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Chemical Engineering

The order of a reaction:

Molecularity of a reaction step:

The rate constant of a reaction has units of s to the minus one. The reaction is:

The half-life of a first-order reaction:

A plot of the natural logarithm of concentration against time gives a straight line. The reaction is:

In the Arrhenius equation, a plot of ln k against the reciprocal of absolute temperature has a slope of:

A reaction with a high activation energy will be:

The difference between the activation energies of the forward and reverse reactions equals the:

A catalyst increases the rate of a reversible reaction by:

For the reaction 2A + B gives 3C, the relationship between the rates is:

Raising the pressure on a gas-phase equilibrium shifts it towards:

For an exothermic reversible reaction, raising the temperature will:

Adding an inert gas to a gas-phase equilibrium at constant volume will:

The volume occupied by one kilomole of an ideal gas at 0 degrees Celsius and 1 atmosphere is:

A compressibility factor of 0.7 for a gas indicates that:

The generalised compressibility chart is useful because Z is approximately the same for all gases at the same:

In the van der Waals equation, the constant b corrects for:

For a system of one component existing as two phases in equilibrium, the number of degrees of freedom is:

At the triple point of a pure substance, the number of degrees of freedom is:

Above its critical temperature, a gas:

Raoult's law states that the partial pressure of a component above an ideal solution equals:

Relative volatility of two components in a mixture equals one. This means that:

An azeotropic mixture is one in which:

Henry's law is most applicable to:

On a temperature-composition diagram at constant pressure, the upper curve represents the:

The Clausius-Clapeyron equation shows that a plot of the logarithm of vapour pressure against the reciprocal of absolute temperature is:

The general material balance equation is:

Which balance is always valid even when a chemical reaction occurs?

Element balances are often preferred for combustion calculations because:

The limiting reactant in a reaction is the one that:

Percentage excess air in a combustion calculation is based on:

In combustion calculations, the number of moles of nitrogen accompanying each mole of oxygen from air is:

An Orsat analysis of flue gas reports the composition on:

Nitrogen is commonly used as a tie component in combustion balances because it:

In a process with recycle, the overall conversion is:

When writing an overall balance around a process containing a recycle loop:

A purge stream is required in a recycle loop in order to:

At steady state in a recycle loop with a purge, the rate at which inert enters in the fresh feed equals the rate at which it:

A degrees of freedom analysis gives a value of plus two for a flowsheet. This means the problem is:

For a steady-flow process with no shaft work and negligible kinetic and potential energy changes, the energy balance reduces to:

Which of the following is a path function rather than a state function?

The standard heat of formation of oxygen gas at 25 degrees Celsius is:

The standard heat of reaction is calculated from formation enthalpies as:

An exothermic reaction is characterised by:

The gross calorific value of a fuel differs from the net value by:

Hess's law allows the heat of a reaction to be calculated because enthalpy change is:

Kirchhoff's equation is used to:

The adiabatic flame temperature of a fuel is reduced by:

In a reactor energy balance using the heat of reaction method, the hypothetical path taken is:

For an ideal gas, the relationship between the two heat capacities is:

The latent heat of vaporisation of water at 100 degrees Celsius is approximately:

In solving a combined material and energy balance problem, the correct order is to:

The distinction between a unit operation and a unit process is that a unit process involves:

In industrial nitration using mixed acid, the function of the sulphuric acid is to:

The greatest hazard associated with industrial nitration is:

The catalyst used in the contact process for the vapour-phase oxidation of sulphur dioxide is:

Ethylene dichloride is an important industrial chemical chiefly because it is the route to:

Industrial hydrogenation of vegetable oils is carried out principally in order to:

The catalyst normally used in the hydrogenation of edible oils is:

The progress of oil hydrogenation is commonly monitored by measuring the:

A recognised health concern arising from the partial hydrogenation of oils is the formation of:

Saponification is the:

In the enzymatic hydrolysis of starch to dextrose, the enzyme used for the initial liquefaction step is:

Which type of polymerization eliminates a small molecule such as water during the reaction?

Which method of polymerization gives excellent heat control and a granular product that is easily separated, and is the standard route for PVC?

Unsteady-state behaviour of a well-mixed stirred tank is described mathematically by:

Partial differential equations arise in process modelling when:

An empirical or black box model is characterised by the fact that it:

A lumped parameter model assumes that:

Which numerical method is the standard workhorse for solving initial value ordinary differential equations?

