Chemistry Module 5 Flashcards
What is Cycads
Cycads are a source of nutrition containing neurotoxins
What is Cycasin
Cycasin is a soluble compound in water that can be removed by leaching in running water making this nutrition source available for human consumption.
Benefits of PROCESSING the cycad pulp for cycasin
Continually adding fresh water and diluting the cycasin allows the equilibrium positon to move towards the aqueous/product side continually. By leaching in running water, there is no need to replace, or drain the water every time an equilibrium is established.
NH3 has a higher boiling point than N2 and H2. The NH3 produced is condensed to a liquid at a temperature where N2 and H2 remain gases to allow efficient extraction of products from the reaction mixture.
The process is at a ‘steady state’ as the reactor and the condenser gases are well mixed so that the concentration exiting these regions is the same as those present in these regions.
Temperature in Haber Process
A ‘compromise’ is reached between conditions favouring a fast reaction rate and conditions favouring a yield.
Temp of 400 - 500 degree celsius - this allows a fast reaction rate and also a reasonable yield.
Pressure of 250 atm
Pressures that are too high lead to a variety of concerns including safety issues and high costs.
Magnetite (iron) catalyst
allows a lower reaction temperature and faster rate of reaction.
Explain Temp & Pressure used in industry to produce ammonia (NH3) are a ‘compromise’ between reaction rate, yield, cost and safety
A compromise is reached between conditions favouring a fast reaction rate and conditions favouring a high yield.
Temp of 400 - 500 degrees allows a fast reaction rate and also a reasonable yield.
Pressure at 250 atm is too high leading to a variety of concerns such as safety issues and high costs.
Magnetite catalysts allow a lower reaction temperature and faster rate of reaction.
Pressure in Haber Process
The ratio of the molle is 2:1, hence the forward reaction is favoured.
The equation for combustion reaction/Is it dynamic or static? Why?
Combustion reaction is non equilibrum
CH3CH2OH + 3O2 -> 2CO2 + 3H2O
G is largely negative therefore, a spontaneous reaction that is a non-equilibrium system.
The two non-equilibrium systems
- Photosynthesis
- Combustion
The equation for photosynthesis/Is it dynamic or static? Why?
Photosynthesis is irreversible
6CO2 + 6H2O -> 6O2 + C6H12O6
The G is largely positive and therefore non-spontaneous and cannot be equilibrium.
Sodium chloride consists of sodium and chloride (Na + Cl)
Water is polar (has positive and negative charge), thus water can dissolve salt allowing the positive particle to attract to the negative chloride ions and negative part of water molecules attracting to the positive sodium ions.
The sodium chloride dissociates because the solid ionic crystals are 1:1 ratio and can be broken up tonions when disso,ved in water.
D
The molecules of a strong acid will dissociate into hydrogen ions and anions when dissolved in water, thus no interactions are left. (acid Y)
(acid x) none or ony some of the weak acid wil dissociate, forming an equiibrium between the intact molecules and its ions.
C
A saturated barium carbonate soution has solid and aqueous solution in dynamic equiibrium. This means that forward reacton is still occuring even though there is no microscopic change in the process. The barium carbonate will dissolve in solution and there will still be radioactive particles present in both solid residue and the filltrate solution.
A
Look at the formula sheet (the largest)
B
A
The Keq pf the equilibrium is small (K<1), thus the concentration of the reactants are greater than the products. This favous the reverse reaction where F- is accepting proton than CF3COOH. Therefore F- is a strong base and CFCOOH a stronger acid.
A
HCO3 is an anthiprotic. As the pH is greater than 7, it is acting as a base, accpeting proton from H2O (water).
HCO3 + H2O = H2CO3 + OH-
B
0 < Ksp < 1 The reactant is slightly favoured.
B
D
D
According to the Le Chatelier’s principle increasing in pressure will shift the equilibrium position to the side with fewer gas moles. However, in this reaction the principle does not apply since there are no gases involved in the reaction. Increase in pressure will not affect the chemical reaction.
(a) The reaction is exothermic reaction (H>0), thus the activation energy must be less in the forward reaction than the reverse reaction. The Ea forward reaction (forming N2O4) is less than the Ea revese reaction (forming NO2). (Draw diagram)
(b) According to Le Chatelier’s principle, adding a temperature will shfit the equilibrium position to favor the endothermic direction. Therefore, increasing the temperature in this reaction will favor the left hand side (formation of NO2) as this minimise the increase in heat content. *Favoring the reverse reaction/endothermic.
(a) According to Le Chatelier’s principle, increasing the volume (decrease in pressure) will drive the reaction to the side with greater moles of gas. This reaction has lesser gas moles on the right hand side than the left , thus when decreasing the volume (increasing pressure) will shift the position to the right.
(b) Adding a catalyst to the equilibrium mixture will have no visible effect on the reaction reaction. This is because a catalyst will speed up the rate of both forward and the reverse reaction
(a) Two minutes
(b) The decomposition of COCl2 is endothermic.
(Le Chatelier’s principle)
Increasing temp will favor the product side where the heat is been absorbed, thus increasing the concentration of CO2 and Cl2 and decreasing COCl2.
C
C
A
D
A
H2CO3 is carbonic acid. By reacting it with NaOH (this reaction is unidirectional, not equilibrium), there is more ‘room’ to dissolve more CO2 gas, shifting the equilibrium to the right thus reducing the CO2 gas and pressure.
H2CO3 + 2NaOH -> Na2CO3 + 2H2O.
- To form NO product, the collisions between N2 and O2 must collide with right orientation and with enough energy.
- The activatio energy for the forward reaction is greater than the reverse, it is an endothermic.
- Increasing the temperature will shift the equilibrium position to the left (favour the right) and produce more NO.
- K = (NO)2/(N2)x(O2)
N2 + O2 = 2NO
C
C
C
