g) → C₁₀H₂₀ (g)

i) Predict the sign of the standard entropy change (ΔS°) for this reaction and justify your answer.

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ii) Given that the reaction is highly exothermic (ΔH^θ is very negative), explain how temperature would affect the spontaneity of this reaction.

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