The Newton-Raphson method is used to solve:

A stiff system of differential equations is one in which:

Verification of a process model asks whether:

In the sequential modular approach to flowsheet simulation:

The equation-oriented approach to simulation is particularly advantageous for:

A steady-state material balance on a flowsheet without reaction gives rise to:

The principal reason for using simulation rather than experimenting on the plant is that simulation:

A model in which random variation is deliberately included, as in residence time distribution analysis, is described as:

A reaction is thermodynamically spontaneous at a given temperature and pressure when:

A reaction that is exothermic and accompanied by an increase in entropy is:

The relationship between the standard Gibbs energy change and the equilibrium constant is:

In the equilibrium expression for the decomposition of calcium carbonate to calcium oxide and carbon dioxide, K equals:

The equilibrium constant of a reaction depends on:

According to the van 't Hoff equation, raising the temperature of an exothermic reversible reaction will:

Increasing the total pressure on the gas-phase reaction N2 + 3H2 giving 2NH3 will:

Adding an inert gas at constant total pressure to a gas-phase equilibrium with delta n positive will:

A catalyst added to a reversible reaction at equilibrium will:

The criterion for phase equilibrium of a species distributed between two phases is equality of its:

Absolute entropies of substances can be tabulated because:

The fact that diamond does not convert to graphite at room temperature despite a negative Gibbs energy change illustrates that:

Continuously removing a product from a reacting mixture, as in reactive distillation, allows:

For a throttling process through a valve, the property that remains constant is:

The first law of thermodynamics establishes:

For a reversible adiabatic process in an ideal gas:

The Kelvin-Planck statement of the second law asserts that no cyclic device can:

A Carnot engine operates between 600 K and 300 K. Its maximum possible efficiency is:

According to the Carnot principles, the efficiency of a reversible engine depends on:

Entropy generation in a process is:

Wet steam at a given pressure has a dryness fraction of 0.8. Its enthalpy is found from:

The isentropic efficiency of a compressor is defined as:

The work required to compress a gas is least when the compression is:

For minimum total work in a two-stage compressor with perfect intercooling, the intermediate pressure should equal:

Intercooling between the stages of an air compressor is used chiefly to:

The volumetric efficiency of a reciprocating compressor decreases when:

Maxwell relations are useful in thermodynamics because they:

A residual property is defined as the difference between the real value and the:

The Joule-Thomson coefficient of an ideal gas is:

Hydrogen and helium warm rather than cool when throttled at room temperature because:

At the critical point of a pure substance, the critical isotherm on a P-V diagram has:

The chemical potential of a species is identical to its:

The Gibbs-Duhem equation is used in practice to:

For an ideal solution, the enthalpy change on mixing is:

The fugacity coefficient of a gas approaches unity as:

Which activity coefficient model is used to predict behaviour from group contributions when no experimental data are available?

Superheating the steam entering a turbine in a Rankine cycle:

A combined cycle power plant achieves high efficiency by:

Trouton's rule states that for many liquids the ratio of the latent heat of vaporisation to the normal boiling point is about:

For a reaction of positive order, the reactor volume required for a given conversion is:

The design equation for a continuous stirred tank reactor is:

A series of equal-sized CSTRs behaves increasingly like a plug flow reactor as:

In a series reaction A giving B giving C where B is the desired product:

For two parallel reactions in which the desired product is formed by the higher-order reaction, selectivity is improved by:

The residence time distribution of a reactor is measured experimentally by:

The variance of the residence time distribution of an ideal plug flow reactor is:

Multiple steady states can occur in a CSTR carrying out an exothermic reaction because:

In a heterogeneous catalytic reaction, which sequence of steps is correct? out

Chemisorption differs from physisorption in that chemisorption:

An effectiveness factor close to unity for a catalyst pellet indicates that:

Under strong pore diffusion control, the apparent activation energy of a catalytic reaction is:

Loss of catalyst activity caused by the thermal growth of crystallites and loss of surface area is called:

For an ideal gas, the difference between the heat capacities at constant pressure and constant volume is:

The ratio of heat capacities for a diatomic ideal gas is approximately:

A mean heat capacity quoted for the range 25 to 200 degrees Celsius:

Hess's law of constant heat summation follows directly from the fact that enthalpy is:

Kirchhoff's law relates the heat of reaction at two temperatures through the:

The heat of solution of a substance must always be quoted together with:

Dissolving ammonium nitrate in water produces a marked cooling effect because the dissolution is:

Concentrated sulphuric acid should always be added to water rather than water to acid because:

The heat of mixing of two liquids forming an ideal solution is:

Pressure has only a small effect on the heat of reaction for gas-phase reactions because:

A bomb calorimeter measures the heat of combustion at constant:

If a combustion reaction produces a decrease of two moles of gas, the relationship between the enthalpy and internal energy changes is:

