(a) A hydrocarbon having the formula C\(_{10}\)H\(_{22}\) was cracked to produce C\(_6\)H\(_{14}\) and another hydrocarbon P.
(i) Give the molecular formula of P.
(ii) Draw the structures of two isomers of P.
(ii) Give a reason why P could be polymerized.
(b) State the guiding principles which are used to explain the way electrons of the atoms of the elements are arranged in atomic orbitals.
(c)Consider each of the following substances: NaH, H\(_2\), H\(_2\)S, NH\(_4\)Cl.
(i) Describe the nature of the intermolecular forces holding the units or molecules together in the condensed (liquid or solid) state.
(ii) Explain briefly what happens when a sample of each of the substances is added to water.
(iii) Write the chemical equations of any reactions occurring or of any equilibria established.
(d) Element J has the following electron configuration: Is\(^2\)2s\(^2\)2p\(^6\)3s\(^2\).
(i) How many unpaired electrons can be found in J?
(ii) State whether J would be a good oxidizing or reducing agent.
(iii) Give a reason for the answer in (d)(ii).
(a)
(i) The molecular formula of hydrocarbon P can be determined by balancing the carbon and hydrogen atoms in the reactant and products of the cracking reaction. The balanced equation is:
C10H22 → C6H14 + C4H8
Therefore, the molecular formula of hydrocarbon P is C4H8.
(ii) Two isomers of hydrocarbon P are:
1. But-1-ene:
H H
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H-C=C-C-C-H
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H H
2. But-2-ene:
H H
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H-C-C=C-C-H
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H H
(iii) Hydrocarbon P could be polymerized because it contains a carbon-carbon double bond, which can undergo addition polymerization to form a long chain polymer.
(b)
The guiding principles used to explain the way electrons of the atoms of the elements are arranged in atomic orbitals are the Aufbau principle, the Pauli exclusion principle, and Hund's rule.
The Aufbau principle states that electrons fill atomic orbitals in order of increasing energy level, starting with the lowest energy level.
The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers.
Hund's rule states that for a set of orbitals of equal energy (degenerate), the lowest energy is attained when the number of electrons with the same spin is maximized.
(c)
(i) NaH has ionic bonds holding the units together, while H2, H2S, and NH4Cl have covalent bonds holding the molecules together.
(ii) When NaH is added to water, it reacts to form hydrogen gas and sodium hydroxide:
NaH + H2O → NaOH + H2
When H2 is added to water, it dissolves and forms a homogeneous mixture.
When H2S is added to water, it reacts to form hydrosulfuric acid:
H2S + H2O ⇌ H3O+ + HS-
When NH4Cl is added to water, it dissolves and dissociates into ammonium cations and chloride anions:
NH4Cl → NH4+ + Cl-
(iii) The chemical equations for the reactions are:
NaH + H2O → NaOH + H2
H2S +
(a)
(i) The molecular formula of hydrocarbon P can be determined by balancing the carbon and hydrogen atoms in the reactant and products of the cracking reaction. The balanced equation is:
C10H22 → C6H14 + C4H8
Therefore, the molecular formula of hydrocarbon P is C4H8.
(ii) Two isomers of hydrocarbon P are:
1. But-1-ene:
H H
| |
H-C=C-C-C-H
| |
H H
2. But-2-ene:
H H
| |
H-C-C=C-C-H
| |
H H
(iii) Hydrocarbon P could be polymerized because it contains a carbon-carbon double bond, which can undergo addition polymerization to form a long chain polymer.
(b)
The guiding principles used to explain the way electrons of the atoms of the elements are arranged in atomic orbitals are the Aufbau principle, the Pauli exclusion principle, and Hund's rule.
The Aufbau principle states that electrons fill atomic orbitals in order of increasing energy level, starting with the lowest energy level.
The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers.
Hund's rule states that for a set of orbitals of equal energy (degenerate), the lowest energy is attained when the number of electrons with the same spin is maximized.
(c)
(i) NaH has ionic bonds holding the units together, while H2, H2S, and NH4Cl have covalent bonds holding the molecules together.
(ii) When NaH is added to water, it reacts to form hydrogen gas and sodium hydroxide:
NaH + H2O → NaOH + H2
When H2 is added to water, it dissolves and forms a homogeneous mixture.
When H2S is added to water, it reacts to form hydrosulfuric acid:
H2S + H2O ⇌ H3O+ + HS-
When NH4Cl is added to water, it dissolves and dissociates into ammonium cations and chloride anions:
NH4Cl → NH4+ + Cl-
(iii) The chemical equations for the reactions are:
NaH + H2O → NaOH + H2
H2S +