Assignement-1, Chemistry
Date: June 2016, Marks - 30
Name: ……………………………………………………………………………………….. Class ………………………
1 (a) The melting point of sodium chloride is 801 °C. The melting point of chlorine is –101 °C.
Explain, in terms of structure and bonding, the difference between the melting points of
these two substances.
[3]
(b) Explain why molten sodium chloride conducts electricity but solid sodium chloride does
not.
[1]
(c) Bromine is a liquid at room temperature.
(i) Draw a diagram to show the arrangement of the molecules in liquid bromine. [2]
(ii) A small amount of liquid bromine was placed in the bottom of a sealed flask. After thirty
minutes the brown colour of the bromine had spread throughout the flask.
Use the kinetic particle theory to explain these observations. [3]
(d) Bromine forms a variety of compounds with other halogens. Bromine reacts with
fluorine to form bromine(I) fluoride, BrF. [1]
2. A student set up the apparatus shown below.
Colourless fumes of hydrogen chloride are given off by the hydrochloric acid. Colourless
fumes of ammonia are given off by the aqueous ammonia.
(a) After a few seconds, white fumes were seen at point X in the tube. Name the compound
formed at point X.
[1]
(b) Use the kinetic particle theory to explain this observation.
[2]
(c) The student repeated the experiment using a solution of methylamine, CH3NH2, in place
of ammonia, NH3. The white fumes were seen at point Y in the tube, rather than at point X.
Explain this difference.
[2]
Shaikh Wahiduzzaman & Shafiqul Islam Patuwary, Chemistry Teacher, O/A Level, CISD
Assignement-1, Chemistry
Date: June 2016, Marks - 30
3. The diagram below shows an experiment in which steam was passed over hot iron filings.
The products of the reaction are iron oxide, Fe3O4, and a gas which burns with a blue flame.
(a) Write an equation, including state symbols, for the reaction and describe what you
would see as the iron reacts with the steam. [3]
(b) Describe how the observations would be different if the experiment was repeated using
each of the following two metals in place of the iron filings.
(i) magnesium
(ii) copper
[3]
4. This question is about the chemistry of the elements in Period 3 of the Periodic Table.
(a) Compare the reactions of sodium and of magnesium with cold water. In each case
identify the products formed.
[2]
(b) Draw electronic structures, including the charges, of the ions present in sodium oxide.
Hence deduce the formula for sodium oxide.
[2]
(c) Write an equation for the formation of aluminium oxide from its elements. [1]
(d) Pure sand is silicon(IV) oxide. It has a giant molecular structure similar to that of
diamond. Suggest two physical properties of silicon(IV) oxide. [2]
(e) Chlorine(VII) oxide, Cl2O7, has a simple molecular structure. Suggest one physical and
one chemical property of Cl2O7.
[2]
Shaikh Wahiduzzaman & Shafiqul Islam Patuwary, Chemistry Teacher, O/A Level, CISD