Which of the following is true about a chemical reaction that follows a second order kinetics?

a) …………… The reaction rate is dependent upon the temperature.

b) …………… The reaction rate is dependent upon the concentration of the reaction products.

c) …………… The conversion of a reactant after a given time is dependent upon its initial concentration.

 

Okay, let's analyze the three statements about a chemical reaction that follows second-order kinetics:

 

a) The reaction rate is dependent upon the temperature.

This statement is true. The rate of a second-order reaction is dependent on the temperature, as described by the Arrhenius equation, which relates the rate constant to the temperature.

 

b) The reaction rate is dependent upon the concentration of the reaction products.

This statement is false. In a second-order reaction, the rate is dependent on the concentration of the reactants, not the products.

 

c) The conversion of a reactant after a given time is dependent upon its initial concentration.

This statement is true. In a second-order reaction, the conversion of a reactant after a given time is directly proportional to its initial concentration.

 

Therefore, the statements that are true about a chemical reaction that follows second-order kinetics are:

a) The reaction rate is dependent upon the temperature.

c) The conversion of a reactant after a given time is dependent upon its initial concentration.

 

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Which of the following is true about a thermal effect of a reaction?

a) …………… The (overall) thermal effect of a reaction is dependent on a reaction rate. The faster the reaction proceeds the more heat it will generate or consume.

b) …………… The thermal effect of a reaction can by calculated if the heat of combustion of the reactants and the products is known.

c) …………… The amount of heat exchanged by a reaction with the exterior is independent upon the starting and the final temperature of the reaction mixture.

d) …………… In a complex reaction there can be multiple steps involving both exothermic and endothermic elementary reactions, but the thermal effect of each cannot by usually observed. What is observed instead is an overall thermal effect due to a large number of atoms/molecules reacting at the same time in each of these stages.

 

Let's go through the statements one by one:

 

a) The (overall) thermal effect of a reaction is dependent on a reaction rate. The faster the reaction proceeds the more heat it will generate or consume.

This statement is false. The thermal effect of a reaction is determined by the enthalpy change (ΔH) of the reaction, which is independent of the reaction rate.

 

b) The thermal effect of a reaction can by calculated if the heat of combustion of the reactants and the products is known.

This statement is true. The thermal effect of a reaction can be calculated using the heat of combustion of the reactants and products, as long as the reaction is a combustion reaction.

 

c) The amount of heat exchanged by a reaction with the exterior is independent upon the starting and the final temperature of the reaction mixture.

This statement is false. The amount of heat exchanged by a reaction with the exterior is dependent on the temperature difference between the reaction mixture and the surroundings, as described by the first law of thermodynamics.

 

d) In a complex reaction there can be multiple steps involving both exothermic and endothermic elementary reactions, but the thermal effect of each cannot by usually observed. What is observed instead is an overall thermal effect due to a large number of atoms/molecules reacting at the same time in each of these stages.

This statement is true. In a complex reaction, there can be multiple elementary steps, some of which may be exothermic and others endothermic. However, the overall thermal effect observed is the sum of these individual effects, as a large number of atoms/molecules are reacting simultaneously.

 

Therefore, the statements that are true about the thermal effect of a reaction are:

b) The thermal effect of a reaction can be calculated if the heat of combustion of the reactants and the products is known.

d) In a complex reaction there can be multiple steps involving both exothermic and endothermic elementary reactions, but the thermal effect of each cannot by usually observed. What is observed instead is an overall thermal effect due to a large number of atoms/molecules reacting at the same time in each of these stages.

 

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Which of the following is true about the estimation of process costs?

a) …………… The variable costs of a process can be roughly calculated based on the market prices of products which this process will produce.

b) …………… The capital investment costs can be estimated only after a complete and detailed project (PFD’s, equipment listings, automation and instrumentation, construction plans) is evaluated.

c) …………… The annual cost of labour can be estimated roughly as 0,1 × capital investment costs.

d) …………… For most of chemical feedstocks their price can be correlated to the price of primary raw materials from which they are ultimately produced (e.g. natural gas, coal, crude oil), or even better, from commodities which are used to produce these feedstocks more directly (like ethylene, benzene, calcium hydroxide, methanol, etc.). For example, the price of cyclohexanone will be better correlated to a commodity which is closer to it in the production chain: crude oil → benzene, propylene → cumene → phenol → cyclohexanone, if that’s the only route leading to this particular product (as a side note, in this example  it’s not).

e) …………… The geographical location of a plant can determine which chemical pathway is selected for the manufacturing of a particular product.

 

Let's go through the statements one by one:

 

a) The variable costs of a process can be roughly calculated based on the market prices of products which this process will produce.

This statement is false. The variable costs of a process are typically based on the costs of raw materials, utilities, and other variable inputs, not the market prices of the products.

 

b) The capital investment costs can be estimated only after a complete and detailed project (PFD's, equipment listings, automation and instrumentation, construction plans) is evaluated.

This statement is true. Accurate estimation of capital investment costs requires a detailed engineering design and evaluation of the process.

 

c) The annual cost of labour can be estimated roughly as 0,1 × capital investment costs.

This statement is false. The annual cost of labor is typically estimated based on the number of employees, their salaries, and other labor-related costs, not as a fraction of the capital investment.

 

d) For most of chemical feedstocks their price can be correlated to the price of primary raw materials from which they are ultimately produced (e.g. natural gas, coal, crude oil), or even better, from commodities which are used to produce these feedstocks more directly (like ethylene, benzene, calcium hydroxide, methanol, etc.). For example, the price of cyclohexanone will be better correlated to a commodity which is closer to it in the production chain: crude oil → benzene, propylene → cumene → phenol → cyclohexanone, if that's the only route leading to this particular product (as a side note, in this example  it's not).

This statement is true. The prices of chemical feedstocks are often correlated to the prices of their primary raw materials or closer commodities in the production chain.

 

e) The geographical location of a plant can determine which chemical pathway is selected for the manufacturing of a particular product.

This statement is true. The availability and cost of raw materials, utilities, and other factors can influence the selection of the most appropriate chemical pathway for a particular product based on the plant's geographical location.

 

Therefore, the statements that are true about the estimation of process costs are:

b) The capital investment costs can be estimated only after a complete and detailed project (PFD's, equipment listings, automation and instrumentation, construction plans) is evaluated.

d) For most of chemical feedstocks their price can be correlated to the price of primary raw materials from which they are ultimately produced (e.g. natural gas, coal, crude oil), or even better, from commodities which are used to produce these feedstocks more directly (like ethylene, benzene, calcium hydroxide, methanol, etc.). For example, the price of cyclohexanone will be better correlated to a commodity which is closer to it in the production chain: crude oil → benzene, propylene → cumene → phenol → cyclohexanone, if that's the only route leading to this particular product (as a side note, in this example  it's not).

e) The geographical location of a plant can determine which chemical pathway is selected for the manufacturing of a particular product.