Kopp's rule is used to estimate the:

The coefficient of performance of a heat pump exceeds that of a refrigerator operating between the same temperatures by:

The Carnot coefficient of performance of a refrigerator operating between 250 K and 300 K is:

In the vapour compression refrigeration cycle, the expansion device is:

The pressure-enthalpy diagram is preferred for analysing refrigeration cycles because:

Subcooling the liquid refrigerant leaving the condenser:

One tonne of refrigeration is equal to:

Chlorofluorocarbon refrigerants were phased out under the Montreal Protocol because they:

Ammonia remains the preferred refrigerant in large industrial plants despite its toxicity because it has:

In an absorption refrigeration system, the component that replaces the compressor of a vapour compression system is the:

A lithium bromide-water absorption system cannot produce temperatures below 0 degrees Celsius because:

The coefficient of performance of a single-effect absorption chiller is typically about:

Adsorption refrigeration systems require two adsorbent beds because:

In the Claude liquefaction process, the improvement over the Linde process is that:

A fluid is defined as a substance that

An ideal fluid is one which is

The SI unit of dynamic viscosity is

One poise is equal to

With an increase in temperature, the viscosity of a liquid and that of a gas respectively

A fluid whose apparent viscosity decreases with increasing shear rate is called

Toothpaste and drilling mud, which do not flow until a certain minimum shear stress is exceeded, are examples of

A fluid whose apparent viscosity decreases with time at a constant rate of shear is

Kinematic viscosity is defined as

The excess pressure inside a soap bubble of radius R and surface tension sigma is

Capillary rise in a small vertical tube is

Pascal's law states that the pressure at a point in a fluid at rest

For a U-tube manometer with manometric fluid of density rho-m, process fluid of density rho and reading R, the pressure difference is

The centre of pressure on a plane surface submerged in a liquid always lies

A floating body is in stable equilibrium when

In steady flow, streamlines, pathlines and streaklines are

For laminar flow in a circular pipe, the ratio of maximum to average velocity is

According to the Hagen-Poiseuille equation, for a fixed pressure drop the volumetric flow rate through a pipe varies as

The velocity potential function exists only when the flow is

The stream function is defined for

Boundary layer separation occurs because of

Bernoulli's equation in its classical form is NOT applicable when

The kinetic energy correction factor for fully developed laminar flow in a pipe is

Compressibility effects may normally be neglected when the Mach number is below about

In a converging-diverging nozzle operating with supersonic exit flow, sonic velocity is reached

According to the Buckingham pi theorem, a problem involving 7 variables and 3 fundamental dimensions can be described by

The Darcy friction factor is related to the Fanning friction factor by

For laminar flow in a pipe, the friction factor depends on

In fully developed rough-pipe turbulent flow, the friction factor is

The equivalent diameter for flow through an annulus of outer diameter Do and inner diameter Di is

The loss coefficient K for a pipe discharging into a large reservoir is approximately

Which valve, when fully open, offers the least resistance to flow?

In a venturi meter compared with an orifice meter of the same throat ratio, the permanent pressure loss is

In a head-type flow meter, the flow rate is proportional to

A rotameter is classified as a

A Pitot tube is used to measure

If the speed of a centrifugal pump is doubled, the power required changes by a factor of

Cavitation in a centrifugal pump can be avoided by ensuring that

In a fully baffled agitated vessel operating in the turbulent regime, the power number is

The sphericity of a cube is approximately

In the Tyler standard screen series, successive screen apertures are in the ratio of

A material described as minus 14 plus 20 mesh is one which

Rittinger's law of crushing states that the energy required is proportional to

Kick's law is most applicable to

The Bond work index is defined as the energy required to reduce a very large feed to a product in which 80 per cent passes

If a ball mill is operated at or above its critical speed

The angle of nip in a roll crusher must not exceed

Which of the following mills produces an ultrafine product with essentially no moving parts in the grinding zone?

