CHURCHLANDS 2022 CHEM SEM 2

(a) Hydrochloric acid is a strong acid.

(b) Ethanoic acid is a weak acid.

(c) Sodium hydroxide is a strong base.

(d) Calcium carbonate is a weak base. (correct)

To (catalyse reactions which) reduce the amount of harmful gases (e.g. carbon monoxide, unburnt petrol and nitrogen oxides) emitted by a vehicle.

Nanoparticles have a very large surface area (to mass ratio).

This increases the frequency of collisions between the catalyst and the gases.

Therefore less material is required (compared to the bulk) to provide an equivalent surface area / to function effectively.

<p>Hexane is non-polar and exhibits only dispersion forces.</p> <p>Water and ethanol exhibit strong hydrogen bonds (in addition to dipole- dipole and dispersion forces).</p> <p>Thus the sum of intermolecular forces is lower in hexane, allowing vapour to form/evaporation to occur/molecules to escape the liquid more easily.</p> <p>hence the vapour pressure of hexane is much higher than the other two liquids</p> Signup and view all the answers

<p>Boiling occurs when the vapour pressure equals the atmospheric pressure</p> <p>thus a lower vapour pressure indicates a larger amount is required before boiling will occur</p> Signup and view all the answers

<p>An increase in temperature increases the average kinetic energy of the particles.</p> <p>This would allow a higher proportion of molecules to evaporate/increase rate of evaporation</p> <p>Resulting in increased collisions between the vapour and the container.</p> Signup and view all the answers

<p>Oxalic acid</p> <p>the mobile phase is power</p> <p>therefore components with highest polarity will dissolve more readily in the mobile phase</p> <p>thus (they will move more quickly through the column), resulting in a lower retention time</p> Signup and view all the answers