Ozone

Question 1

techniques and procedures for experiments on reaction kinetics –
measuring loss of mass

Answer 1

• Cotton wool allows gas to escape
  but stops acid spraying out (which
  would affect the mass)
• Measure change in mass over time.
• Avoids problem of losing gas at start
  of reaction, but only suitable if
  enough gas will be produced to
  measure a difference in mass
• Units g/s

Question 2

the possible dependence of the
relative reactivities of the haloalkanes
on either bond enthalpy or bond
polarity and how experimental
evidence determines that the
bond enthalpy is more important

Answer 2

Experiment:
* Add 2cm3 ethanol to 2cm3 of 1-chlorobubtane, 1-bromobutane and 1-
iodobutane in separate test tubes
* Warm in water bath
* Add 1cm3 warmed silver nitrate to each tube. The water from this solution acts
as the nucleophile
* Immediately start a timer and record how long it takes for a precipitate to form
in each tube

Question 3

Observations:

Answer 3

• All will form a precipitate. Silver Iodide will form first, followed by silver
  bromide, and silver chloride will take the longest time to form

Question 4

Explanation:

Answer 4

• As the substitution reaction occurs, halide ions are displaced – these form
  precipitates with the silver ions
• 1-iodobutane undergoes hydrolysis first (rate of hydrolysis is fastest).
• Because the C-I bond is weaker that C-Br, which is weaker than C-Cl
• Polarity of these bonds decreases down the group
• The bond enthalpy is the more important factor than polarity in determining
  the rate of this reaction