209737
Descripción
Test por Emine Afiyet Fra, actualizado hace más de 1 año
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Creado por Emine Afiyet Fra
hace más de 11 años
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Pregunta 1
Pregunta
Which statement is true about chemical reactions at equilibrium?
Respuesta
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The forward and backward reactions proceed at equal rates
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The forward and backward reactions have stopped
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The concentrations of the reactants and products are equal
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The forward reaction is exothermic
Pregunta 2
Pregunta
Chemical equilibrium is referred to as dynamic because, at equilibrium, the...
Respuesta
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equilibrium constant changes
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reactants and products keep reacting
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rates of the forward and backward reactions change
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concentrations of the reactants and products continue to change
Pregunta 3
Pregunta
What is the equilibrium expression for the reaction: N2 + 3H2 --> 2NH3 (all in the gaseous state)?
Respuesta
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[NH3]^2/[N2][H2]^3
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2[NH3]/3[N2][H2]
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[NH3]/[N2][H2]
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2[NH3]/[N2][H2]
Pregunta 4
Pregunta
For a reaction which goes to completion, the equilibrium constant, Kc, is:
Respuesta
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more than 1 (Kc >>1)
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less than 1 (Kc
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= 1
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= 0
Pregunta 5
Pregunta
The equilibrium constant for the reaction below is 1.0 x 10^-14 at 25oC and 2.1 x 10^-14 at 35oC. What can be concluded from this information?
2H2O (l) H3O+ (aq) + OH- (aq)
Respuesta
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The ionization of water is endothermic
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[H3O+] decreases as the temperature is raised
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Water is a stronger electrolyte at 25oC
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[H3O+] is greater than [OH+] at 35oC
Pregunta 6
Pregunta
Ethanol is manufactured from ethene using the reaction:
C2H4 + H2O C2H5OH (Delta-H = -46 KJ)
Which conditions favour the highest yield of ethanol?
Respuesta
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High pressure and low temperature
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High pressure and high temperature
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Low pressure and low temperature
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Low pressure and high temperature
Pregunta 7
Pregunta
N2O4 and NO2 produce an equilibrium mixture according to the equation:
N2O4 2NO2 (Delta-H = 57.2 KJ/mol)
An increase in the equilibrium concentration of NO2 can be produced by increasing which of the factors below?
1) Pressure 2) Temperature
Respuesta
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1 only
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2 only
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both 1 and 2
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neither 1 or 2
Pregunta 8
Pregunta
Which changes will increase the amount of SO3 (g) at equilibrium?
2SO2 + O2 2SO3 (Delta-H = -197KJ)
1) increasing temperature 2) decreasing volume 3) adding a catalyst
Respuesta
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1 only
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2 only
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1 and 3 only
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1, 2 and 3
Pregunta 9
Pregunta
For the reaction N2 + 3H2 2NH3 (Delta-H = -92 KJ)
What conditions will produce the highest percentage of NH3 at equilibrium?
Respuesta
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High pressure and high temperature
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High pressure and low temperature
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Low pressure and high temperature
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Low pressure and low temperature
Pregunta 10
Pregunta
Hydrogen and iodine react in a closed vessel to form hydrogen iodide.
H2 + I2 2HI
at 350oC, Kc = 60
at 445oC, Kc = 47
Respuesta
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Increased temperature as the forward reaction is exothermic, and increased pressure as there are two gaseous reactants and only one gaseous product
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Increased temperature as the forward reaction is endothermic, and pressure has no effect as there are equal amounts, in mol, of gaseous reactants and products
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Decreased temperature as the forward reaction is exothermic, and decreased pressure as there are 2 moles of gaseous product but only 1 mole of each gaseous reactant
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Decreased temperature as the forward reaction is exothermic, and pressure has no effect as there are equal amounts, in mol, of gaseous reactants and products
Pregunta 11
Pregunta
An increase in temperature increases the amount of chlorine present in the following equilibrium.
PCL5 (s) PCL3 (l) + CL2 (g)
What is the best explanation for this?
Respuesta
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The higher temperature increases the rate of the forward reaction only.
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The higher temperature increases the rate of the reverse reaction only
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The higher temperature increases the rate of both reactions but the reverse reaction is affected more than the forward
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The higher temperature increases the rate of both reactions but the forward reaction is affected more than the reverse
Pregunta 12
Pregunta
The reaction between sulfur dioxide and oxygen (the contact process) occurs according to the equation below: 2SO2 + O2 2SO3 (Delta-H = -197)
A higher equilibrium concentration of SO3 will be produced by all of the following changes in a reaction conditions except...
Respuesta
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increasing pressure
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adding more O2
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adding a catalyst
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decreasing the temperature
Pregunta 13
Pregunta
The reaction between methane and hydrogen sulfide is represented by the equation below:
CH4 + 2H2S CS2 + 4H2
What is the equilibrium expression for this reaction?
Respuesta
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[CS2][H2]/[CH4][H2S]
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4[CS2][H2]/2[CH4][H2S]
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[CS2] 4[H2]/[CH4] + 2[H2S]
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[CS2][H2]^4/[CH4][H2S]^2
Pregunta 14
Pregunta
At 35oC, Kc = 1.6 x 10^-5 mol/dm^3 for the reaction:
2NOCL 2NO + Cl2
Which relationship must be correct at equilibrium?
Respuesta
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[NO] = [NOCl]
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2[NO] = [Cl2]
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[NOCl]
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[NO]
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