C11 Ammonia Flashcards
Ammonia
Alkaline gas made in the Haber process from nitrogen and hydrogen. NH3
Ammonium Salts
Ammonium nitrate, sulfate or chloride. Made by neutralizing ammonia with a particular acid. Very soluble and useful as a chemical fertilizer
Fertilizer
Compounds that contain vital elements required for healthy growth of plants. These mainly include the elements NPK (nitrogen, phosphorous, potassium)
Litmus paper
Used as a test for the alkaline nature of ammonia gas. Damp red litmus paper turns blue
Leaching
High solubility of chemical fertilizers in water means that they may be washed from the land into local streams and rivers, causing eutrophication.
How to reduce leaching
using less fertilizer and by not using before heavy rain
Eutrophication
Large amounts of fertilizer in streams and rivers causes excess growth of plants. When this dies and decays, the bacteria responsible for this uses up oxygen in the water and results in decreased dissolved oxygen content. Means marine life that requires high oxygen content cannot survive
Nitrogen fixation
The process by which nitrogen from the air can get into a soluble form that plants can take up in their roots. Due to the unreactive nature of nitrogen this can be achieved by nitrogen fixing bacteria and in the high temperatures created by storms. Nitrogen fixation can also be achieved in the Haber process.
Catalysts
Speed up rate of chemical reaction but are not used up in the process. Many transition metals make effective catalysts
Reversible reactions
reaction where the starting materials react to become products, but at the same time the products may decompose to become the starting materials. The rate of the forward and reverse reactions are equal and opposite. Often means that yield of product is low. Conditions such as temperature and pressure can be altered to give higher yields
Haber process definition
A reversible reaction where nitrogen and hydrogen react to give ammonia. Process is favored by high pressures and low temperatures with an iron catalyst
Uses of ammonia
production of nitric acid, fertilizer, pharmaceuticals, cleaning products and explosives
The Haber process
1) 3H2 + N2 (reversible) 2NH3
Hydrogen + nitrogen ammonia
2) gases compressed and delivered to reactor (iron catalyst used). cooled down, ammonia liquefied.
Where is the hydrogen needed in the haber process obtained
from the reaction of methane and steam- produces CO and H2
Where is the nitrogen needed in the haber process obtained
Hydrogen produced from methane and gas reacts with oxygen in the air, producing water, and leaving nitrogen behind (air is 78% nitrogen)
Conditions for haber process
1) High pressure- 200 atm
2) low temp- favors the forward exothermic reaction, but not that low; would take long to reach equilibrium
3) Iron catalyst- increases rate of equilibrium reached
Le Chatelier’s principle
a reaction in high pressure favors the side with less moles (in the case of the haber process, the forward reaction- producing ammonia)
Why can’t plants obtain nitrogen from the air
Nitrogen triple bond very strong, so it has to be fixed into soils and dissolved in water and absorbed by roots
The production of nitric acid from ammonia
1) 4NH3 + 5O2 -> 4NO+6H2O (with a platinum catalyst)
ammonia+ oxygen-> nitrogen monoxide +water
2) 2NO + O2 -> 2NO2
Nitrogen monoxide+ oxygen -> nitrogen dioxide
3) nitrogen dioxide and oxygen dissolve in water to form nitric acid
Composition of air
78% nitrogen
21% oxygen
1% other
Are ammonium salts soluble or insoluble in water?
It depends if there are mobile ions, such as K+, Na+,NH4+
Smell of ammonia gas
Pungent/ bad smell
Nitrogen fixing bacteria
they take nitrogen out of the air, and when they decompose/ decay, the nitrogen can be absorbed by plants
