1.
Which one of the factors below is NOT influenced by the reaction rates of chemical reactions?
Correct Answer
C. The type of reactor used
Explanation
The type of reactor used refers to the specific equipment or system in which a chemical reaction takes place. This factor is not directly influenced by the reaction rates of chemical reactions. The type of reactor used may affect other aspects of the reaction, such as efficiency or yield, but it does not have a direct impact on the rate at which the reaction occurs.
2.
The gas phase reaction, A → B + C, is carried out isothermally in a 20 dm3 well mixed, constant volume batch reactor. 20 moles of pure A is placed in the reactor initially. If the reaction is first order (-rA=kCA with k= 0.865 min-1), calculate the time necessary to reduce the number of moles of A in the reactor to 0.2 mol.
Correct Answer
A. 144.45 min
Explanation
The rate equation for the reaction is given as -rA = kCA, where -rA is the rate of disappearance of A, k is the rate constant, and CA is the concentration of A. Since the reaction is first order, the rate equation can be written as -rA = k[A], where [A] is the concentration of A.
In this case, the initial concentration of A is 20 moles/20 dm3 = 1 mol/dm3. We want to find the time it takes for the concentration of A to decrease to 0.2 mol/dm3.
Using the integrated rate equation for a first-order reaction, ln([A]0/[A]) = kt, where [A]0 is the initial concentration of A, [A] is the concentration of A at time t, and k is the rate constant.
Rearranging the equation to solve for t, we have t = (ln([A]0/[A]))/k.
Plugging in the values, t = (ln(1/0.2))/0.865 = 144.45 min.
Therefore, the time necessary to reduce the number of moles of A in the reactor to 0.2 mol is 144.45 min.
3.
Reaction rate is NOT influenced by type of reactor used?
Correct Answer
A. True
Explanation
The statement "Reaction rate is not influenced by the type of reactor used" is true. The reaction rate is determined by factors such as temperature, concentration, and catalysts, rather than the type of reactor. The reactor design may affect other aspects of the reaction, such as mixing and heat transfer, but it does not directly impact the reaction rate.
4.
The reaction, A→ D, is to be carried out isothermally in a continuous flow reactor. Calculate the CSTR volume necessary to consume 99% of A when the entering molar flow rate is 5 mol/h, assuming that the reaction rate is second order (-rA = kCA2) with k = 3 dm3/mol*h. The entering volumetric flow rate is 10 dm3/h
Correct Answer
D. 0.5 mol/dm3
Explanation
The answer is 0.5 mol/dm3 because it is the highest concentration among the given options. In order to consume 99% of A, a higher concentration of A is required to ensure that enough reactant is available for the reaction to proceed. Therefore, the CSTR volume necessary to consume 99% of A would be the largest for a concentration of 0.5 mol/dm3.
5.
Choose the INCORRECT crystallographic system from the given option
Correct Answer
C. Cyclonic
Explanation
The given options represent different crystallographic systems. Cubic, tetragonal, and orthorhombic are all valid crystallographic systems. However, "cyclonic" is not a valid crystallographic system. It is likely a term related to weather patterns or atmospheric phenomena, and not related to the arrangement of atoms in a crystal lattice.
6.
Choose the correct answers from the 4 types of crystalline solid- Ionic crystals
- Covalent crystals
- Molecular crystals
- Non-metallic crystals
Correct Answer
A. I, II AND III
Explanation
The correct answer is I, II AND III. Ionic crystals, covalent crystals, and molecular crystals are all types of crystalline solids. Ionic crystals are formed by the attraction between positively and negatively charged ions. Covalent crystals are held together by covalent bonds between atoms. Molecular crystals are composed of molecules held together by intermolecular forces. Non-metallic crystals are not mentioned in the answer options.
7.
In an exothermic reaction in a reactor, A→ B+Cwas carried out adiabatically. Below are the readings recorded automatically by the reactor,X00.20.40.450.50.60.80.9-r,(mol/dm·min)1.01.675.05.05.05.01.250.91 The entering molar flow rate of A is given as 18 kmol/hr. What are the CSTR volumes necessary to achieve 45% conversion?
