أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي
منتديات الأجيال التعليمية :: الملتقى الدراسي العام :: منتدى الامتحانات :: امتحانات الصف الثالث الثانوي
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أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي
من طرف حنين الصمت الثلاثاء 14 مايو 2013, 9:02 pm
أهم 100 سؤال فى مادة كيمياء لغات - الجزء السابع
Solutions
1) Calculate the number of moles in 44.8 liters of ammonia NH3 at (stp)
Solution
One mole occupies 22.4 liters
X moles occupies 44.8 liters
No. of moles = 2 moles
2) Find the volume of 0.1 moles of carbon dioxide at (stp)
Solution
One mole occupies 22.4 liters
0.1mole occupies X
Volume = = 2.24 liters
3) Find the number of liters of
oxygen result from thermal dissociation of 10.65 gm of sodium chlorate (
NaClO3) into sodium chloride and oxygen at (stp)
( Na = 23 , Cl = 35.5 , O = 16 )
according to this equation
2NaClO3 2NaCl + 3O2
Solution
One mole of NaClO3 = 23 + 35.5 + (3x16) = 106.5
2NaClO3 2NaCl + 3O2
2 moles of sod. Chlorate gives 3 moles of oxygen
2 x 106.5 gives 3 x 22.4 liters of oxygen
10.65 gives X liters of oxygen
volume of oxygen = 3.36 liters
4) Calculate th number of water molecules produced from the reaction of 0.1 gram of hydrogen with excess of oxygen.
Solution
H2 + 0.5O2 H2O
2 gm. 6.02 x 1023
0.1 x
Number of water molecules = 0.301 x 1023 molecules
5) Calculate the density of hydrogen gas (H2 ) given that atomic mass of hydrogen =1
Solution
The density =
The density = = 0.089 g/cm3
6) Find the concentration ( molarity )of 2 grams of NaOH dissolved in 500 ml of water
( Na=23, O=16, H=1)
Solution
Mass = mass of one mole X molarity X volume (in liter)
2= 40 X molarity X 0.5
Molarity = = 0.1 mol/liter
7) Caculate the mass of potassium hydroxide needed to prepare 100 ml of a 0.05 molar ( K=39, O=16, H=1)
Solution
Mass = mass of one mole X molarity X volume (in liter)
Mass = 56 X 1 X 0.05
Mass = 2.8 gm
Calculate the no. of chloride ions produced from dissolving 5385 gm. NaCl in waterSolution
Mass of 1 mole no. of atoms
58.5 6.02 x 1023
5.85 X
No. of chloride ions = = 0.602 x 1023 ions
9) Calculate the mass of silicon
carbide produced from the reaction of 18 gm. Of carbon with silicon
dioxide according to this equation
SiO2 + 3C SiC + 2CO ( Si = 28 , C = 12 )
Solution
SiO2 + 3C SiC + 2CO
3 x 12 28 + 12
36 40
18 x
The mass of silicon carbide = 20 gram
10) An iron oxide ore contains 40 % iron III oxide (Fe2O3) how many tons of these ore
needed to produce ton of iron ( Fe = 56 , O = 16)
Solution
Fe2O3 + 3CO 2Fe + 3CO2
( 2 x 56 + 3 x 16 ) 2 x 56
x 1 x 106
mass of iron III oxide = 1.43 x 106 gm = 1.428 tons
mass of ore = 3.57 tons
11) Find out the mass of sodium hydroxide found in 20 ml solution cosumed by titration
of 24 ml of 0.1 molar hydrochloric acid solution ( Na=23 , O=16 , H=1 )
Solution
HCl + NaOH NaCl + H2O
M1V1 M2V2
ــــــــــــــ = ـــــــــــــ
Ma Mb
=
M2 ( molarity of NaOH ) = = 0.12 mole/liter
Mass = mass of one mole x molarity x volume(in liters) = 40 x 0.12 x 0.020 = 0.096 gram
12) On oxidation of one gram of
magnetite ore ( Fe3O4 + impurities) 0.72 gram of Fe2O3 is formed
calculate the % of Fe3O4 in the ore ( Fe = 56 , O = 16)
Solution
2Fe3O4 + O2 3Fe2O3
2( 3 x 56 + 4 x 16 ) 3( 2 x 56 + 3 x 16 )
464 480
X 0.72
mass of magnetite = 0.696 gm
% of magnetite in the ore = 69.6 % ≈ 70%
13) Two grams sample of impure
NaCl was dissolved in water , excess of AgNO3 was added to
precipitate 3.8 gm of silver chloride calculate the % of NaCl in the
sample ( Na = 23 ,
Cl = 35.5 , Ag = 108 )
Solution
NaCl + AgNO3 AgCl + NaNO3
( 23 + 35.5 ) ( 108 + 35.5)
58.5 143.5
X 3.8
Mass of NaCl = = 1.55 gm.
% of NaCl = = 77.5 %
14) A mixture of NaCl and NaOH
its mas = 0.1 gm, with titrated with 10 ml of 0.1 molar HCl Calculate
the % of NaOH in the mixture
Solution
NaOH + HCl NaCl + H2O
1 mole 1 mole
No. of moles of HCl = molarity x volume in liter
= 0.1 x = 0.001 mol
No. of moles of NaOH = No. of moles of HCl = 0.001 mol
Mass = mass of one mole x molarity x volume(in liters)
Mass of NaOH = ( 23 + 16 +1) x 0.001 = 0.04 gram
% of NaOH = = 40 %
15) When 2.44 gm of hydrated
barium chloride strongly heated the mass of BaCl2 formed was = 2.08 ,
find out the % of water in the hydrated salt and find out molecular
formula of hydrated barium chloride ( Ba=137, Cl=35.5, O=16, H=1 )
Solution
BaCl2. xH2O BaCl2 + xH2O
2.44 2.08 0.36
Mass of water in this sample = 0.36 gm
% of water = =
% of water = = 14.75 %
One mole of BaCl2 = 137 + 2 x 35.5 = 208
BaCl2 combine with xH2O
2.08 0.36
208 x
Mass of water = = 36 gm
No. of water molecules = = 2
So chemical formula of hydrated barium chloride = BaCl2.2H2O
Scientific term
30. Amount of electricity needed to form equavelent weight of element during electrolysis
31. Galvanic cell is characterized by its reversible chemical reaction
32. Descending arrangement of elements according to their negative reduction potential
33. The standard electrode which has electric potential equals zero
34. The electrode at which oxidation process takes place in the electrochemical cells
35. Type of a chemical reaction where electrons transfere from one reactant to another
36. System in ehich chemical energy is converted to electric energy through redox reaction
37. A small size cell commonly used in hearing – aid watches
38. Cell where an spontaneous irreversible oxidation reaction takes
39. Redox reaction is forced to occur by using an external applied electric current
40. Positive pole at which reduction takes place in galvanic cell
Answer Scientific term
30. Faraday
31. Secondary cell
32. Electromotive series
33. Standard hydrogen electrode
34. Anode
35. Redox reaction
36. Galvanic cell
37. Mercury cell
38. Primary cell
39. Electrolysis
40. Cathode
حنين الصمت- مدير عام المنتدى
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عدد المساهمات : 5102
نقاط : 29201
تاريخ التسجيل : 08/09/2011
منتديات الأجيال التعليمية :: الملتقى الدراسي العام :: منتدى الامتحانات :: امتحانات الصف الثالث الثانوي
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