Reaction Engineering - GATE-CH Questions

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Reaction Kinetics

GATE-CH-1988-7-b-iv-cre-2mark

1988-7-b-iv-cre

Liquid \(A\) decomposes by first order kinetics in an isothermal batch reactor. Fifty percent of \(A\) is converted in 300 seconds. The time required for a conversion of 75 percent is

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

1989-7-i-b-cre

For the following reaction, the rate constant at 373 K is 0.5 per minute. \[ 0.5A + B \rightarrow C \] The overall order of the reaction is

GATE-CH-1992-2-c-cre-2mark

1992-2-c-cre

A gaseous reaction \(A\rightarrow 2B+C\) takes place isothermally in a constant pressure reactor. Starting with a gaseous mixture containing 50% \(A\) (rest inerts), the ratio of final to initial volume is found to be 1.6. The percentage conversion of \(A\) is

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

1992-8-a-cre

The conversion of a reactant, undergoing a first order reaction, at a time equal to three times the half life of the reaction is

GATE-CH-1999-2-14-cre-2mark

1999-2-14-cre

Consider the n\(^{th}\) order irreversible liquid phase reaction \(A \rightarrow B\). Which one of the following plots involving half-life of the reaction \((t_{1/2})\) and the initial reactant concentration \((C_{A0})\) gives a straight line plot?


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GATE-CH-2000-1-19-cre-1mark

2000-1-19-cre

The reaction \(A\rightarrow B\) is conducted in an isothermal batch reactor. If the conversion of \(A\) increases linearly with holding time, then the order of the reaction is

GATE-CH-2000-2-17-cre-2mark

2000-2-17-cre

The following half-life data are available for the irreversible liquid phase reaction, \[ A \rightarrow \text { Products} \] 

Initial concentration
(kmol/m3)
Half-life
(min)
2 2
8 1

The overall order of the reaction is

GATE-CH-2001-1-14-cre-1mark

2001-1-14-cre

The conversion for a second order, irreversible reaction (constant volume), \(A \stackrel {k_2}{\longrightarrow } B\), in batch mode is given by

GATE-CH-2001-2-17-cre-2mark

2001-2-17-cre

The first-order, gas phase reaction \(A \stackrel {k_1}{\rightarrow } 2B\) is conducted isothermally in batch mode. The rate of change of conversion with time is given by

GATE-CH-2004-73-cre-2mark

2004-73-cre

For an isothermal second order aqueous phase reaction \(A \rightarrow B\), the ratio of the time required for 90% conversion to the time required for 45% conversion is


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GATE-CH-2005-26-cre-1mark

2005-26-cre

For the liquid phase reaction \(A \rightarrow P\), in a series of experiments in a batch reactor, the half-life \(t_{1/2}\) was found to be inversely proportional to the square root of the initial concentration of \(A\). The order of the reaction is

GATE-CH-2006-16-cre-1mark

2006-16-cre

A first order reversible reaction \(A\xrightleftharpoons [k_2]{k_1} B\) occurs in a batch reactor. The exponential decay of the concentration of \(A\) has the time constant

GATE-CH-2009-14-cre-1mark

2009-14-cre

The half-life of a first order liquid phase reaction is 30 seconds. Then the rate constant, in min-1, is

GATE-CH-2012-19-cre-1mark

2012-19-cre

The half-life of an \(n^{\text {th}}\) order reaction in a batch reactor depends on

GATE-CH-2015-18-cre-1mark

2015-18-cre

For which reaction order, the half-life of the reactant is half of the full lifetime (time for 100% conversion) of the reactant?


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GATE-CH-2015-19-cre-1mark

2015-19-cre

An irreversible, homogeneous reaction \(A\rightarrow \text {products}\), has the rate expression: \[ \text {Rate} = \frac {2C_A^2+0.1C_A}{1+50C_A}, \qquad \text {where \(C_A\) is the concentration of \(A\).} \] \(C_A\) varies in the range 0.5 - 50 mol/m3.
For very high concentrations of \(A\), the reaction order tends to:

GATE-CH-2007-58-cre-2mark

2007-58-cre

The following rate-concentration data are calculated from experiment. Find the activation energy temperature (\(E/R\)) of the first order reaction.

\(d_p\) \(C_A\) \(-r_A\) \(T\)
1 20 1 480
2 40 2 480
2 40 3 500

GATE-CH-2014-37-cre-2mark

2014-37-cre

A homogeneous reaction (\(R\rightarrow P\)) occurs in a batch reactor. The conversion of the reactant \(R\) is 67% after 10 minutes and 80% after 20 minutes. The rate equation for this reaction is

GATE-CH-2001-14-cre-5mark

The concentration versus batch time data for a constant volume, isothermal batch reactor is given in the table below.

\(t\) (s) 0 30 60 90 120 150 180
\(C_A\) (kmol/m\(^3\)) 1.00 0.92 0.89 0.81 0.76 0.72 0.70

Assuming the reaction to be first order in \(A\), the best value of \(k\) by least squares regression is found to be = _______________ \(\times 10^{-3}\) s\(^{-1}\)

GATE-CH-BT-2016-48-cre-2mark

BT-2016-48-cre

Decimal reduction of bacterial spores is 23 min at 121oC and the death kinetics follow first order. One litre medium containing \(10^5\) spores per mL was sterilized for 10 min at 121oC in a batch sterilizer. The number of spores in the medium after sterilization (assuming destruction of spores in heating and cooling period is negligible) will be ____________\(\times 10^7\).

GATE-CH-BT-2018-48-cre-2mark

BT-2018-48-cre

Mammalian cells in active growth phase were seeded at a density of \(1\times 10^5\) cells/mL. After 72 hours, \(1\times 10^6\) cells/mL were obtained. The population double time of the cells in hours is (up to two decimal places) ____________

0700-3-cre-2mark

0700-3-cre

Consider the reaction \(A+2B\rightarrow R\). This reaction was carried out and the following initial-rate data were reported. Determine the overall order of reaction and the reaction rate constant.

Run No. \(C_{A0}\) (mol/litre) \(C_{B0}\) (mol/litre) Initial rate (mol/litre.s)
1 0.10 0.10 1.01
2 0.15 0.10 1.51
3 0.10 0.20 2.01


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Last Modified on: 01-May-2024

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