Compared with dry grinding, wet grinding generally

Closed-circuit grinding is preferred to open-circuit grinding because it

A bucket elevator is used primarily for

In dilute-phase pneumatic conveying, the solids are

Screening separates particles on the basis of

The effectiveness of a screen based on the undersize is given by

As the feed rate to a screen is increased, its capacity and effectiveness respectively

Blinding of a screen refers to

In a differential screen analysis, the number of particles per unit mass in a size interval varies as

The volume-surface or Sauter mean diameter is calculated as

Elutriation separates particles on the basis of

Froth flotation separates minerals principally by differences in

In froth flotation, the reagent whose function is to make the mineral surface hydrophobic is the

Copper sulphate added to a flotation circuit to make sphalerite respond to a xanthate collector acts as

Jigging separates particles principally on the basis of

Electrostatic separation of beach sands exploits differences in

Compared with free settling, hindered settling gives

According to Stokes' law, the terminal settling velocity of a small spherical particle is proportional to

Stokes' law for settling is valid when the particle Reynolds number is

In the Newton's law region of settling, the drag coefficient is approximately

The purpose of adding alum to a dilute suspension before sedimentation is to

In a continuous thickener, the required cross-sectional area is determined by

At the minimum fluidization velocity, the pressure drop across the bed equals

As the fluid velocity is increased beyond the minimum fluidization velocity, the pressure drop across the bed

The Ergun equation for flow through a packed bed contains

Gas-solid fluidization in which the gas passes through the bed as bubbles within a dense emulsion phase is called

The upper limit of the operating velocity range for a fluidized bed is set by

In constant-pressure filtration, a plot of t/V against V yields a straight line whose slope is proportional to

For a compressible filter cake, doubling the applied pressure difference

The correct sequence of zones encountered by a point on the surface of a rotary drum vacuum filter during one revolution is

The design equation for an ideal CSTR is

For a reaction of positive order, the volume of a PFR compared with that of a CSTR achieving the same conversion is

A CSTR is preferred over a PFR at low conversion for

Space time is defined as

Space time equals the mean residence time only when

For a gas-phase reaction A gives 2B carried out at constant temperature and pressure with pure A fed, the value of epsilon is

For N equal-sized CSTRs in series carrying out a first-order reaction, the exit concentration ratio is

As the number of equal CSTRs in series is increased at a fixed total volume, the conversion

In a series of reactors, the conversion used in the design equation for the second reactor is measured

The rate of reaction for a fluid-solid catalytic reaction is most commonly expressed per unit

A plug flow reactor is conceptually equivalent to

A fluidized bed reactor is preferred over a fixed bed reactor mainly when

For a batch reactor operating at constant volume, the design equation reduces to

The order of a reaction

For which reaction order is the half-life independent of the initial concentration?

A plot of 1/Cₐ against time gives a straight line. The reaction is

The rate constant of a reaction has units of s^-1. The reaction is

In the Arrhenius equation, a plot of ln k against 1/T gives a straight line whose slope equals

A reaction with a high activation energy is

For a gas-phase reaction with epsilon greater than zero carried out at constant temperature and pressure, the concentration of reactant A

For a first-order liquid-phase reaction in a CSTR, the conversion is given by

If the space time of a first-order PFR is doubled, the conversion

The correct order of steps in the isothermal reactor design algorithm is

Pressure drop in a reactor is an important design consideration for

Increasing the catalyst particle size in a packed bed reactor will

A catalyst increases the rate of a reaction by

In the integral method of analysing rate data, one

The differential method of rate-data analysis determines the reaction order from

The main disadvantage of the differential method compared with the integral method is that it

When reactant B is present in very large excess, the observed kinetics are described as

In a differential reactor, the conversion across the catalyst bed is deliberately kept

Which laboratory reactor allows the reaction rate to be obtained directly at steady state without any integration?

Selectivity in a multiple-reaction system is defined as

For the parallel reactions A to D (desired, second order in A) and A to U (undesired, first order in A), the desired product is favoured by

A semi-batch reactor in which one reactant is added slowly to the other is particularly useful for

If the desired reaction has a higher activation energy than the undesired reaction, selectivity is improved by operating at

For the series reaction A to B to C with first-order steps, the concentration of B

For maximising the yield of the intermediate B in the series reaction A to B to C

When several reactions occur simultaneously, the mole balances are most conveniently written in terms of

The pseudo-steady-state hypothesis assumes that

In the Michaelis-Menten equation, the constant Kₘ represents

At substrate concentrations far above Kₘ, an enzyme-catalysed reaction is

A Lineweaver-Burk plot is a plot of

Competitive inhibition of an enzyme is characterised by

In a chemostat operating at steady state, the specific growth rate of the cells equals

Washout occurs in a chemostat when

For an adiabatic reactor, the relation between temperature and conversion is

For an exothermic reversible reaction, the equilibrium conversion

Interstage cooling between catalyst beds in an exothermic reversible reaction is used to

When the heat generation curve and heat removal line for a CSTR intersect at three points, the middle steady state is

Parametric sensitivity in an exothermic packed-bed reactor means that temperature

The step in a chain reaction in which a radical reacts to give a product molecule and another radical is called

The correct sequence of steps in a heterogeneous catalytic reaction begins with

Chemisorption differs from physisorption in that it

The BET method is used to determine

In a Langmuir-Hinshelwood mechanism

If a reaction product appears in the denominator of a heterogeneous catalytic rate law, it indicates that the product

Which observation indicates that a catalytic reaction is controlled by external mass transfer?

