Elements of life 7

Question 1

What is ionic bonding ?

Answer 1

1. When metals react with non-metal in a chemical reaction, ions are only formed if the overall energy change for the reaction is favourable.
2. The oppositley charged ions attract each other strongly in an ionic bond

Question 2

What is electrostatic bond ?

Answer 2

1. The cations and anions formed are held together by their opposite charges .

Question 3

write the formula of chromium (iii) hydroxide

Answer 3

1. identify the atoms and charges a compound is made of - chromium (iii) hydroxide is made up of chromium(iii) ions (Cr3+) and hydroxide ions (OH-)
2. to balance +3 charge u need three -1 charges = formula Cr(OH)3

Question 4

1. Acid + alkali
2. Acid + base
3. Acid + carbonate
4. Acid + metal

Answer 4

1. salt + water
2. salt + water
3. salt + water + carbon dioxide
4. Salt + hydrogen

Question 5

Many ionic substances dissolve readily in water but some ionic compounds that are not soluble are :

Answer 5

1. barium , calcium, lead and silver sulfates
2. silver and lead halides (chlorides, bromides and iodides)
3. all metals carbonate
4. metal hydroxides ( except group 1 hydroxides and ammonium hydroxide )

Question 6

what happenes if you add solution of sodium chloride to silver nitrate solution ?

- with equation

Answer 6

• you get a white precipitate of silver chloride
• the silver ions ( Ag+) and chloride ions (Cl - ) have come together to form insoluble silver chloride which precipitates out
• Ag+ (aq) + Cl- (aq) = AgCl (s)

Question 7

What are the spectator ions in the reaction between sodium chloride and silver nitrate?

Answer 7

The Na+(aq) and NO3- (aq) ions are not involved in the reaction so can be left out of the equation
= spectator ions

Question 8

What is the bonding, structure of an ionic bonding( giant ionic lattices) ?

Answer 8

• Ionic compound are typically solids at room temp and pressure
• it has a lattic structures consiting of repeating positive (+ = smaller ) and negative (- bigger) ions in all three dimensions

Question 9

Does ionic bond have high or low meltjing point and why ?

Answer 9

The electrostatic force attarction are strong this means a large amount of energy is needed to pull the ions apart so they have a high melting point

Question 10

Can ionic bond conduct electricity ?

Answer 10

• once melted the ions are free to move and this is why the molten ionic compounds can conduct electricty

Question 11

Describe the structure/ bondong in a giant mettalic lattice

Answer 11

1. All metals/metallic bonds have giant metallic lattice structure
2. has a strong electrosatic attraction between the positive metal ions and the delocalised electrons between the ions

Question 12

Name 3 types of ionic substance which are always soluble in water

Answer 12

• group 1 compounds
• ammonium compounds
• Nitrates

Question 13

How would you test for Cu2+ ions? Name the change observed and the product responsible.

Answer 13

Precipitation reaction

• Add NaOH solution to Cu2+ solution
• Blue copper(II) hydroxide, Cu(OH)2, precipitate forms

blue- green flame test

Question 14

How would you test for Fe2+ ions? Name the change observed and the product responsible.

Answer 14

Precipitation reaction

• Add NaOH solution to Fe2+ solution
• Dirty green iron(II) hydroxide, Fe(OH)2, precipitate forms

no flame test

Question 15

How would you test for Fe3+ ions? Name the change observed and the product responsible.

Answer 15

Precipitation reaction

• Add NaOH solution to Fe3+ solution
• Orange-brown iron(III) hydroxide, Fe(OH)3, precipitate formed

Question 16

How would you test for Pb2+ ions? Name the change observed and the product responsible.

Answer 16

Precipitation reaction

Add KI solution to Pb2+ solution
Yellow lead iodide, PbI2, precipitate forms
(No flame test)

Question 17

How would you test for Cl- ions? Name the change observed and the product responsible.

Answer 17

Precipitation reaction

Add AgNO3 solution to Cl- solution
White silver chloride, AgCl, precipitate formed

Question 18

How would you test for Br- ions? Name the change observed and the product responsible.

Answer 18

Precipitation reaction

Add AgNO3 solution to Br- solution
Cream silver bromide, AgBr, precipitate forms

Question 19

How would you test for I- ions? Name the change observed and the product responsible.

Answer 19

Precipitation reaction

Add AgNO3 solution to I- solution
Yellow silver iodide, AgI, precipitate forms

Question 20

What are the colours of the respective precipitates formed when solutions of chloride, bromide and iodide are reacted with silver nitrate solution?

Answer 20

Chloride = white
Bromide = cream
Iodide = yellow
More saturated colour down group

Question 21

How would you test for SO42- ions? Name the change observed and the product responsible.

Answer 21

Precipitation reaction

Add BaCl2 solution to SO42- solution
White barium sulfate, BaSO4, precipitate forms

Question 22

what are the characteristic properties of giant metallic lattices?

Answer 22

• high melting point because there is strong electrosatic attraction between ions + electrons
• insoluble in water
• conduct electricity when solid/ molten because delocalised electrons are free to move in response to voltage

Question 23

what are the characteristic properties of giant covalent networks?

Answer 23

• High melting point because all bonds in structure are strong covalent bonds
• insoluble in water
• do not conduct electricity (apart from graphite)

Question 24

what are the types of covalent networks?

Answer 24

• carbons in form of diamond
• silicon dioxide (SiO2)
• graphite

Question 25

what are the tyoes of covalent molecular?

Answer 25

• simple molecular
• Macromolecular

Question 26

describe the properties of simple molecular:

Answer 26

• non metal with non metal eg CO2, Cl2,H2O
• it contains small molecules
• they have weak intermolecular bonds between molecules so they have low melting point- strong covalent bonds between the atom within molecules
• do not conduct electrcity
• usually insoluble in water unless molecules contain groups which can hydrogen bond with water
• usually soluble in non polar solvents