Chm 501
Practice Lab Quiz: Silicon

Instructions:  Circle the best answer for each question.

The Reagent Shelf.
These compounds are available as pure substances or in solution, as appropriate for your needs.
 
Acids  Bases  Boron  Carbon Halogens Hydrogen
H2SO4
H3PO4
HCl
HNO3
 

 

 Ca(OH)2
KOH
NaOH
 

 

 B(OH)3
B2O3
BF3
Na2B4O7.10 H2O
NaBH4
NaBO3.4 H2O 		 C(s) 
CaC2
CO 
CO2
Na2CO3
Na2CO3
NaHCO3		 Br2
Cl2
I2
KBr 
KI 
NaCl 		 CaH2
H2
LiAlH4
NaBH4
 

 

 
Metals, Metal Salts  Oxygen  Nitrogen  Phosphorus Silicon Sulfur
Cu
Cu(NO3)2
Mg
MgO
MnO2
Zn
Zn(NO3)2		 H2O
H2O2
Na2O
O2
O3
 

 

 KNO3
NaNO2
NH3(aq)
NH3(g)
 

 

 Ca3P2
H3PO3
H3PO4
P(red)
P4
P4O10

 

 Si
SiCl4
 
 
 
 
 

 

 H2S
FeS
Na2S
Na2SO3
NaHSO3
S8
SO2
SO3

Silicon

1. Which of the following is NOT a true statement about silicon?

A. Elemental silicon does not occur in nature.
B. Silicates include salts of SiO4-4 and (SiO3-2)n.
C. The earth's mantle consists of mostly silicate compounds.
D. Silicates are generally soluble in water.
E. Silicates consist of tetrahedral silicon atoms bonded to four oxygens.


2. Which of the following increases as a periodic trend from carbon to lead?  (More than one possible answer.)

A. covalent radius
B. first ionization potential
C. Pauling electronegativity
D. melting point
E. density
F. electrical conductivity
 
3. Which of the following is NOT an important use of SiO2?
A. building materials (concrete and bricks)
B. piezoelectric materials
C. laxative
D. anticaking agent
E. filtering water
F. abrasive
G. desiccant
 
4. What is the formula for the following silicate?
A. Si3O9-9       B. Si3O9-6        C. Si3O6-6        D. Si3O6        E. Si6O9-6


5. Which of the following is a silane?

A. SiH4 B. SiCl4 C. SiO2  D. Si(OH)4 E. none of these
6 and 7.  Reagent Shelf Question.  What two reagents did you use to prepare elemental silicon in the laboratory?
 
8. The structure of silicon is shown below.  How many silicon atoms are present in the unit cell?
A. four
B. six
C. eight
D. eighteen
E. none of the above
9. Olivine is a mineral that occurs with Mg+2 cations and orthosilicate anions.  What is the empirical formula of olivine?
A. Mg2SiO4
B. MgSiO4
C. Mg4SiO4
D. Mg2Si2O7
D. Mg3Si2O7


10. Which of the following statements regarding the 'silicate gardens' is FALSE?

A. Metal ions form insoluble silicate membranes around the crystal.
B. The silicate membrane around a crystal is semipermeable to water.
C. As the metal salt crystal dissolves, the ion concentration becomes higher inside the membrane.
D. The osmotic pressure causes water to pass out of the silicate membrane faster than into it.
E. The silicate membrane ruptures releasing the concentrated metal salt solution to the silicate solution.
F. After the silicate membrane has ruptured, new membrane formation is instantaneous.
G. The silicate membrane is often weakest at the top where it has just formed, so membrane rupture usually occurs there.

Answers:
 
1.  D
2.  A, E, F
3.  C
4.  B
5.  A
6/7  O2 + Mg
8.  C
9.  A
10. D