chapter 9 unit 2

Question 1

Na with oxygen

Answer 1

• yellow flame
• white solid mixture of sodium oxide and sodium peroxide
  Formula :
  4Na(s)+O2 –> 2NaO(s)
  2Na(s)+O2 –> Na2O2(s)

Question 2

Magnesium with oxygen

Answer 2

• intense white flame to give magnesium oxide
  Formula :
  2Mg(s) + O2 –> 2MgO(s)

Question 3

Aluminium with oxygen

Answer 3

-protected by tough layers of aluminium oxide
-has to be powered to react
Formula :
4Al(s) + 3O2 –> 2Al2O3

Question 4

Silicon with oxygen

Answer 4

-burn if heated strong enough to form silicon oxide
Formula :
Si(s) + O2 –> SiO2 (s)

Question 5

Phosphorus with oxygen

Answer 5

-white flame produce cloud of white smoke which is phosphorus oxide
Formula :
4P(s) + 5O2 –> P4O10 (s)

Question 6

Sulfur with oxygen

Answer 6

-gentle blue flame which produces colorless sulfur dioxide gas 
Formula : 
S(s) + O2 --> SO2 (g)
Contact process :
2SO2 (g) + O2  2SO3(g) (V2O5)

Question 7

Na with chlorine

Answer 7

-Bright orange flame (heat the metal then put it in jar of chlorine )
- white solid produce
Formula :
2Na(s) + Cl2 –> 2NaCl (s)

Question 8

Magnesium with chlorine

Answer 8

-intense white flame
Formula :
Mg(s) + Cl2 (g) –> MgCl2 (s)

Question 9

Aluminium with chlorine

Answer 9

-pale yellow flame ( burn in stream chlorine )
Formula :
2Al (s) + 3Cl2 –> Al2Cl6

Question 10

Silicon with chlorine

Answer 10

-react slowly
-give silicon tetrahedron
Formula :
Si (s) + 2Cl2 –> SiCl4 (s)

Question 11

Phosphorus with chlorine

Answer 11

2P (s) + 5Cl2 (g) –> 2PCl5 (s)

Question 12

Sodium with water

Answer 12

• Very exothermic reaction cold water
  Formula :
  2Na (s) + 2H2O (l) –> 2NaOh (aq) + H2 (g)

Question 13

Magnesium with water

Answer 13

-slight reaction with cold water
-covered in small bubbles of hydrogen
- Flat surface of Magnesium hydroxide is formed on the top => tends to stop the reaction
Formula :
Mg (s) + 2H2O –> Mg(OH)2 (aq) + H2 (g)
Magnesium burn in steam with white flame
Formula : Mg (s) + H20 –> MgO (s) + H2 (g)

Question 14

Oxidation number of chlorides

Answer 14

• 1 2 3 4 5
• increase in oxidation number
• all oxidation number are positive

Question 15

Oxidation number of oxides

Answer 15

• 1 2 3 4 5 6 4
• Oxygen is always the more electronegative ( - 2 )
• Sulfur ON are 4 because only 4 of it’s electron are involved in bonding