Chemical Monitoring and Management Flashcards
What are the 4 conditions influencing the equilibrium position for the haber process reaction?
- Temperature: 400-450 degrees
- Concentration
- Pressure 250-300 atmospheres
- Volume
What are the haber process reaction conditions?
All conditions are compromised to produce most efficient yield
- Temperature: decrease temp as reaction is exothermic (increases yield)
*this slows down reaction, so compromise temperature: is 400-450 degrees
Catalyst: magnetite (Fe3O4) - Concentration
- Pressure
(As ammonia is formed volume of gas decreases), thus high pressure used. (However safety and cost issues)
Pressure: 250-300 atmospheres
-continual removal of ammonia
-recycling of reactants
-molar ratio 3:1 hydrogen to nitrogen
-hydrogen used may contain methane and carbon monoxide, damaging to the reaction &a must be monitored
In the haber process why is it critical to monitor the reaction vessel?
That conditions and process required to achieve yield are maintained
What is the history of the haber process?
L
What are the uses of AAS?
- used when concentrations are too low to titrate and gravimeteric analysis isn’t sensitive enough
Impacts:
-improved understanding of trace elements for our health. eg. Fe to produce haemoglobin
-to test soil fertility eg. Mg & Zn are critical to plant growth
How does AAS work?
- Special hollow cathode lamps shine the specific wavelength an atom absorbs into the vaporised metal sample being examined.
- The amount of light absorbed in the photomultiplier is proportional to the concentration of the metal in the flame.
- A calibration curve is used to get concentration values from absorbance values (generated through standard solutions {A=KC})
- AAS can’t be used unless what ion is present in the sample is known.
- Only cations can be tested for, & only one can be tested at a time
What are the principles of AAS?
- Selective absorbance of wavelengths by vapors
- Concentration is proportional to absorbance.
- when different metals vaporise in flame, they absorb light with specific frequencies
- an atom’s electrons have discrete energy levels
- When an atom absorbs energy, the e- enters a higher energy level in which it releases energy as it returns to its normal state
- this energy is given off as light that is split into its component lengths
How has AAS impacted on scientific understanding on the effects of trace elements?
- the importance & ideal concs of trace elements in the body could be determined by testing sick people & comparing results
- AAS is the only testing that is SENSITIVE, ACCURATE & EFFICIENT enough to study trace elements due to their extremely low concentrations
What are the colours metals give off in flame tests?
Calcium -red Barium - apple (pale) green Potassium -violet Sodium -yellow Copper -greenblue
What do flame tests rely on?
Metals giving off different coloured light in flames
(e- emit different wave lengths, hence different colours)
Different metals give off different colours due to the varying gaps between e- energy shelves, allowing flame tests to distinguish between them.
information about a practsing scientist:
Dr. Simpson at Monash uni is a medical chemist working in medicine. he is researching next generation antibiotics to combat resistant bacteria.
Branch of chemistry: analytical & organic
What is the chemical principle used by Dr. Simpson?
Thin layer Chromatography.
- Used by medical chemists to identify components of mixtures.
- A TLC plate with a tiny amount of substance is placed into a TLC chamber.
- It is then separated by solved vapour & separated substance then travels along the plate at different rates.
- The sample is then analysed under UV light.
What are the layers of the atmosphere from the earth going up?
Troposphere
Stratosphere
Mesosphere
Thermosphere
Changes in temperature mark the barrier for each layer
Troposphere
75% of gas in the atmosphere
-N2, O2, CO2and water vapour
Stratosphere
24% of atmosphere
Ozone layer (contains highest concentration of ozone) ➡️absorbs light from sun
