Online Exam - Chem2 | Me.Committee
#لجنة_الهندسة_الميكانيكية #الفريق_الأكاديمي. . . R = 8. 314 J/mol >>>> K =0. 0821 L. Atm/mol. K
- 1.Constants >>> R = 8.314 J/mol >>>> K =0.0821 L.atm/mol.k ... Q1) The equilibrium constant for the following reaction is 5.0 × 108 at 25° C , the value of Δ G (KJ/mol) for this reaction is : N2(g) + 3H(g) ⇆ 2NH3(g)
- A.
22
- B.
-4.2
- C.
-25
- D.
-50
- 2.Q2) The rate constant (s−1) of a first order that has half life of (225 s) is
- A.
0.693
- B.
3.08 × 10-3
- C.
1.25
- D.
12.5
- 3.Q3) As a temperature of a reaction is increased , the rate of the reaction increases because :
- A.
Reactant molecules collide less frequently
- B.
Activation energy is lowered
- C.
Reactant molecules collide more frequently and with greater energy per collision
- D.
Reactant molecules collide less frequently and with greater energy per collision
- 4.Q4) why is potassium bromide (KBr) is insoluble in carbon tetrachloride (CCl4) ?
- A.
Both KBr and (CCl4) are non polar
- B.
Solvent -solvent interaction are strong
- C.
Solute -solvent interaction are strong
- D.
Solute -solvent interaction are weak
- 5.Q4) In general , as temperature increases , reaction rate
- A.
Increases , if the reaction is exothermic
- B.
Increases , if the reaction is endothermic
- C.
Increases , regardless whether the reaction is endothermic or exothermic
- D.
Stays the same if the reaction is first order
- 6.Q5) For the elementary reaction NO3 + CO → NO2 + CO2 the molecularity and the rate law of the reaction are :
- A.
2, K [NO3] [CO]
- B.
4, K [NO3] [CO] [NO2] [CO2]
- C.
2, K [NO2] [CO2]
- D.
2, K [NO3] [CO] / [NO2] [CO2]
- 7.The reaction A(aq) → B(aq) is first order in [A] . A solution is prepared with [A] = 1.22 M . The following data is obtained as the reaction proceeds . The rate constant (s−1) for this reaction is : Time (s) 0.0 6.0 12.0 18.0 [A] (M) 1.22 0.61 0.31 0.15
- A.
0.23
- B.
1.0
- C.
0.17
- D.
0.12
- 8.Q8) A compound decomposes by a first-order process . If 25.0% of the compound decomposes in 60.0 minutes , the half-life of the compound is :
- A.
65
- B.
120
- C.
145
- D.
180
- 9.Q9) which of the units below are appropriate for a second-order reaction rate constant
- A.
Ms−1
- B.
S−1
- C.
Mol/L
- D.
M−1 s−1
- 10.Q10) A certain second order reaction is 60% complete in 25 minutes . calculate the rate constant (K) of this reaction :
- A.
6.0 × 10^-2
- B.
2.7 × 10^-2
- C.
3.3 × 10^-4
- D.
2.1 × 10^-2
- 11.Q11) A sealed 1.0 L flask is charged with 0.500 mol of I2 and 0.500 mol of Br2 . An equilibrium reaction ensues : I2 (g) + Br2 (g) ⇆ 2 IBr (g) when te container contents achieve equilibrium , the flask contains 0.84 mol of IBr . Keq is:
- A.
11
- B.
4.0
- C.
110
- D.
6.1
- 12.Q12) which is true at equilibrium ?
- A.
The limiting reagent has been consumed
- B.
The rates of the forward and reverse reactions are equal
- C.
The rate constants of the forward and reverse reactions are equal
- D.
The value of the equilibrium constant is 1
- 13.Q13) Given the following reaction at equilibrium at 450.0° C : CaCO3 (s) ⇆ CaO (s) + CO2 If pCO2 = 0.0160 atm , then Kc =
- A.
0.0160
- B.
0.0821
- C.
7.23
- D.
2.7 × 10-4
- 14.Q14) The following data were obtained for the reaction BF3 + NH3 → F3BNH3 Exp [BF3] [NH3] initial rate 1 0.25 0.25 0.213 2 0.25 0.125 0.1065 3 0.50 0.125 0.1065 the rate law of the reaction is :
- A.
K [NH3]
- B.
K [BF3]
- C.
K [BF3] [NH3]
- D.
K [NH3]^5
- 15.Q15) For the previous question , what is the rate when [BF3] =( 0. 10) , [NH3]= 0.50 M ?
- A.
0.426
- B.
0.50
- C.
0.852
- D.
1.0
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