Agriculture + Industry
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- Created by: Kate Prescott
- Created on: 06-05-13 19:12
What do N20, NO, and NO2 look like at room temperature?
N2O = colourless gas, NO = colourless gas, NO2 = brown gas
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What is the formula of the Nitrate (V) ion
NO3-
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What is the formula of the Nitrate (III) ion?
NO2-
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What is the formula of the ammonium ion?
NH4+
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Which chemical species are produced by denitrifying bacteria in the soil?
N2, N2O, NO gasses
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Which chemical species are produced by nitrifying bacteria in the soil?
NO3-, NO2- aqueous ions
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How is nitrogen (IV) oxide produced?
NO2 is produced by the oxidation of NO in the atmosphere
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How are ammonium ions produced?
Nitrogen fixing bacterial in root nodules in legumes and bacterial and microorganisms in the soil
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What is the definition of nitrogen fixation?
The conversion of nitrogen gas into soluble nitrogen compounds
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What is the equation for the bacterial nitrogen fixation of N2(g) into NH4+?
N2 + 8H+ + 6e- = 2NH4+
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What is the equation for the lightening fixation of nitrogen and oxygen gas to form nitrogen (II) oxide?
N2 + O2 = 2NO
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What are the equations for the bacterial nitrification of ammonium ions into nitrate (III) ions and then into nitrate (V) ions?
1. NH4+ + 1.5O2 = NO2- + 2H+ + H2O 2. NO2- + 0.5O2 = NO3-
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How are inorganic nutrients naturally brought into the soil?
Break down of minerals in soil/ rock by physical weathering
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How are organic nutrients naturally brought into the soil?
The decomposition of plants/ animals/ excrement and mineralisation (conversion of organic material into ions)
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How are nutrients lost from the soil?
Leaching by rainwater, uptake by plants (followed by their removal by humans and thus the nutrients are not recycled into the soil via humus), loss of ammonium gas in alkaline soil, denitrification by bacteria in anaerobic soils
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How can nitrogen be added to soil in organic farming?
Ploughing certain crops back into the soil, applying composts and farmyard manure, applying permitted mineral fertilisers
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What is the benefit of crop rotation?
Different minerals are taken from the soil by different plants, so there are always sufficient nutrients for each crop as the land has time to recover. Also, crops can be staggered throughout the year and there isn't time for pests to build up
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What are the problems with nitrogen containing fertilisers?
Nitrate ions are more easily leached out of the soil, making their way into rivers and causing eutrophication as well as causing health concerns over the amount of nitrate in drinking water
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How can acidic clay soils be neutralised?
The addition of large amounts of a basic carbonate (e.g. CaCO3) or base (e.g. Ca(OH2)) as clay soils are acidic buffers
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What is the equation for the equilibrium constant for the equation aA + bB = cC + dD?
Kc = [C]^c[D]^d / [A]^a[B]^b
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Where does the position of equilibrium lie if Kc < 1?
On the left
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Where does the position of equilibrium lie if Kc > 1?
On the right
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What factor affects the value of the equilibrium constant for a particular reaction?
Temperature
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What is the equation for the percentage yield of a reaction?
% yield = actual yield / predicted yield *100
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What is the equation for the atom economy of a reaction?
Mr of desired product / Mr or reactants *100
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What are the principles of green chemistry?
Minimise waste (high atom economy + percentage yield or recycling unreacted reactants), minimise the use of environmentally hazardous products such as heavy metal catalysts, maximise energy efficiency
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How does using an enzyme agree with the principles of green chemistry?
It lowers the activation enthalpy so a lower temperature can be used, reduced the number of reaction steps and so increases the atom economy, isn't environmentally hazardous to dispose of, is reusable, and is specific to a substrate (higher % yield)
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What is the difference between a co-product and a by-product?
A co-product is produced as part of the desired reaction, whereas a by-product is produced as part of an undesired reaction taking place in the same reaction vessel
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How can farmers save money and protect the environment when growing crops
Using a minimum amount of fertiliser and planting winter crops - there continue the consumption of nitrate (V) and so reduce the leaching of nitrates into the water system
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What is the name given to the pesticide which kills weeds?
Herbicide
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What is the name given to the pesticide which kills insects?
Insecticide
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What is the name given to the pesticide which kills fungi?
Fungicide
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What are the main causes of low crop yield?