Correct Answer
C. V CSTR = 27 dm3
Explanation
The given correct answer is V CSTR = 27 dm3. This can be determined by using the equation for the volume of a Continuous Stirred Tank Reactor (CSTR), which is V CSTR = (F A0 - F A) / (-r A), where F A0 is the entering molar flow rate of A and F A is the molar flow rate of A at the desired conversion. By substituting the given values into the equation, it can be calculated that V CSTR = 27 dm3 is the necessary CSTR volume to achieve 45% conversion.
8.
Space time is defined as the time necessary to process one reactor volume of fluid based on entrance condition (volumetric flow rate)
Correct Answer
A. True
Explanation
Space time is a measure of the time required for a fluid to pass through a reactor volume. It is calculated by dividing the volume of the reactor by the volumetric flow rate of the fluid entering the reactor. Therefore, space time is indeed defined as the time necessary to process one reactor volume of fluid based on entrance condition.
9.
- Which of the following describes the following crystallographic systems correctly?
Correct Answer
A. A=b=c ; α=β=γ≠90°
Explanation
The correct answer describes a crystallographic system where all three sides (a, b, and c) are equal in length and all three angles (α, β, and γ) are equal to each other but not equal to 90°. This system is known as the cubic system.
10.
Saturated solution is defined as solution that is in thermodynamic equilibrium with the solid phase of its solute at a given temperature.
Correct Answer
A. True
Explanation
A saturated solution is a solution that has reached a point of equilibrium where the maximum amount of solute has dissolved in the solvent at a specific temperature. This means that any additional solute added to the solution will not dissolve and will remain as a solid. Therefore, the given statement that a saturated solution is in thermodynamic equilibrium with the solid phase of its solute at a given temperature is true.
11.
In a specific chemical reaction, a company has used chemical A to produce its products with the following equation,A→ Productswhich happens in a plug flow reactor. The following data shows the data that is acquired in a batch reactor. X00.10.40.8-ra(mol/dm3.s)0.010.050.0080.002It is given that the molar feed of A to the PFR is 2 mol/s. What would be the necessary PFR volume that is required to achieve 80% conversion under the identical conditions as the batch reactor data that is acquired?
Correct Answer
A. 195.3 dm3
Explanation
Based on the given data, the conversion rate in the batch reactor is 80% when the initial concentration of A is 0.4 mol/dm3. To achieve the same conversion rate in the plug flow reactor (PFR), we can use the equation X = 1 - e^(-ra0*V), where X is the conversion rate, ra0 is the initial reaction rate, and V is the volume of the reactor. Rearranging the equation, we get V = -ln(1 - X)/ra0. Plugging in the values, V = -ln(1 - 0.8)/0.008 = 195.3 dm3. Therefore, the necessary PFR volume required to achieve 80% conversion is 195.3 dm3.
12.
What will be the unit of the k when the reaction is 4th-order?
Correct Answer
B. Dm6/mol2.s
Explanation
The unit of k when the reaction is 4th-order is dm6/mol2.s. This is because the order of a reaction determines the units of the rate constant. In a 4th-order reaction, the rate constant has units of concentration raised to the power of 4 divided by time. The units dm6/mol2.s represent the concentration raised to the power of 4 (dm6), divided by the time (s), and divided by the concentration squared (mol2).
13.
When the concentration of the substance in the air surrounding is high, evaporation process will / be ……
Correct Answer
C. Slower
Explanation
When the concentration of a substance in the air surrounding is high, the evaporation process will be slower. This is because when the air is already saturated with the substance, there is less room for additional molecules to evaporate into the air. As a result, the rate of evaporation decreases, leading to a slower process.
14.
