SSCC1703
UTM
UN1VERSITI TEKNOIOGI MALAYSIA
UNIVERSITI TEKNOLOGI MALAYSIA
FAKULTI SAINS
FINAL EXAMINATION
SEMESTER 1 SESSION 2016/2017
CODE
: SSCC1703
COURSE
: INORGANIC CHEMISTRY
LECTURER/S
: ASSOC. PROF. DR. RUSMIDAH ALI (C)
DR. SHEELA CHANDREN
PROGRAMMES
: 1SSCC & 1SSCA
DATE
: 5 JANUARY 2017
TIME DURATION : 3 HOURS
INSTRUCTION TO STUDENTS
1. This question paper consists of SECTION A and SECTION B.
2. Answer ALL questions in the answering booklet.
3. Start answering new question on a new page.
(THIS QUESTION PAPER CONSISTS OF 6 PRINTED PAGES INCLUDING THIS PAGE)
SSCC1703
SECTION A (20 MARKS)
1.
The graph below shows one of the trend of elements in the Periodic Table. Identify the
trend (Y) and name element X.
Atomic number
(2
marks)
2.
What is the starting material used in the steam reforming process? Outline the major
advantage and disadvantage of using this method to produce hydrogen.
(3 marks)
3a) Why are the elements in Group IA
(i) called alkali metal?
(ii) highly electropositive metals?
(2 marks)
b)
Using the data given in the table below, calculate the enthalpy of solution, AHsoi for
Mgl2 and Bal2. Which salt is more soluble in water?_______________________________
Lattice energy (kJ/mol), Hydration energy (kJ/mol),
Salt
Mgl2
Bal2
Alatt
Ahyd
+2314
+1841
-2505
-1887
(3 marks)
4a) Explain why B and A1 seem not reactive even though the E ° S r p (B = - 0.73 eV and
A1 = -1.67 ev)?
b) Why aluminium sulphate solution is acidic? Show the reaction to prove.
(2+2 marks)
5a) Write down one reaction to prepare Xe 0 3 . What is the molecular shape of xenon
trioxide, Xe 0 3 ?
b) Identify the oxidizing and reducing agents in the following redox reaction. Give reason.
XeF 4(s) + Pt(s) -» Xe(g) + PtF4(s)
(2 +4 marks)
2
SSCC1703
SECTION B (80 MARKS)
QUESTION 1 (20 MARKS)
a) Group IVA is the only group which contains all 3 major classifications of elements;
metal, metalloid and non-metal.
(i)
Name one element in this group that is a metal?
(ii)
Can the element in (i) conduct electricity and why?
( 1+ 2 marks)
b) Explain the following:
(i)
There is a significant difference in the melting point (m.p.) between silicon
(m.p. 1410°C) and lead (m.p. 328°C).
(ii)
Silicon forms one oxide, while lead forms three oxides.
(2+ 2 marks)
c) Acidification o f water glass (Na2SiC>3) will generally forms a salt, water and a white
precipitate. This white precipitate can only be dissolved in aqueous hydrofluoric acid
and aqueous sodium hydroxide. Identify the white precipitate and write the equation for
the acidification (eg. HC1) of water glass, and the dissolution of the white precipitate in
aqueous hydrofluoric acid and aqueous sodium hydroxide.
(4 marks)
d) (i)
(ii)
e) (i)
(ii)
Describe briefly how tin is obtained from cassiterite, SnC>2.
Two types o f amphoteric oxides can be formed from tin and one of it is black
tin. State the oxidation number of Sn in black tin and show the amphoteric
nature of black tin by giving the reaction of black tin in both acid and alkali.
(2+3 marks)
Lead forms three types of oxides. When lead is heated in air, what oxide is
formed?
Trilead tetraoxide, Pb30 4, is a type of lead oxide that is widely used in paint
industries. Give the use of this oxide in the paint industry and how can this
oxide be prepared?
(1+3 marks)
3
SSCC1703
QUESTION 2 (20 MARKS)
a) Give the chemical formula for the following terms:
(i)
Oxide of nitrogen that exists as dark blue liquid at room temperature.
(ii)
Solid allotrope of phosphorus that glows when exposed to air.
(iii)
Oxoacid of phosphorus with the common name of phosphonic acid.
( 1 + 1+ 1 marks)
b)
c)
Ammonia, NH3, and phosphine, PH3, are both hydrides of Group VA.
(i)
Which molecule is a Lewis acid? Explain your answer.
(ii)
Which hydride will be more stable in water? Explain your answer.
(iii)
If each hydride forms salts such as NH4CI and PH4CI, would you expect the
solution of the salts to be acidic or basic? Prove your answer by writing the
appropriate reactions.
(2+2+3 marks)
H3PO3 and H3PO4 are dibasic and tribasic phosphoric acid, respectively.
(i)
Draw the structure for both acids and circle the hydrogen that are responsible
for the dibasic and tribasic acid property of each acid.
(ii)
Which acid is a reducing agent? Why?
(iii)
H4P2O5
(iv)
Give one use of each acid.
is formed when H3PO3 undergoes dehydration. Show the mechanism
of the formation of H4P2O5.
(4+2+2+2 marks)
SSCC1703
QUESTION 3 (20 MARKS)
a) Explain the following statements
(i)Oxygen exists as oxygen molecule, 0 = 0 , while sulfur forms as Ss puckered
ring.
(ii)
H2O exists as liquid while H 2S as gas at room temperature
(2 + 2
marks)
b) By using molecular orbital theory (MOT), prove that O2 molecule is paramagnetic
while peroxide ion O 22”, is diamagnetic.
(3 marks)
c) Discuss on how O3 layer in the atmosphere prevent high energy UV from reaching the
earth. Give appropriate reaction to support your answer.
(3 marks)
d) Sulfur dioxide, S 0 2 is said to be one of a sources of air pollutant that resulting in
phenomenon of acid rain.
(i)
Calculate the oxidation state of S in SO2.
(ii)
Give two activities that can contribute SO2 in the atmosphere. Support your
answers with balanced chemical reactions.
(iii)
Write the reaction of SO2 and rain water. Draw the structure of the acid form.
State type of hybridization of S.
(iv)
Starting with S 0 3 ; describe the industrial preparation of sulphuric acid, H2SO4.
Write the equation of the reactions involved.
(1+4+3+2 marks)
QUESTION 4 (20 MARKS)
a) Name the following oxoacid of chlorine and arrange the acid strength in ascending
order.
(i)
(ii)
(iii)
(iv)
HOCIO2
HOCIO
HOCIO3
HOC 1
(l+ l+ l+ l+ l marks)
5
SSCC1703
b) Explain each o f the following observations.
(i)
(ii)
(iii)
Boiling point o f HF (MW= 20 g/mol) is 20°C but HI (81 g/mol) is -35°C.
HI cannot be prepared by treating Nal with sulfuric acid.
HF cannot be stored in glass bottle.
(1+2+2 marks)
c) You are given two test tubes containing chloride, Cl' ion and bromide, Br‘ ion
respectively. Briefly explain how you identify each ion.
(4 marks)
d) Draw the Lewis structures of CIO2 and CI2O7. Identify the oxidation number and
hybridization of Cl atom in each molecule, (valence electron: Cl=7, 0=6)
(6 marks)
End of paper
6