For a catalyst pellet with a very large Thiele modulus, the effectiveness factor is approximately

When a reaction is strongly limited by internal pore diffusion, the apparent activation energy is approximately

Loss of catalyst activity by the growth of metal crystallites at high temperature is called

In a pulse tracer experiment, the normalised concentration response directly gives

The variance of the residence time distribution for an ideal plug flow reactor is

In the tanks-in-series model, the number of equivalent tanks is calculated as

The residence time distribution alone is sufficient to predict conversion for

Which of the following is a prokaryotic organism?

Sucrose on hydrolysis yields

Starch and cellulose are both polymers of glucose but differ in

The structural component of all cell membranes, being amphipathic, is

Amino acids are joined together in a protein by

The secondary structure of a protein, such as the alpha helix, is stabilised mainly by

Which base is present in RNA but not in DNA?

In DNA, guanine pairs with cytosine through

The net ATP yield from the complete aerobic oxidation of one molecule of glucose is approximately

The theoretical yield of ethanol from glucose by fermentation is about

The Pasteur effect refers to

The lac operon of E. coli is an example of

Immobilisation of an enzyme on a solid support typically results in

Which of the following is a renewable but conventional source of energy?

Hydrogen is best described as

Which rank of coal has the highest carbon content and calorific value?

The proximate analysis of a coal reports

The gross calorific value of a fuel is always greater than its net calorific value because

The mass of oxygen theoretically required to burn 1 kg of carbon completely to carbon dioxide is

In the Orsat apparatus, the gases are absorbed in the order

Supplying a large excess of air to a furnace

For a high-head, low-flow hydropower site, the most suitable turbine is

Gasification differs from combustion in that gasification

The chief constituent of biogas produced by anaerobic digestion is

A fuel cell is more efficient than a conventional thermal power plant principally because

In the electrolysis of water, the gases liberated at the cathode and anode respectively are

The negative sign in Fourier's law of heat conduction indicates that

The thermal resistance of a hollow cylinder of inner radius r1 and outer radius r2 is

In a composite wall, the largest temperature drop occurs across the layer with

Thermal diffusivity is defined as

The critical radius of insulation for a cylindrical pipe is given by

Adding insulation to a small-diameter electrical wire whose radius is below the critical radius will

For a plane wall, the critical thickness of insulation

Fin efficiency is defined as the ratio of the actual heat transferred by the fin to the heat that would be transferred if

Fins are most effective when added to a surface in contact with

The Biot number represents the ratio of

The lumped capacitance method for unsteady conduction may be applied when the Biot number is

In the lumped capacitance model, the temperature of a body approaches that of its surroundings

Most common insulating materials owe their low thermal conductivity to

The convective heat transfer coefficient h is

The Nusselt number represents the ratio of

The Prandtl number of a fluid is

For fully developed laminar flow in a tube with constant wall temperature, the Nusselt number is

In the Dittus-Boelter equation, the exponent on the Prandtl number is

According to the Dittus-Boelter equation, doubling the velocity in a tube increases the heat transfer coefficient by a factor of about

In natural convection, the Reynolds number is replaced by the

For turbulent natural convection, where the Nusselt number varies as the Rayleigh number to the power one third, the heat transfer coefficient is

The critical heat flux in pool boiling corresponds to

In the transition boiling regime, as the excess temperature is increased the heat flux

Dropwise condensation gives a higher heat transfer coefficient than filmwise condensation because

The presence of a small amount of non-condensable gas in a condenser

Condenser tubes are usually arranged horizontally rather than vertically because

According to the Stefan-Boltzmann law, the emissive power of a black body is proportional to

The value of the Stefan-Boltzmann constant is approximately

Wien's displacement law states that as the temperature of a body increases, the wavelength of maximum emission

Kirchhoff's law of radiation states that at thermal equilibrium

For an opaque surface, the sum of absorptivity and reflectivity is

A grey body is one whose

Which of the following surfaces has the lowest emissivity?

The view factor between two surfaces depends on

For a flat or convex surface, the view factor with respect to itself, F11, is

For a small grey body of emissivity e1 completely enclosed by a much larger surface, the net radiant exchange depends on

For radiation exchange between two large parallel grey plates, the denominator of the exchange expression is

Inserting a single radiation shield of the same emissivity between two large parallel plates reduces the radiant heat transfer to