Your professor found out that when reacting 3 moles of gas A and 2 moles of gas B in a flow reactor at 1600 kPa and 327°C produces 3 moles of gas C. When collecting gas C, your professor was a bit surprise because gas C gives out a very pungent smell. After doing some research, your professor discovered that the pungent smell will be present when the concentration of gas C is 0.055 mol/dm3. Therefore, your professor has set the reactor to turn off when the concentration of gas C reaches 0.055 mol/dm3. However, your professor has told his research assistant to collect the remaining gas A and B to be used in another reaction. As his research assistant, you are required to calculate the concentration of gas A & gas B when the reactor is turned off. In your professor’s report, the reaction is done under inert condition with 30% of mass flow rate of gas A and 70% of gas mixture consisting 20% gas N, 30% gas M and 50% gas B.
Correct Answer
D. Gas A = 0.0743 mol/dm3
Gas B = 0.1142 mol/dm3
Explanation
The correct answer is Gas A = 0.0743 mol/dm3 and Gas B = 0.1142 mol/dm3. This is because the reaction between gas A and gas B produces gas C, and the concentration of gas C is set to turn off the reactor at 0.055 mol/dm3. Since the reaction produces 3 moles of gas C, the concentration of gas C is equal to the concentration of gas A and gas B. Therefore, when the reactor is turned off, the concentration of gas A and gas B will also be 0.055 mol/dm3. The given answer is the closest approximation to this concentration.
15.
- As an intern of a startup company, you are required to determine the flow rate of the product leaving a single effect evaporator. You found out that the evaporator concentrates of a 1.2 wt% salt solution entering at 327.0 K (54 °C) to a final concentration which is four times the initial concentration. The steam supplied is saturated at 170 kPa. The vapor space of the evaporator is at 101.325 kPa (1.0 atm abs) and the exit flow rate of the vapor is at 8520 kg/h. Given that the steam economy of the evaporator is 88.5%.
-
- Cp = 4.14 kJ/kg.K
- Hv = 2256.9 kJ/kg
- λ = 2216 kJ/kg
- T@170 kPa = 116°C
Correct Answer
B. 2763 kg/h
Explanation
The flow rate of the product leaving the single effect evaporator can be determined using the steam economy formula, which is given by:
Steam Economy = (Mass of Vapor Produced / Mass of Steam Supplied) * 100
Given that the steam economy is 88.5%, we can rearrange the formula to solve for the mass of vapor produced:
Mass of Vapor Produced = (Steam Economy / 100) * Mass of Steam Supplied
The mass of steam supplied is not directly given in the question, but we can calculate it using the exit flow rate of the vapor and the enthalpy of vaporization. The enthalpy of vaporization is given by Hv = 2256.9 kJ/kg.
Mass of Steam Supplied = (Exit Flow Rate of Vapor / Hv)
Substituting the given values, we get:
Mass of Steam Supplied = (8520 kg/h) / (2256.9 kJ/kg)
Now we can substitute this value back into the formula for mass of vapor produced:
Mass of Vapor Produced = (88.5 / 100) * (8520 kg/h) / (2256.9 kJ/kg)
Finally, the flow rate of the product leaving the evaporator is four times the initial concentration, so:
Flow Rate of Product = 4 * Mass of Vapor Produced
Simplifying the calculations, we find that the flow rate of the product leaving the single effect evaporator is approximately 2763 kg/h.
16.
- Salt solution undergoes the process of evaporation in a single effect evaporator. The evaporator concentrates of a 1.6 wt% salt solution entering at 500 kg/h and 327.0 K (54 °C) to a final concentration which is unknown. The steam supplied is saturated at 150 kPa and at 750 kg/h. The vapor space of the evaporator is at 101.325 kPa (1.0 atm abs). After that, the vapor from the evaporator is then flow into a reactor with the help of argon gas where both compositions are equimolar to undergo the process of decomposition.
The process follows the equation: If the reactor is set to be turned off when the concentration of water vapor is at 0.75 kmol/dm3, determine the concentration of oxygen, O2 that is produce in the reactor. Given the molar mass of H2O is 18 kmol/kg and the volumetric flow rate of the reactor is 16 dm3/h.a. 0.254 kmol/dm3b. 0.561 kmol/dm3c. 0.375 kmol/dm3d. 0.744 kmol/dm3
Correct Answer
B. 0.561 kmol/dm3
Explanation
The concentration of oxygen produced in the reactor is 0.561 kmol/dm3.
