Reaction Engineering - GATE-CH Questions

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Reaction Mechanism

0700-1-cre-1mark

0700-1-cre

Collision theory states that the rate constant \(k\) is proportional to

GATE-CH-1988-7-b-ii-cre-1mark

1988-7-b-ii-cre

In transition-state theory, the rate of the reaction is derived by assuming that the activated complex is in equilibrium with

GATE-CH-1989-7-i-a-cre-1mark

1989-7-i-a-cre

From the stoichiometry, one can say that the following reaction is non-elementary. \[ \ce {N2} + 3\ce {H2} \Leftrightarrow 2 \ce {NH3} \] The reason is

GATE-CH-1989-7-i-c-cre-2mark

1989-7-i-c-cre

The rate constant for a particular reaction becomes 100 times as large when the temperature is increased from 400 K to 500 K. Assuming that the transition state theory is valid, the value of \((E/R)\), i.e., the activation energy divided by the gas constant is:

GATE-CH-1990-7-iii-cre-2mark

1990-7-iii-cre

In a homogeneous gas phase reaction \(A + 2B \rightarrow R + S\) what is the relationship between \(r_{A}\) and \(r_{B}\):


[Index]



GATE-CH-1992-8-b-cre-2mark

1992-8-b

The units of frequency factor in Arrhenius equation

GATE-CH-1996-1-3-cre-1mark

1996-1-3-cre

From collision theory, the reaction rate constant is proportional to

GATE-CH-1998-1-20-cre-1mark

1998-1-20-cre

Molecularity of an elementary reaction \(P +Q \rightarrow R + S\) is

GATE-CH-1999-1-21-cre-1mark

1999-1-21-cre

Overall order of reaction for which the rate constant has units of (mol/litre)\(^{-3/2}\).s\(^{-1}\) is

GATE-CH-1999-1-22-cre-1mark

1999-1-22-cre

For the reaction \(A + B \rightarrow 2B + C\),


[Index]



GATE-CH-1999-2-15-cre-2mark

1999-2-15-cre

At a given value of \(E/R\) (ratio of activation energy and gas constant), the ratio of the rate constants at 500 K and 400 K is 2 if Arrhenius law is used. What will be this ratio if transition-state theory is used with the same value of \(E/R\)?

GATE-CH-2000-1-18-cre-1mark

2000-1-18-cre

The experimentally determined overall order for the reaction \[ A + B \rightarrow C + D \] is two. Then the

GATE-CH-2001-1-15-cre-1mark

2001-1-15-cre

The reaction rate constants at two different temperatures \(T_1\) and \(T_2\) are related by

GATE-CH-2003-21-cre-1mark

2003-21-cre

Find a mechanism that is consistent with the rate equation and the reaction given below: \[ 2A + B \rightarrow A_2B \quad \quad \quad -r_A = kC_AC_B \]

GATE-CH-2004-10-cre-1mark

2004-10-cre

The rate expression for the gaseous phase reaction CO + 2H2 \(\rightleftharpoons \) CH3OH is given by \[ r = k_1p^\alpha _{\text {CO}} p^\beta _{\text {H$_2$}} - k_2p^\gamma _{\text{CH$_3$OH}} \]  Which of the following is NOT possible?


[Index]



GATE-CH-2004-23-cre-1mark

2004-23-cre

The rate of ammonia synthesis for the reaction N2 + 3H2 \(\rightleftharpoons \) 2NH3 is given by \[ r = 0.8 p_{\text {N}_2}p_{\text {H}_2}^3-0.6p_{\text {NH}_3}^2 \] If the reaction is represented as, \(\displaystyle \frac {1}{2}\text {N}_2 + \frac {3}{2}\text {H}_2 \rightleftharpoons \text {NH}_3 \), the rate of ammonia synthesis is

GATE-CH-2005-25-cre-1mark

2005-25-cre

For the reaction \(2R + S \rightarrow T\), the rates of formation, \(r_R\), \(r_S\) and \(r_T\) of the substances \(R\), \(S\) and \(T\) respectively, are related by

GATE-CH-2005-27-cre-1mark

2005-27-cre

Which is the correct statement from the following statements on the Arrhenius model of the rate constant \(k = Ae^{-E/RT}\)?

GATE-CH-2005-67-cre-2mark

2005-67-cre

The rate expression for the reaction of \(A\) is given by \[ -r_A = \frac {k_1C_A^2}{1+k_2C_A^{1/2}} \] The units of \(k_1\) and \(k_2\) are, respectively,

GATE-CH-2015-17-cre-1mark

2015-17-cre

Which of the following can change if only the catalyst is changed for a reaction system?


