Controle 5 Spinelle .pdf


Nom original: Controle 5_Spinelle.pdfTitre: UNIVERSITE HASSAN II – MOHAMMEDIAAuteur: said

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Name: ………………………………………………………………………………
UNIVERSITE HASSAN II – MOHAMMEDIA
FACULTE DES SCIENCES BEN M'SIK
CASABLANCA
DÉPARTEMENT DE CHIMIE
-----------MASTER GENIE DE MATERIAUX
Module Stratégie de synthèse des matériaux
Semestre 1
Pr. Said BENMOKHTAR

Promotion 2012-2014

Exam N°5 ( 20 min )
Q1 : Inspired by the presentation made by Imane Daou

A- Conventional solid state reaction
1) Write the reaction at interface for the synthesis of MgAl2O4 from the reactants, MgO and
Al2O3 :
(i) MgO/MgAl2O4: Mg2+ at the interface of MgO/MgAl2O4 diffused into MgAl2O4
......................................................................................................................................................
(ii) MgAl2O4/Al2O3: Al3+ at the interface of MgAl2O4/Al2O3 diffused into MgAl2O4
......................................................................................................................................................

B- Microwave heating
Oxides were used as reactants for the preparation of the compound MgAl2O4. Stoichiometric
amounts of the required high purity reactants were ground well in each case and exposed to
microwave irradiation for about 10 min in silica crucibles kept inside a domestic microwave
oven (2×45 GHz, 980 W) operating at the highest power level.
1) Discuss the meaning of the text.
......................................................................................................................................................
......................................................................................................................................................
......................................................................................................................................................
2) A microwave has a wavelength of 2mm. Find the amount of energy in Joules of one photon
of this microwave.
......................................................................................................................................................
3) Microwaves have longer wavelengths than ultraviolet-rays. Which of the following
statements is true?
[a] Microwaves have lower frequencies than UV-rays.
[b] Microwaves travel slower than UV-rays.
[c] Microwaves are higher energy than UV-rays.
[d] Microwaves have a larger amplitude than UV-rays.
[e] None of the above statements is true.
4) The energy of a photon of light is……………..proportional to its frequency and ……….
proportional to its wavelength.
[a] directly, directly
[b] inversely, inversely
[c] directly, inversely
[d] inversely, directly
[e] indirectly, not
FSB_ MASTER GENIE DE MATERIAUX

Année Universitaire 2012-2013

Name: ………………………………………………………………………………

5) Complete the binary phase diagram: MgO-Al2O3

6) Considering the different types of interstices (tetrahedral and octahedral holes in such a
CFC lattice, draw the structure of this spinel MgAl2O4.

(I)
(II

(II
(I)

(II)

(I)
(II
(I)

FSB_ MASTER GENIE DE MATERIAUX

(I)
(II

Année Universitaire 2012-2013


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