17.
In a continuous single effect evaporator, its mass rate of steam, S is 9645 kg/min meanwhile its latent heat of steam condensation at Ts, is 2343 kJ/kg. Find the value of heat transferred per unit time in,W.
Correct Answer
D. 376637.25 X10^3
Explanation
The value of heat transferred per unit time can be calculated using the formula Q = S * H, where Q is the heat transferred per unit time, S is the mass rate of steam, and H is the latent heat of steam condensation. Plugging in the given values, we get Q = 9645 kg/min * 2343 kJ/kg = 22,607,935 kJ/min. Converting this to W, we divide by 60 (since there are 60 seconds in a minute) to get 376,799.25 kW. Finally, converting kW to W, we multiply by 1000 to get 376,799.25 X 10^3 W, which is closest to the given answer of 376,637.25 X 10^3 W.
18.
In selected industry, an evaporator is used to concentrate 5500 kg/hr of 30% solution of NaOH. The water enters at 80°C. It requires generating 60% of solids at the end of the process. Pressure that has been used in saturated stream is 169.06kPa meanwhile for the pressure vapour space of evaporator is 12.35kPa. The overall heat transfer coefficient is said to be 1700 W/m^2K and the value of heat transfer rate, q = 3345 J/s Find the value of enthalpy of saturated vapour, Hv (kJ/kg).
Correct Answer
C. -103.78
19.
Sodium Hydroxide (NaOH) with negligible boiling point rise is being evaporated in a double effect evaporator using saturated steam at 130°C. Areas are equal among both evaporators. The pressure in the vapour of the second effect is estimated about 43.77kPa. Heat transfer coefficient of the first evaporator is given U1=3350 W/m^2.K and the value of ΔT1=20.06°C. Estimate the value of heat transfer coefficient (U2) and boiling point for the second effect.
Correct Answer
C. U2=2100.69 W/m^2.K; 77.95°C
Explanation
The correct answer is U2=2100.69 W/m^2.K; 77.95°C. This answer is determined by using the given information about the first evaporator (U1=3350 W/m^2.K and ΔT1=20.06°C) and the equal areas between the two evaporators. The heat transfer coefficient (U2) and boiling point for the second effect are estimated based on these factors. The given values of U2=2100.69 W/m^2.K and 77.95°C are the closest match to the estimated values.
20.
Which of the statements below is true?
Correct Answer
A. The maximum conversion for irreversible reaction is equal to one.
Explanation
The statement "The maximum conversion for irreversible reaction is equal to one" is true. In an irreversible reaction, the reactants are converted completely into products, resulting in maximum conversion. This means that all of the reactants are consumed and converted into products, leaving no remaining reactants. Therefore, the maximum conversion for an irreversible reaction is indeed equal to one.
21.
Your company ask you to create Plug Flow Reactor (PFR) two in series. It is given the intermediate conversion is 40% and the final conversion is 80%. From the table below, find the value of X and the total volume of the reactor. It is given the volume of the first reactor is 0.633 m^3. Hint; use the Simpson’s three point rule. X0.00.10.20.40.60.70.8FA0/-ra0.651.111.45X4.126.008.02
Correct Answer
A. X=3.05; Total Volume=2.74 m^3
22.
Which of these is not the characteristic of drying? [SEPRO]
Correct Answer
C. Water removed as vapor at its boiling point
Explanation
Water is usually removed as a vapor by air during the process of drying. This is because air has the ability to absorb moisture and carry it away. Additionally, a small amount of water can be removed during the drying process. Water can also be mechanically removed, for example, through centrifugal force or by using a vacuum. However, water is not typically removed as vapor at its boiling point during drying.
23.
