# 22/23: Main Group Elements


These are homework exercises to accompany the Textmap created for "General Chemistry: Principles and Modern Applications " by Petrucci et al. Complementary General Chemistry question banks can be found for other Textmaps and can be accessed here. In addition to these publicly available questions, access to private problems bank for use in exams and homework is available to faculty only on an individual basis; please contact Delmar Larsen for an account with access permission.

## Q1A

Write chemical equations for the reactions you would expect to occur:

1. the reaction of fluorine gas with potassium metal
2. lithium fluoride and water are formed when hydrofluoric acid is added to lithium oxide
3. cesium burns in air to form cesium superoxide.

### S1A

1. 2 K(s) + F2(g) → 2 KF2(s)
2. Li2O(s) + 2HF (l) → 2 LiF(s) + H2O(l)
3. Cs(s) + O2(g) → CsO2(s)

## Q1B

Which of the following ions would most likely react with the krypton: C, N3, F2, Li+

### S1B

F2 is the most likely to react with the noble gas Kr. Only highly electronegative elements can cause a reaction with noble gases, and F2 is the most electronegative of the group. This reaction will cause the formation of KrF2.

## Q1C

Construct the chemical equations for:

1. The reaction of potassium metal with chlorine gas
2. The formation of barium peroxide
3. The thermal decomposition of calcium carbonate

### S1C

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements

1. $$K_{(s)} + Cl_{2 (g)} \rightarrow 2 KCl_{(s)}$$
2. $$Ba_{(s)} + O_{2 (g)} \rightarrow BaO_{2 (s)}$$
3. $$CaCO_{3 (s)} \rightarrow CaO_{(s)} + CO_{2 (g)}$$

## Q1D

Predict the chemical equation for:

1. potassium metal with liquid bromine
2. production of lithium oxide
3. decomposition of sodium carbonate

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements

### S1D

1. $$2K_{(s)} + Br_{2(l)} → 2KBr_{(s)}$$
2. $$4Li_{(s)} + O_{2(g)} → 2Li_2O_{(s)}$$
3. $$Na_2CO_{3(s)} → Na_2O_{(s)} + CO_{2(g)}$$

## Q1E

Use information from the chapter to write balanced chemical reactions:

1. Reaction of potassium with chlorine gas
2. The formation of NaCl and H2O from the addition of HCl to the reactant
3. Combustion of littium in oxygen. What is the product called?

### S1E

1. $$2 K_{(s)} + Cl_{2(g)} → 2 KCl_{(s)}$$
2. $$Na_2O_{(s)} + 2 HCl_{(l)} → 2 NaCl_{(s)} + H_2O_{(l)}$$
3. $$4 Li_{(s)} + O_{2(g)} → 2 Li_2O_{(s)}$$

## Q3

Which of the following would be the worst oxidizing agent of the group: F2, Br2, Cl2, At2, I2?

### S3

Oxidizing agents are elements that are themselves reduced. Therefore, we are measuring the element that has the lowest ability to become reduced or gain electrons. Since all of the elements are in group 17 and electronegativity decreases down a group, this means that At2 is the least likely to gain an electron. Therefore, At2 is the worst oxidizing agent of the group.

What chemical reaction would cause a metal sulfide, FeS(s), reacting with hydrochloric acid?

Write the double replacement reaction between FeS(s) and HCl(aq):

$FeS_{(s)} + 2HCl_{(aq)} \rightarrow FeCl_{2(aq)} + H_2S_{(g)}$

## Q17A

Write chemical equations for the reactions you would expect to occur:

1. magnesium reduces calcium chloride into calcium metal.
2. Reaction of beryllium metal with fluorine gas
3. Sulfuric acid reacts with an amount of calcium oxide

### S17A

1. (s)MgCl2 → Ca(s) + (s) + Mg(s)CaCl2A)
2. (s)BeF2B) Be(s) + F2(g) →
3. H2SO4(aq) + CaO(s) → CaSO4(s) + H2O(l)

## Q17B

Predict the chemical equation for:

1. breakdown of $$MgCl_2$$ in the presence of $$Ca$$, a reducing agent
2. reaction of chlorine gas with solid calcium
3. decomposition of slacked lime

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements

### S17B

1. $$MgCl_{2(s)} + Ca_{(s)} → CaCl_{2(s)} + Mg_{(s)}$$
2. $$Ca_{(s)} + Cl_{2(g)} → CaCl_{2(s)}$$
3. $$Ca(OH)_{2(s)} → CaO_{(s)} + H_2O_{(l)}$$

## Q17C

Write chemical equations for the reactions you would expect to occur:

1. The reduction of CaF2 to Ca metal with Ba as the reducing agent.
2. Reaction of strontium metal with Cl2(l)
3. Complete neutralization of hydroflouric acid with quicklime

### S17C

1. $$CaF_{2(s)} + Ba_{(s)} → Ca_{(s)} + BaF_{2(s)}$$
2. $$Sr_{(s)} + Cl_{2(l)} → SrCl_{2(s)}$$
3. $$2HF_{(aq)} + CaO_{(s)} → CaF_{2(s)} + H_2O_{(l)}$$

## Q17D

Write a chemical equation for:

1. The reduction of MgCl2(s) to magnesium metal with calcium as a reducing agent
2. The reaction of beryllium metal with Cl2(g) at high temperatures
3. The neutralization reaction of sulfuric acid and ammonium hydroxide

### S17D

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements

1. $$MgCl_{2(s)} + Ca_{(s)} → Mg_{(s)} + CaCl_{2(s)}$$
2. $$Be_{(s)} + Cl_{2(g)} → BeCl_{2(s)}$$
3. $$H_2SO_{4 (aq)} + 2NH_4OH_{(aq)} \rightarrow (NH_4)_2SO_{4 (s)} + 2H_2O_{(l)}$$

## Q39A

What are diamonds made of? What forces hold them together and although it may not seem like it, how are graphite and diamonds related?