Insects (eat crops); weeds (complete with crops for nutrients, space + sunlight); moulds (rot plants + seeds); disease (kills plants, often carried by another organism)
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How can pests be controlled in organic farming?
Crop rotation (pests don't have enough time to colonise); physical barriers (e.g. netting); encouraging predators (e.g. ladybirds); weeding; limited use of permitted pesticides; companion planting (e.g. garlic repels aphids)
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What is a total herbicide?
A herbicide which destroys all green plant species in an area by targeting leaves
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What is a selective herbicide?
A herbicide which targets particular plant features common to weeds only
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What are the problems with total herbicides?
They also kill the crop, so cannot be sprayed on crop during growth; they can be displaced from the soil by water and damage the growing crop
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What is a systematic fungicide?
A fungicide which spreads throughout the whole of the plant, including new growth
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What are the essential properties of new pesticides?
Doesn't tend to persist in the environment/ enter water supplies; specific; kills at low doeses
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What are the problems associated with non-specific pesticides?
May kill predators of the pest; kill more organisms if spread into the environment; kill desirable organisms such as bees
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What are the problems associated with persistent pesticides?
They take many years to degrade into harmless substances so are more dangerous if released into water supplies; continue to kill organisms after the crop has been harvested; more likely to bioaccumulate and kill top predators
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How are carbamates synthesised via addition?
R-NH-CO-NH-R + R-O-CO-O-R = 2R-NH-CO-O-R; silica gel catalyst, 150 C; 8 hours
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What is the order of electronic subshells up to Z=36?
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6
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Giant covalent lattice structures' melting points are...?
Very high
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Giant covalent lattice structures' solubilities in water are...?
Very low (insoluble)
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Giant covalent lattice structures' electrical conductivities are...?
Very low (do not conduct - except graphite)
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Giant ionic lattice structures' solubilities are...?
Very high (soluble)
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Giant ionic lattice structures' melting point are...?
Very high
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Giant ionic lattice structures' electrical conductivities are...?
Very low when solid, fairly high when molten or aqueous
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Metallic lattices melting points are...?
Very high
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Metallic lattices solubilites in water are...?
Very low (insoluble)
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Metallic lattices electrical conductivity are...?
Very high
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Simple molecular molecules' melting points are...?
Very low
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Simple molecular structures' solubilities in water are...?
Variable
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Simple molecular structures' electrical conductivities are...?
Very low (do not conduct)
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What is the shape and bond angle of a molecule with two regions of electron density around the central atom?
Linear,180
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What is the shape and bond angle of a molecule with three bonds to other atoms from the central atom?
Trigonal planar, 120
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What is the shape and bond angle of ammonia?
Pyramidal, 109
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What is the shape and bond angle of a molecule with five groups of electrons around the central atom?
Bipyramidal, 120 or 90
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What is the shape and bond angle of a complex with six ligands around the central ion?
Octahedral, 90
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Do lone pairs contribute to the shape of a molecule?
Yes
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Increasing the temperature increases the rate of a reaction because...?
The kinetic energy of the particles increases, so more colliding molecules have greater than the activation enthalpy for the reaction. Also, particles move around faster, increasing the frequency of successful collisions.
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Increasing the pressure increases the rate of a reaction between gaseous molecules because...?
Gas molecules are closer together, so travel less far between collisions, leading to a higher frequency of successful collisions
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Adding a catalyst increases the rate of a reaction because...?
Catalysts provide an alternative route for the reaction with a lower activation enthalpy. Therefore, more colliding molecules will have greater than the activation enthalpy required for the reaction, increasing the frequency of successful collisions
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In the Haber process, increasing the temperature moves the equilibrium position...?
To the left - in the endothermic direction, to counteract the increase in temperature
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In the Haber process, increasing the pressure moves the equilibrium position...?
To the right - to counteract the increase in pressure by moving to the side with least moles of gas
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In the Haber process, adding a catalyst moves the equilibrium position...?
Adding a catalyst has no effect on the equilibrium position as it increases the rate of the forwards and backwards reaction equally
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What is oxidation?
The increase in oxidation state or loss of electrons
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What is reduction?
The decrease in oxidation state or gain of electrons
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Other cards in this set
Card 2
Front
What is the formula of the Nitrate (V) ion
Back
NO3-
Card 3
Front
What is the formula of the Nitrate (III) ion?
Back
Card 4
Front
What is the formula of the ammonium ion?
Back
Card 5
Front
Which chemical species are produced by denitrifying bacteria in the soil?
Back
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