Quiz 3/30/05 In a group of 2• Active metal oxides react with water to form

hydroxides. ex:

• 1. Na2O + H2O ________ • Halogens react with metals to form salts

• 2. Mg + Cl2 _____• Metals react with oxygen to form oxides

• 3. K + O2 ______• Substances may decompose when exposed to

electricity:

• 4. NaCl ____ + _____• metal carbonates decompose to form metal oxides and carbon

dioxide.

• 5. Al2(CO3)3 ___________+ __________• metal hydroxides decompose to form metal oxides and water.

• 6. Mg(OH)2 _________ + _________

Lab 30 tomorrow! Please do pre-laband summary

Quiz 3/30/05 Answers• Active metal oxides react with water to form

hydroxides. ex:

• 1. Na2O + H2O 2 NaOH_ • Halogens react with metals to form salts

• 2. Mg + Cl2 MgCl2• Metals react with oxygen to form oxides

• 3. 4 K + O2 2 K2O• Substances may decompose when exposed to

electricity:

• 4. 2 NaCl 2 Na + Cl2• metal carbonates decompose to form metal oxides and carbon

dioxide.

• 5. Al2(CO3)3 Al2O3 + 3 CO2• metal hydroxides decompose to form metal oxides and water.

• 6. Mg(OH)2 MgO + H2O

DecompositionAX A + X

• 2MgO 2Mg + O2

OMg

OMg

• CuO

• Fe2O3

• MnO2

• PbO

Cu + O2

Fe + O2

Mn + O2

Pb + O2

422

3

222

Practice decomposing oxides:

Decompositionof metal carbonatesACO3 AO + CO2 (g)• SrCO3 (s) SrO (s) + CO2 (g)

OSr

O

This reactionoccurs when youheat strontium carbonate.

strontium oxide and carbondioxide form.

O

C

• CuCO3

• Na2CO3

• MgCO3

• Ag2CO3

CuO + CO2

Na2O + CO2

MgO + CO2

Ag2O + CO2

Practice decomposing carbonates:

Decompositionof metal hydroxidesAOH AO + H2O (g)• Ca(OH)2 (s) CaO (s) + H2O (g)

H

Ca

O

This reactionoccurs when youheat calcium hydroxide.

calcium oxide and water form.

OH

• NaOH

• Al(OH)3

• Cu(OH)2

• Mg(OH)2

Na2O + H2O

Al2O3 + H2O

CuO + H2O

MgO + H2O

232Practice decomposing hydroxides:

Decomposition of metal chloratesAClO3 ACl + O2 (g)

• 2KClO3 (s) 2KCl (s) + 3O2 (g)

K

O

This reactionoccurs when youheat potassium chlorate.

potassium chloride and oxygen form.

Cl

OK

O

O

ClO

O

• HClO3

• NaClO3

• Cu(ClO3)2

HCl + O2

NaCl + O2

CuCl2 + O2

322

3223

Practice decomposing chlorates:

Decomposition of acidsH2CO3 (aq) H2O (l) + CO2 (g)

Carbonic acid in popdecomposes whenwarmed.

water and carbon dioxide form.

O

OO

C

HH

Combined Practice:• 2 Ag2O

• 2 CuClO3

• Na2CO3

• Ca(OH)2

4 Ag + O2

2 CuCl2 + 3 O2

Na2O + CO2

CaO + H2O