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

أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي 1

أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي 1

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

Cool

Calculate the no. of chloride ions produced from dissolving 5385 gm. NaCl in water

Solution

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

أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي 2

أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي 2

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 %

أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي 3

أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي 3

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

أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي 4

أهم 100 سؤال فى مراجعة مادة كيمياء لغات الجزء السابع ثالث ثانوي 4

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