Hkcee Chemistry 2007 Paper 1
HKCEE Chemistry 2007 Paper 1
Section A 1. A is a compound formed from oxygen and magnesium, while B is a compound formed from oxygen and fluorine. a) Draw the electronic diagram of A, showing electrons in he outermost shells only.
(1)
b) Draw the electronic diagram of B, showing electrons in the outermost shells only.
(1)
c) Compare the melting points of A and B. Explains your answer.
Melting point of A is higher than that of B.
Ions of A are linked by strong ionic bonds / electrostatic force forming giant crystal lattice. (1)
Molecules of B are attracted by weak van der Waals’ forces / intermolecular forces. (1)
2. A student performed an experiment to crack paraffin oil and collect the gaseous products by using a boiling tube. a) Draw a labeled diagram to show how this experiment can be performed in the laboratory.
b) (i) The student added a few drops of bromine water into the boiling tube containing the gascous products. The brown colour of bromine water disappeared immediately. Why?
The products of cracking contained unsaturated (hydrocarbons) / alkenes / C=C / ethane / reasonable name of alkene, which decolourised the bromine water immediately by addition reaction (2)
(II) The student then dropped more bromine water into the boiling tube until the brown colour of the bromine water persisted. After about 10 minutes, the brown colour disappeared. Why?
The products of cracking also contained saturated (hydrocarbons) / alkanes / methane/reasonable name or molecular formula of alkane, which decolourised the bromine water slowly by substitution reaction. (2)
3. The diagram below shows the set-up used in performing a microscale experiment. A drop of hydrochloric acid was added to the drop of chlorine bleach in a petri dish was immediately covered with is lid. Chlorine gas formed by the reaction between chlorine bleach and hydrochloric acid eventually filled up the whole set-up.
Section A 1. A is a compound formed from oxygen and magnesium, while B is a compound formed from oxygen and fluorine. a) Draw the electronic diagram of A, showing electrons in he outermost shells only.
(1)
b) Draw the electronic diagram of B, showing electrons in the outermost shells only.
(1)
c) Compare the melting points of A and B. Explains your answer.
Melting point of A is higher than that of B.
Ions of A are linked by strong ionic bonds / electrostatic force forming giant crystal lattice. (1)
Molecules of B are attracted by weak van der Waals’ forces / intermolecular forces. (1)
2. A student performed an experiment to crack paraffin oil and collect the gaseous products by using a boiling tube. a) Draw a labeled diagram to show how this experiment can be performed in the laboratory.
b) (i) The student added a few drops of bromine water into the boiling tube containing the gascous products. The brown colour of bromine water disappeared immediately. Why?
The products of cracking contained unsaturated (hydrocarbons) / alkenes / C=C / ethane / reasonable name of alkene, which decolourised the bromine water immediately by addition reaction (2)
(II) The student then dropped more bromine water into the boiling tube until the brown colour of the bromine water persisted. After about 10 minutes, the brown colour disappeared. Why?
The products of cracking also contained saturated (hydrocarbons) / alkanes / methane/reasonable name or molecular formula of alkane, which decolourised the bromine water slowly by substitution reaction. (2)
3. The diagram below shows the set-up used in performing a microscale experiment. A drop of hydrochloric acid was added to the drop of chlorine bleach in a petri dish was immediately covered with is lid. Chlorine gas formed by the reaction between chlorine bleach and hydrochloric acid eventually filled up the whole set-up.