[Index]



GATE-CH-2016-14-cre-1mark

2016-14-cre

For a non-catalytic homogeneous reaction \(A \rightarrow B\), the rate expression at 300 K is \[ -r_A  \quad (\text {mol.m$^{-3}$.s$^{-1}$})=\frac {10C_A}{1+5C_A} \] where \(C_A\) is the concentration of \(A\) (in mol/m3). Theoretically, the upper limit for the magnitude of the reaction rate (\(-r_A\) in mol.m\(^{-3}\).s-1, rounded off to the first decimal place) at 300 K is ____________

GATE-CH-2016-16-cre-1mark

2016-16-cre

Hydrogen iodide decomposes through the reaction 2HI \(\rightleftharpoons \) H2 + I2. The value of the universal gas constant \(R\) is 8.314 J.mol-1.K-1. The activation energy for the forward reaction is 184000 J/mol. The ratio (rounded off to the first decimal place) of the forward reaction rate at 600 K to that at 550 K is ____________

GATE-CH-1994-3-l-cre-1mark

1994-3-l-cre

If the rate of the irreversible reaction \(A + B \rightarrow 2C\) is \(kC_AC_B\), then the reaction is always elementary. (True / False)

GATE-CH-1994-3-o-cre-1mark

1994-3-o-cre

The mechanism for the decomposition of \(\ce {CH3CHO}\) into \(\ce {CH4}\) and \(\ce {CO}\) in the presence of \(\ce {I2}\) is \[ \begin {align*} \ce {CH3CHO} + \ce {I2} &\rightarrow \ce {CH3I} + \ce {HI} + \ce {CO}; \text { slow} \\
\ce {CH3I} + \ce {HI} &\rightarrow \ce {CH4} + \ce {I2}; \text { fast} \end {align*} \]
Then, the rate of disappearance of \(\ce {CH3CHO}\) is equal to \(kC_{\ce {CH3I}}C_{\ce {HI}}\) and \(\ce {HI}\) acts as a catalyst. (True / False)

GATE-CH-2006-49-cre-2mark

2006-49-cre

A drug tablet of mass \(M_0\) administered orally at time \(t = 0\), reaches the intestine at time \(t = \tau \) without losing any mass. From the intestine, the drug is absorbed into blood. The rate of absorption is found to be proportional to the mass of the drug in the intestine with the proportionality constant \(k\). Assuming no drug is lost from the blood, the total mass of the drug in the blood, \(M_b\), at time \(t > \tau \) is given by


[Index]



GATE-CH-2006-50-cre-2mark

2006-50-cre

The rate \(r\) at which an antiviral drug acts increases with its concentration in the blood, \(C\), according to the equation, \(r = \dfrac {kC}{C_{50}+C}\) where \(C_{50}\) is the concentration at which the rate is 50% of the maximum rate \(k\). Often, the concentration \(C_{90}\), when the rate is 90% of the maximum, is measured instead of \(C_{50}\). The rate equation then becomes

GATE-CH-2013-40-cre-2mark

2013-40-cre

The gas phase decomposition of azomethane to give ethane and nitrogen takes place according to the following sequence of elementary reactions. 

\[ \begin {align*} (\text {CH}_3)_2\text {N}_2 + (\text {CH}_3)_2\text {N}_2 &\stackrel {k_1}{\longrightarrow } (\text {CH}_3)_2\text {N}_2 + [(\text {CH}_3)_2\text {N}_2]^* \\ [(\text {CH}_3)_2\text {N}_2]^* + (\text {CH}_3)_2\text {N}_2 &\stackrel {k_2}{\longrightarrow } (\text {CH}_3)_2\text {N}_2 + (\text {CH}_3)_2\text {N}_2 \\ [(\text {CH}_3)_2\text {N}_2]^* &\stackrel {k_3}{\longrightarrow } \text {C}_2\text {H}_6 + \text {N}_2 \end {align*} \]

Using the pseudo-steady-state-approximation for \([(\text {CH}_3)_2\text {N}_2]^*\), the order with respect to azo-methane in the rate expression for the formation of ethane, in the limit of high concentrations of azomethane, is ____________

GATE-CH-1988-17-i-cre-6mark

1988-17-i-cre

The decomposition of \(\ce {N2O5}\) is postulated to occur by the following mechanism: \[ \begin {align*} \ce {N2O5 & <=>[k_1][k_2] NO2 + NO3^*} \\
\ce {NO3^*} &\stackrel {k_3}{\rightarrow } \ce {NO^*} + \ce {O2} \\
\ce {NO^*} + \ce {NO3^*} &\stackrel {k_4}{\rightarrow } 2\ce {NO2} \end {align*} \]
Using the steady state approximation, derive an expression for the rate of decomposition of \(\ce {N2O5}\).

GATE-CH-1990-17-i-cre-2mark

1990-17-i-cre

For a unimolecular gas phase reaction \(A\rightarrow \) Products, the reaction mechanism is given by \(r = \dfrac {k_1k_3[A]^2}{k_2[A]+k_3}\). What would be the order of this reaction at very high and very low pressures?

GATE-CH-1992-8-d-cre-2mark

1992-8-d-cre

In a first-order reaction \(A\rightarrow \text {Products}\), the reaction rate becomes slower as it proceeds, because the concentration of \(A\) ––––- , and the rate is ––––-


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Last Modified on: 01-May-2024

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