chemistry in society Flashcards
(19 cards)
What factors influence process design?
Factors include:
* availability, sustainability and cost of feedstock(s)
* opportunities for recycling
* energy requirements
* marketability of by-products
* product yield
Consideration of these factors is essential for efficient and sustainable process design.
What are the environmental considerations in process design?
Environmental considerations include:
* minimising waste
* avoiding the use or production of toxic substances
* designing products which will biodegrade if appropriate
These considerations aim to reduce the environmental impact of chemical processes.
What is the molar volume of a gas?
The molar volume is the same for all gases at the same temperature and pressure
This property allows for calculations involving the volume of gases based on the number of moles.
How can quantities of reactants and products be determined?
Using a balanced equation and:
* gram formula masses (GFM) and mass
* moles
* concentrations and volumes of solutions
* masses of solutes
* molar volumes and volumes for gaseous reactions
These methods provide a systematic approach to quantifying chemical species.
What is the concentration of a solution expressed in?
The concentration of a solution can be expressed in mol l-1
This unit indicates the number of moles of solute per liter of solution.
What formula is used to calculate percentage yield?
Percentage yield = actual yield / theoretical yield x 100
This formula helps assess the efficiency of a chemical reaction.
What is the difference between actual yield and theoretical yield?
The ‘actual yield’ is the quantity of the desired product formed under prevailing conditions, while the ‘theoretical yield’ is the quantity that would be obtained assuming full conversion of the limiting reagent
Understanding this difference is crucial for evaluating reaction outcomes.
How is atom economy calculated?
Atom economy = mass of desired product / total mass of reactants x 100
This calculation helps evaluate the efficiency of a chemical reaction in terms of resource utilization.
What can affect the atom economy of a reaction?
Reactions with a high percentage yield may have a low atom economy if large quantities of unwanted by-products are formed
Balancing yield and atom economy is important for sustainable chemistry.
What is dynamic equilibrium in reversible reactions?
In a closed system, reversible reactions attain a state of dynamic equilibrium when the rates of forward and reverse reactions are equal
This state is crucial for understanding chemical reaction behavior.
What factors can alter the position of equilibrium?
Factors include:
* changes in concentration
* changes in pressure
* changes in temperature
These factors influence the yield of products in reversible reactions.
What is the formula for calculating enthalpy change?
Eh = cm∆T
Here, c is specific heat capacity, m is mass, and ∆T is the temperature change.
What does Hess’s law state?
Hess’s law states that the enthalpy change for a chemical reaction is independent of the route taken
This principle allows for the calculation of enthalpy changes in complex reactions.
What is an oxidising agent?
An oxidising agent is a substance which accepts electrons
Understanding oxidising agents is essential for redox reactions.
What is a reducing agent?
A reducing agent is a substance which donates electrons
Recognizing reducing agents is important for predicting reaction outcomes.
What is the electrochemical series?
The electrochemical series is a series of reduction reactions that indicates the effectiveness of oxidising and reducing agents
This series is useful for selecting appropriate agents in chemical reactions.
What is the role of indicators in titrations?
An indicator is a substance which changes colour at the end-point of a titration
Indicators help visually determine the completion of a reaction.
What is volumetric analysis?
Volumetric analysis involves using a solution of accurately known concentration in a quantitative reaction to determine the concentration of another substance
This technique is widely used in analytical chemistry.
In chromatography, what is exploited to separate components of a mixture?
Differences in the polarity and/or size of molecules are exploited to separate components
This method is fundamental in analytical chemistry for mixture analysis.
