AQA A LEVEL CHEMISTRY ORGANIC AND PHYSICAL CHEMISTRY PAPER 2 QP 2020

AQA A LEVEL CHEMISTRY ORGANIC AND
PHYSICAL CHEMISTRY PAPER 2 QP 2020
1. Define the term standard enthalpy of formation
- ANSWER: The enthalpy change when 1 mol of a substance is former from its
element with all reactants and products in their standard states

2. The equation for a reaction used to manufacture 1-chloropropane is:

3CH3CH2CH2OH(I) + PCl3(I) --> 3CH3CH2CH2Cl(I) + H3PO3(s)

The enthalpy change for this reaction, Enthalpy change = -114kJ mol-1

Substance : Enthalpy of formation
PCl3(I) : -339
CH3CH2CH2Cl(I) : -130
H3PO3(s) : -972

Calculate the value for the standard enthalpy of formation of propane-1-ol using
the enthalpy change for the reaction and data from Table 1.
- ANSWER: Enthalpy change = [sum (enthalpy of formation) products] - [sum
(enthalpy of formation) reactants]
3x = 3(-130) - 972 +339 = 114
x = -303 kJ mol-1

3. Why is ultra violet light needed in free radical substitution? - ANSWER:
Ultraviolet provides energy to break the single covalent bond between Cl-Cl

4. Define the term electronegativity - ANSWER: The ability of an atom to attract
the pair of electrons in a covalent bond

5. Suggest, by considering the product of Sulphur in this reaction, why small
amounts of reactants are used in this experiment - ANSWER: SO forms a toxic #$%^&*&^
gas %$#$%^&*
*&^%$#$%
6. Suggest why the student chose not to carry out experiments at temperatures in ^&*()(*&^
the range 1-10 degrees Celsius - ANSWER: Reaction would take too long
%$#%^&*(
7. A student investigates two experimental methods of making methylpropanal. *&^%$%^&
In each method the student uses 1.00g organic starting material. *()*&^%$%
^&*()*&^%
The yield of methylpropanal obtained using each method and other data are $%^&*()(*
included in Table 3.
Method 1 Method 2 &^%$%^&*
Yield of methylpropanal 552mg 778mg ()(*&^%$%
^&*(*&^%
%^&*()(*&
^%$%^&*(
(*&^%$%^
&*()(*&^%