Comparing the Rates of Hydrolysis Reactions Flashcards Preview

Chemistry 6 - Organic Chemistry > Comparing the Rates of Hydrolysis Reactions > Flashcards

Flashcards in Comparing the Rates of Hydrolysis Reactions Deck (11)
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1
Q

why can silver nitrate solution be used in a test for halide ions

A
  • because the silver ions in silver nitrate react with the halide ions formed in the hydrolysis (with water in the solution)
  • to give a precipitate
2
Q

what is the general formula for this occurring

A

Ag+ + X- = AgX

3
Q

how could we use this to determine how quickly the hydrolysis reaction occurs

A

be observing how quickly the precipitate of AgX forms

4
Q

why couldnt you tell the rate of the reactions without the percipitate

A

because both reagents and the products are colourless

5
Q

what are the three things the comparison of the rates of reaction involves

A
  • using ethanol as the solvent for the mixture
  • controlling variables like temperature and the concentration and quantity of the halogenoalkanes
  • timing the appearance of the precipitate
6
Q

why does ethanol need to be used as a solvent for the mixture

A
  • because halogenoalkanes and aqueous silver nitrate dont mix
  • but from separate layers
  • ethanol is needed to prevent this
7
Q

why is difficult to time the appearance of the precipitate

A

because a precipitate may appear faint but become thicker over time

8
Q

what is the general trend you should observe about how much precipitate is formed as you go down group 7

A
  • more and thicker precipitates are formed as you go down the group
  • due to the halogenoalkanes being less reactive as you go down group 7
9
Q

why would you expect the halogens at the top of the group to form the precipitates the quickest regarding their bonds

A
  • the electronegativity of the elements in group 7 increase as you go up the group
  • meaning the o+ charge on the carbon atom would also increase
  • so the attacking nucleophile should be attracted more strongly
10
Q

despite that prediction, why do the elements down the group experience the fastest results when reacted with silver nitrate in the same conditions

A
  • the bond energies between the carbon atom and the halogen decrease as you do down the group
  • weaker bonds break more easily than stronger bonds, so the bonds between the carbon atom the halogen as you go down the group require less energy to break
  • this means that for the same conditions, the C-X bond breaks most easily as you go down the group, so the precipitate forms more quickly
11
Q

what is the trend in how quickly precipitates are formed regarding what the classification of halogenoalkane is

A
  • tertiary halogenoalkanes react the quickest with the silver nitrate to form the precipitate the quickest
  • primary halogenoalkanes are the slowest
  • with secondary ones being in between