Past paper questions Flashcards
(12 cards)
Suggest why chloroethanoic acid is a stronger acid than ethanoic acid
Cl is an electron withdrawing group so weakens the OH bond
Define the term enthalpy of lattice formation.
enthalpy change when 1 mol of solid ionic compound is formed from its gaseous ions
A calculation of the enthalpy of lattice formation of silver iodide based on a
perfect ionic model gives a smaller numerical value than the value calculated in Question 1.2
Explain this difference.
AgI contains some covalent character so forces are stronger
Predict whether the pH of the magnesium hydroxide solution formed at 10 °C is larger than, smaller than or the same as the pH of the calcium hydroxide solution at 10 °C
Explain your answer.
lower pH as magnesium hydroxide is less soluble because solubility of hydroxides in group 2 increases down the group
Describe how a student could distinguish between aqueous solutions of magnesium chloride, MgCl2, and aluminium chloride, AlCl3, using one simple test-tube reaction.
NaOH
MgCl2 - white precipitate
AlCl3 - white precipitate which dissolves in excess
Explain why sodium oxide can be identified as a basic oxide when dissolved in water.
contains O2- ions which accept protons to form OH-
State the colour of the flame produced when sulfur is burned in oxygen
blue
Suggest an advantage and disadvantage of using ethanoic anhydride instead of ethanoyl chloride
doesn’t produce hydrogen chloride which is toxic
slower rate of reaction
Explain how sulfuric acid behaves as a catalyst in the nitration of benzene
present at the start of the reaction and forms an intermediate
sulfuric acid is regenerated
Why is a vacuum used to collect the distillate?
less energy to heat mixture
Outline the method for recrystallisation
dissolve in minimum volume of hot solvent
filter and allow to cool
filter under reduced pressure
wash with cold solvent
dry
The larger the relative intensity in mass spec….
the more stable the ion
