Redox reactions in Group 7: displacement reactions Flashcards

1
Q

reactions between group 1 or 2 elements with group 7 elements are most vigorous when the reactants are from the ………………of group 1 or 2 and the …………………of group 7 (top or bottom)

A

bottom of group 1 or 2 with top of group 7

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2
Q

when group 1 or 2 elements react with elements in group 7, a ……………is formed which is usually …………………in colour

A

form a white ionic solid salt

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3
Q

reactions between group 1 or 2 metals with a halogen involve an electron transfer to the

A

halogen

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4
Q

when reacting with group 1 or group 2 metals, the halogen’s oxidation number changes from………to………………

A

0 to -1

DECREASES

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5
Q

the equation for the reaction between lithium and chlorine is

A

2Li +Cl2 = 2LiCl

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6
Q

halogens can displace each other if

A

the halogen added to a mixture is more reactive than the halogen in the compound

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7
Q

displacement reactions for halogens occur in (conditions)

A

aqueous solution

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8
Q

halogen / halide displacement reactions involve an observable……….change

A

colour change due to the reaction being carried in aqueous solution

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9
Q

when carrying out halogen / halide displacement reactions, it is good to add …………………at the end to observe the colour change more clearly

A

add an organic solvent such as cyclohexane

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10
Q

why is the colour change for halogen / halide displacement reactions seen more clearly when cyclohexane is added

A

halogens are more soluble in cyclohexane than in water because of the polarity of the H2O molecules. when the halogen is displaced, it then dissolved into the cyclohexane to produce the distincive colour change

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11
Q

the colour change for when iodine is displaced is

A

pale orange/red to purple

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12
Q

the colour change for when bromine is displaced is

A

pale yellow to orange

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13
Q

the colour observed when chlorine dissolves in organic solvent is

A

pale green

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14
Q

chlorine displaces……………….and………………………….
bromine displaces…………………….but not………………
iodine does not displace…………….either………………

A

chlorine displaces bromine and iodine
bromine displaces iodine but not chlorine
iodine does not displace bromine either chlorine

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15
Q

two issues for interpreting colour changes for displacement reactions when water is the solvent are:

A
  • some colours are similar in water (such as iodine and bromine)
  • colours differ with concentration
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16
Q

the equation showing the reaction between chlorine and sodium bromide is:
the ionic equation is:

A

Cl2 + 2NaBr = 2NaCl + Br2

Cl2 + 2Br- = 2Cl- + Br2

17
Q

halogen / halide displacement reactions are

a) redox
b) disproportionation
c) oxidation

reactions?

A

redox as the reacting halogen goes from 0 to -1 and the halide from -1 to 0

18
Q

chlorine is the (second) most reactive halogen because of these two factors:

A
  • it is the smallest atom, so the incoming electron gets closer to and is more attracted by the protons in the nucleus
  • it has the smallest number of complete energy levels of electrons, so the incoming electron experiences the least repulsion