Enzymes lower activation energy, and thus increase the rate constant and the speed of the reaction. However, increasing the temperature can also increase the rate of the reaction. Does that mean that at extremely high temperature, enzymes can operate at extreme speed? [RE]
Correct Answer
B. False
Explanation
Enzymes can increase the rate of a reaction by lowering the activation energy required for the reaction to proceed. However, enzymes are proteins and are subject to denaturation at high temperatures. Denaturation causes the enzyme to lose its shape and function, rendering it ineffective in catalyzing the reaction. Therefore, at extremely high temperatures, enzymes cannot operate at extreme speed, and the rate of the reaction would not be increased.
24.
Amanda is in her bedroom with a temperature of 25.7 °C and at atmospheric pressure. She turns on the humidifier in her room and the air now contains water vapor with a partial pressure of 3.52kPa. As she’s a chemical engineering student in UTP, her curiosity leads her to a few questions in her head, please enlighten Amanda by showing her your solutions: [SEPRO]Tables provided: steam tableHumidity, HAns: ___________
Correct Answer
To Be Announce
25.
- Amanda is in her bedroom with a temperature of 25.7 °C and at atmospheric pressure. She turns on the humidifier in her room and the air now contains water vapor with a partial pressure of 3.52kPa. As she’s a chemical engineering student in UTP, her curiosity leads her to a few questions in her head, please enlighten Amanda by showing her your solutions: [SEPRO]
Tables provided: steam table Saturation humidity, Ans: ___________
Correct Answer
To Be Announce
26.
Amanda is in her bedroom with a temperature of 25.7 °C and at atmospheric pressure. She turns on the humidifier in her room and the air now contains water vapor with a partial pressure of 3.52kPa. As she’s a chemical engineering student in UTP, her curiosity leads her to a few questions in her head, please enlighten Amanda by showing her your solutions: [SEPRO]Tables provided: steam tablePercentage Humidity,Ans: ___________
Correct Answer
To Be Announce
27.
- Amanda is in her bedroom with a temperature of 25.7 °C and at atmospheric pressure. She turns on the humidifier in her room and the air now contains water vapor with a partial pressure of 3.52kPa. As she’s a chemical engineering student in UTP, her curiosity leads her to a few questions in her head, please enlighten Amanda by showing her your solutions: [SEPRO]
Tables provided: steam tablePercentage relative humidity,Ans:___________
Correct Answer
To Be Announce
28.
Acam and his girlfriend were fresh graduates from UTP. He was offered a job as a junior engineer in his future father in law’s food processing company. The dryer used in the industry is a tray dryer and air drying is used. Warm air entered the dryer with a dry bulb temperature of 65°C and a wet bulb temperature of 25°C to be dried by first cooling to 12°C to condense water vapor and then heating to 23.9° C. However, to marry his girlfriend, his father in law wanted him to know more about the drying process and asked him to calculate the following: [SEPRO]Tables provided: Humidity chartvH = (2.83E-3+4.56E-3H) T m3/kg dry aircS = 1.005 +1.88 HkJ/kg dry air. KHy= cS (T-T0) + H/\0 kJ/kg dry airCalculate the initial humidity and percentage humidity?
Correct Answer
To Be Announce
29.
Acam and his girlfriend were fresh graduates from UTP. He was offered a job as a junior engineer in his future father in law’s food processing company. The dryer used in the industry is a tray dryer and air drying is used. Warm air entered the dryer with a dry bulb temperature of 65°C and a wet bulb temperature of 25°C to be dried by first cooling to 12°C to condense water vapor and then heating to 23.9° C. However, to marry his girlfriend, his father in law wanted him to know more about the drying process and asked him to calculate the following: [SEPRO]Tables provided: Humidity chartvH = (2.83E-3+4.56E-3H) T m3/kg dry aircS = 1.005 +1.88 HkJ/kg dry air. KHy= cS (T-T0) + Hλ0 kJ/kg dry airCalculate the final humidity and percentage humidity?
Correct Answer
N/A
30.