### S39A

Diamonds/graphite are both composed entirely of carbons. While graphite is very soft, the carbon atoms of diamonds form one of the hardest known substances. In diamonds, each carbon atom is the same distance from each other. This forms a rigid network and this doesn't allow the atoms to move. Graphite, on the other hand, has strong covalent bonds between carbon atoms but has weak forces between the different carbon layers. Diamonds are covalent network solids.

## Q39B

What properties contribute to the high melting points found in diamonds?

### S39B

Connected via covalent bonds, carbon atoms act as the building blocks of diamond and possess the unique ability to join together to form highly stable cubic structures. The extreme stability of these carbon bonds is very difficult to overcome and contributes to the observably high melting points of diamond structures. http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements

## Q39C

Name 3 difference between diamond and graphite.

### S39C

Diamonds are bad conductors, very hard, transparent, and crystallize in an isometric system
Graphite are good conductors, very brittle, opaque, and crystallize in a hexagonal system

## Q41A

Write a chemical equation to represent:

1. The reduction of Lead(II)Oxide by aluminum
2. Thallium carbonate is created with thallium(I) hydroxide with carbon dioxide

### S41A

1. (s)3Sn(s) + Al2O3(s) → 2Al(s) + 3SnOA)
2. C) TiOH(aq) + CO2(g) → TiCO3(s) + H+(aq)

## Q41B

Write a chemical equation for:

1. The reduction of Lead (ii) Oxide to elemental lead by heating with carbon
2. The reaction of Na2Si with water to produce sodium silicate

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements

### S41B

1. $$PbO_{(s)} + C_{(s)} → Pb_{(l)} + CO_{(g)}$$
2. $$Na_2Si_{(s)} + 3H_2O_{(l)} → Na_2SiO_{3(aq)} + 3H_{2(g)}$$

## Q41C

Write a chemical equation to represent:

1. The reduction of Tin(II)Oxide by aluminum
2. The reaction of CO2(g) with water

### S41C

1. $$3SnO_{(s)} + 2Al_{(s)} → Al_2O_{3(s)} + 3Sn_{(s)}$$
2. $$H_2O_{(l)} + CO_{2(g)} → \underset{\text{Carbonic Acid}}{H_2CO_{3(aq)}}$$

## Q41D

Predict the chemical equation for:

1. the formation of methane from the reaction of Ga4C3 and water
2. the breakdown of germanium dioxide in the presence of boron

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements

### S41D

1. Ga4C3(s) + 12H2O(l) → 3CH4(g) + 4Ga(OH)3(s)
2. 3GeO2(s) + 4B(s) →2B2O3(s) + 3Ge(s)

## Q49

Write plausible chemical equations for the:

1. Preparation of sodium metasilate by high temp fusion of (silica) and (sodium carbonate)
2. Creation of Tin(l) and carbon monoxide gas. (Hint: reduction of carbon)
3. Dissolving Tin(II) oxide in nitric acid
4. Reduction of Au3+(aq) to Au1+(aq). How many electrons are transferred?
5. Heating of PbCO3(s)

### S49

1. 3 NaO2(s) + SiO2(s) → CO2(g) + Na2SiO3(s)
2. SnO(s) + C(s) → Sn(l) + CO(g)
3. SnO(s) + HNO3(aq) → Sn(NO3)2(s) + H2O(l)
4. Au3+(aq) + 3e- → Au1+ 3 electrons transferred in this reaction
5. PbCO3(s) → PbO(s) + CO2(g)

## Q49

Predict the chemical equation for:

1. lead(II) oxide in hydrochloric acid
2. thermal decomposition of SiCO3(s)
3. reaction of tin(II)oxide and carbon, a reducing agent

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements

### S49

1. PbO(s) + 2HCl(aq) → PbCl2(s) + H2O(l)
2. SiCO3(s) → SiO(s) + CO2(s)
3. SnO(s) + C(s) →Sn(s) + CO(g)

## Q49

Write chemical equations for:

1. Dissolving calcium carbonate in sulfuric acid
2. The production of stannic oxide (through heating process)
3. The heating of copper chloride
4. The reduction of Sn(IV) to Sn(I) using magnesium as a reducing agent (Hint: Start with SnCl4)
5. The combustion of disilane

### S49

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Main_Group_Elements

1. CaCO3(s) + H2SO4(aq) → CaSO4(aq) + CO2(g) + H2O(l)
2. Sn(s) + O2(g) → SnO2(s)
3. 2CuCl2 (aq) → 2 CuCl (aq) + Cl2(g)
4. 2Mg(s) + SnCl4(aq) → 2 MgCl2(aq) + Sn(s)
5. 2Si2H6(s) + 7 O2(g) → 4 SiO2(g)+ 6 H2O(l)

## Q73

What is the chemical equation for the formation of an ionic hydride from the element Na?

### S73

$2Na_{(s)} + H_{2(g)} \rightarrow 2NaH_{(s)}$