WATP (2018) Flashcards
1
Q
pH scale is a measure of the concentration of hydrogen ions in a solution. According to Arrhenius theory, if bases are substances that produce hydroxide ions in solution, how can their pH be measured? (3)
A
- All aqueous solutions have some hydrogen ions present.
- Bases contain a very low concentration of hydrogen ions.
- A low concentration of hydrogen ions corresponds to a high pH.
2
Q
Define an enzyme and explain in terms of the collision theory how it increases the rate of reaction. (3)
A
- An enzyme is a protein known as a biological catalyst.
- provides an alternative reaction pathway with a lower activation energy.
- allows a greater proportion of particles to overcome the activation energy resulting in greater number of particles having collision energy greater than activation energy.
3
Q
A substance is conductive (s&l) and insoluble in water. Why is it likely to be malleable? (3)
A
- Conductive when solid and liquid => metal.
- Metals have delocalised sea of elections.
- When a force is applied they can distort without disrupting bonding.
4
Q
Why does NaOH(aq) have higher pH than NH3(aq). (4)
A
- NaOH is a strong base whereas NH3 is weak.
- NaOH completely dissociates in solution producing OH- ions.
- NH3 only partially ionises in solutions to produce a small amount of OH- ions.
- Higher concentration of OH- ions corresponds to higher pH.
5
Q
What is the function of a catalytic converter? (1)
A
- Reduce pollutant like unburnt petrol, CO, and nitrous oxides by converting them to harmless substances like carbon dioxide and nitrogen.
6
Q
Predict whether propane or propene would have a higher boiling point. Justify using relevant chemical understanding. (4)
A
- Both substances are non-polar.
- => both substances only have dispersion forces.
- since propane has the higher molar mass it would have stronger dispersion forces.
- Stronger dispersion forces means propane would have a higher boiling point.
