Agriculture And Industry

Question 1

Things that help food production ( plant growth)

Answer 1

Fertilizers add nutrients for plant growth (NO3^-, PO4^3-, K+)
Mature adds organic matter for plant growth and soil improvement
Like or chalk added to the soil will alter pH of soil
Pesticides (insecticides, fungicides and weed killers) increase crop yields. Need to be biodegradable so don’t accumulate in food
chains
GM crops can be developed to give crops with desirable properties

Question 2

Recycling of materials- principles of green chemistry

Answer 2

Minimize waste
Reduce energy consumption
Reduce feedstock consumption

Question 3

Kc - what does it mean

Equation for it

Answer 3

Kc= conc of products / conc of reactants
Number of moles = powers
Equilibrium constant at a specified temperature

Question 4

Kc is a measure of…

Kc = small? Large?

Answer 4

How far a reaction proceeds
Small- mixture is largely reactants
Large - mixture Is largely products

Question 5

What affect Kc?

Answer 5

Change in temperature.

Question 6

Exothermic -

Temp affect on Kc

Answer 6

Temp increases = Kc decreases

Temp decreases = Kc increases

Question 7

Endothermic reaction temp affect of Kc

Answer 7

Temp increases Kc increases

temp decreases Kc decreases

Question 8

Name giant lattice examples (3)

Answer 8

Ionic, covalent network and metallic

Question 9

Ionic lattices - what substances have this structure?
Examples
What type of particles does it contain?
How are the particles bonded?

Answer 9

Compounds of metals and non-metals
Eg- sodium chloride, calcium oxide
Type of particles - ions
How’re they bonded? Strong ionic bonds: attraction between oppositely charged ions

Question 10

Covalent network 
what substances have this structure?
Examples 
What type of particles does it contain? 
How are the particles bonded?

Answer 10

What substances have this structure- Some elements in group four and some of their compounds
Eg diamond, graphite, silica
Type of particles does it contain? Atoms
What bonds are present? Strong covalent bonds

Question 11

Metallic 
what substances have this structure?
Examples 
What type of particles does it contain? 
How are the particles bonded?

Answer 11

Substances - metals
Eg sodium, copper, iron
Type of particles - positive ions surrounded by delocalised electrons
What bonds present- strong metallic bonds, attraction of atoms’ nuclei for delocalised electrons

Question 12

Name both types of covalent molecular (2)

Answer 12

Simple molecular and macromolecular

Question 13

Simple molecular - what substances have this structure?
Examples
What type of particles does it contain?
How are the particles bonded?

Answer 13

Substances - some non metal elements and some non metal/ non metal compounds
Eg carbon dioxide, chlorine and water
Type of particles - small molecules
How’re the particles bonded weak intermolecular bonds between molecules, strong covalent bonds between the atoms within each molecule

Question 14

Macromolecular-
what substances have this structure?
Examples 
What type of particles does it contain? 
How are the particles bonded?

Answer 14

Substances - polymers
Example - DNA, nylon, polyethene
Type of particles does it contain- long-chain molecules
How’re they bonded?
Weak intermolecular bonds, strong covalent infra bonds between atoms in the molecule

Question 15

Ionic - typical properties

Answer 15

High mp and bp
Hard but brittle
Conduct electricity when molten to dissolved in water, electrolytes
Solubility in water - often soluble
Solubility in non polar solvents - generally insoluble

Question 16

Covalent network typical properties

Answer 16

Very high mp and bp
Very hard if 3D
Do not normally conduct (except graphite)
Solubility in water - insoluble
Solubility in non polar solvents - insoluble

Question 17

Metallic typical properties

Answer 17

Generally high melting point and bp (except Mercury)
Hard but malleable
Conduct electricity when solid or liquid
Insoluble in water (but some react)
Solubility in non polar solvents - insoluble

Question 18

Simple molecular typical properties

Answer 18

Mp and bp low 
Soft
Do not conduct electricity 
Usually in soluble unless molecules contain groups that can hydrogen bond 
Usually soluble in non polar solvents

Question 19

Macromolecular typical properties

Answer 19

Bp and mp - moderate often decompose on heating
Vary in hardness, many are soft but often flexible
Do not normally conduct electricity
Solubility in h2o usually insoluble
Sometimes soluble in non polar solvents

Question 20

Haber process equation and conditions

Answer 20

N2(g) +3H2 (g) (eq) 2NH3 (g) delta H = -92kJmol^-1

Iron catalyst , 450 degrees & 200atm

Question 21

Affect of increasing temp and pressure on haber process

Answer 21

Increasing temp - shifts eq to left as forward reaction exothermic, increases rate eq is achieved

Increasing pressure increases both yield and rate, but is expensive and running costs are high.
Using catalyst speeds up the rate at which equilibrium is achieved.

Question 22

Nitrogen gas consists of _____ molecules which are very _____ because of the ____ activation energy needed to start breaking bonds

Answer 22

Diatomic molecules
Unreactive
High

Question 23

Denitrifying bacteria in soil

Answer 23

Nitrogen gas N2 oxi state 0

Dinitrogen (I) oxide (nitrous oxide) N2O oxi state +1

Question 24

Nitrifying bacteria in soil

Answer 24

Nitrate (V) ion NO3- (aq) oxi state +5

Nitrate (III) ion NO2- (aq) oxi state +3

Question 25

Root nodules in legumes, Bacteria and microorganisms in soil

Answer 25

Ammonium ion NH4+ (aq) oxi state -3

Question 26

Car engines, thunderstorms, denitrifying bacteria in soil

Answer 26

Nitrogen (II) oxide (nitrogen monoxide) +2 NO(g)

Question 27

Oxidation of NO in atmosphere

Answer 27

Nitrogen (IV) oxide nitrogen dioxide +4

NO2 (g)

Question 28

N2O
NO
NO2 colour of gases

Answer 28

N2O and NO ARE COLOURLESS

NO2 is brown gas at rt