Chapter 8 Reactivity Trends Flashcards

1
Q

what is a reducing agent?

A

an element that reduces another species

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2
Q

what type of reaction is common for group 2 metals?

A

redox ( oxidisation)

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3
Q

what is the general formula for a reaction between group 2 metal and oxygen?

A

MO

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4
Q

what are the products of a group 2 metal reacting with water?

A

An alkaline hydroxide = M(OH)2 + h2

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5
Q

what is the equation for a redox reaction between a metal and a acid

A

metal + acid —- salt + hydrogen

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6
Q

does reactivity increase or decrease down group 2 elements?

A

reactivity increases

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7
Q

why does reactivity increase down group 2?

A

more shells so larger atomic radius and increased shielding affect reducing nuclear attraction to outermost electron therefore reducing ionisation energy

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8
Q

what is the equation for group 2 oxides reacting with water?

A

CaO + H2O —— Ca^+2 + 2OH-

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9
Q

how are group 2 hydroxides formed?

A

Ca+2 + 2OH- ——– Ca(OH)2

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10
Q

are group 2 hydroxides soluble?

A

they are slightly soluble and increase solubility down the group with a solution containing more OH so is more alkaline

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11
Q

what are the uses of group 2 compounds?

A

Calcium Hydroxide is added to fields as lime to increase pH of acidic soils by neutralising acid and forming water
Ca(OH)2 + 2H2 —— Ca+2 + H20

Group 2 bases are used as antacids for treating acid indigestion using mangenium and calcium carbonates with suspension of magnesium hydroxide
Mg(OH)2 + 2HCl ——– MgCl2 + H20
CaCO3 + 2HCL ——– CaCl2 + H20 + CO2

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12
Q

which halogens are gas, liquid or solid?

A

Fluorine - pale yellow gas
chlorine - plae green gas
bromine - red-brown liquid
iodine - shiny grey black solid
At - never seen

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13
Q

why does halogens boiling point increase down the group?

A

more electrons so stronger london forces therefore more energy needed to break intermolecular forces as a result boiling point increases

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14
Q

what is the redox reaction for halogen?

A

Cl2 + 2e —— 2Cl-
each halogen atom gains an electron to become reduced forming halide ion. Halogen is an oxidising agent as it has oxidised another species

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15
Q

what is a halogen-halide displacement reaction?

A

halogen displaces halide from solution causing solution to change colour

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16
Q

what does a halogen-halide displacement reaction show?

A

shows that reactivity of halogens decrease down the group

17
Q

what colour is formed from bromine formation?

18
Q

what colour is formed from iodine formation?

19
Q

can a chloride react with Bromine?

20
Q

can a bromide react with chlorine?

21
Q

can an iodide react with both chlorine and bromine?

22
Q

why does reactivity and tendency to gain electron decrease down the halogen group?

A

atomic radius increases and more inner shells so shielding increases which reduces nuclear attraction to gain electron from other species therefore reactivity decreases

23
Q

what is disproportionation?

A

a redox reaction where the same element becomes both oxidised and reduced

24
Q

what is the equation for chlorine with water?

A

Cl2 + h20 —— HClO + HCL
disproportionation takes place

25
what is the equation for chlorine with cold dilute sodium hydroxide?
Cl2 + 2NaOH ------ NaClO + NaCl + h2O
26
what are the benefits and risks for chlorine use?
Benefits: -kills bacteria in water -reduces diseases like Typhoid and Cholera in water Risks: -it is a respiratory irritant -toxic gas - chlorine in water can react with hydrocarbons to form chlorinated hydrocarbons which may cause cancer
27
what is the test for halide ions?
halide ions react with silver ions to form precipitates of silver halides Ag+ + X- ------ AgX
28
how are reducing ability of halide ions shown?
shown by reacting halides with sulfuric acid Chlorine ions cannot reduce H2SO4 bromines ions can reduce h2so4 to so2 2h+ + h2so4 + 2br- ----------- so2 + br2 + 2h2o iodine reduces so2 to s and further reduces to hydrogen sulfide h2s
29
What observation is shown if a solution containing iodide ions is added to silver nitrate
Cream precipitate
30
What is the order of reactivity of halogens
cl>I>br
31
When bromine is displaced it forms brown colour. When iodine is displaced it forms brown colour. How are these differentiated
Add organic solvent such as solvent which makes iodine from orange to violet . Chlorine remains green and bromine remains brown