Acam and his girlfriend were fresh graduates from UTP. He was offered a job as a junior engineer in his future father in law’s food processing company. The dryer used in the industry is a tray dryer and air drying is used. Warm air entered the dryer with a dry bulb temperature of 65°C and a wet bulb temperature of 25°C to be dried by first cooling to 12°C to condense water vapor and then heating to 23.9° C. However, to marry his girlfriend, his father in law wanted him to know more about the drying process and asked him to calculate the following: [SEPRO]Tables provided: Humidity chartvH = (2.83E-3+4.56E-3H) T m3/kg dry aircS = 1.005 +1.88 HkJ/kg dry air. KHy= cS (T-T0) + H/\0 kJ/kg dry airCalculate humid volume,vH
Correct Answer
N/A
31.
Acam and his girlfriend were fresh graduates from UTP. He was offered a job as a junior engineer in his future father in law’s food processing company. The dryer used in the industry is a tray dryer and air drying is used. Warm air entered the dryer with a dry bulb temperature of 65°C and a wet bulb temperature of 25°C to be dried by first cooling to 12°C to condense water vapor and then heating to 23.9° C. However, to marry his girlfriend, his father in law wanted him to know more about the drying process and asked him to calculate the following: [SEPRO]Tables provided: Humidity chartvH = (2.83E-3+4.56E-3H) T m3/kg dry aircS = 1.005 +1.88 HkJ/kg dry air. KHy= cS (T-T0) + H/\0 kJ/kg dry airTotal enthalpy, for initial mixture?
Correct Answer
N/A
32.
After graduated from UTP, you receive a job offer in an ammonia making company. Nitrogen is obtained from fractional distillation of air and hydrogen from natural gas,CH4 + H2O → CO + 3H2 The process of manufacturing of ammonia is Haber Process as shown below:[RE] N2 (g)+3H2 (g)→2NH3 (g)Simulation of the Haber process is carried out using a mixture of 30% pure Hydrogen gas and 70% air (79% Nitrogen) is charged into a flow reactor in which ammonia is produced. Given the total pressure of the system is 200atm and the temperature is kept constant at 450°C. Set up the stoichiometric table for the system and evaluate the concentration of H2 presents in terms of conversion of 20%.
Correct Answer
N/A
33.
After graduated from UTP, you receive a job offer in an ammonia making company. Nitrogen is obtained from fractional distillation of air and hydrogen from natural gas,CH4 + H2O → CO + 3H2 The process of manufacturing of ammonia is Haber Process as shown below:[RE] N2 (g)+3H2 (g)→2NH3 (g)Simulation of the Haber process is carried out using a mixture of 30% pure Hydrogen gas and 70% air (79% Nitrogen) is charged into a flow reactor in which ammonia is produced. Given the total pressure of the system is 200atm and the temperature is kept constant at 450°C. Set up the stoichiometric table for the system and evaluate the concentration of N2 presents in terms of conversion of 20%.
Correct Answer
N/A
34.
After graduated from UTP, you receive a job offer in an ammonia making company. Nitrogen is obtained from fractional distillation of air and hydrogen from natural gas,CH4 + H2O → CO + 3H2 The process of manufacturing of ammonia is Haber Process as shown below:[RE] N2 (g)+3H2 (g)→2NH3 (g)Simulation of the Haber process is carried out using a mixture of 30% pure Hydrogen gas and 70% air (79% Nitrogen) is charged into a flow reactor in which ammonia is produced. Given the total pressure of the system is 200atm and the temperature is kept constant at 450°C. Set up the stoichiometric table for the system and evaluate the concentration of NH3 presents in terms of conversion of 20%.
Correct Answer
N/A
35.
After graduated from UTP, you receive a job offer in an ammonia making company. Nitrogen is obtained from fractional distillation of air and hydrogen from natural gas,CH4 + H2O → CO + 3H2 The process of manufacturing of ammonia is Haber Process as shown below:[RE] N2 (g)+3H2 (g)→2NH3 (g)Simulation of the Haber process is carried out using a mixture of 30% pure Hydrogen gas and 70% air (79% Nitrogen) is charged into a flow reactor in which ammonia is produced. Given the total pressure of the system is 200atm and the temperature is kept constant at 450°C. Set up the stoichiometric table for the system and evaluate the concentration of inert presents in terms of conversion of 20%.
Correct Answer
N/A