CI.1 Flashcards
Redox reactions in the soil and the laboratory
Why is nitrogen so unreactive?
Nitrogen molecules contain two nitrogen atoms bonded together by a triple bond, which is very strong and requires a lot of energy to overcome.
What conditions are often required for molecular nitrogen to react?
High temperature and pressure, as well as a catalyst.
What is the equation for the haber process to make ammonia from nitrogen and hydrogen?
N2(g) + 3H2(g) ⇌ 2NH3(g)
What does ammonia have to be able to form a dative covalent bond to hydrogen ions to give ammonium ions?
A lone pair of electrons.
What are the three main nitrogen oxides?
- NO, nitrogen monoxide.
- NO2, nitrogen dioxide.
- N2O, dinitrogen monoxide
What is the appearance of nitrogen monoxide?
Colorless gas.
What is the appearance of nitrogen dioxide?
Brown gas.
What is the appearance of dinitrogen monoxide?
Colorless gas.
Why does NO turn rapidly into NO2 in the atmosphere?
It is very reactive as it is a radical, although NO2 is still a radical it is more stable.
What are the main ways NO are produced?
Combustion processes in vehicle as well as thunderstorms.
Out of NO, NO2, and N2O, which are toxic gases?
NO and NO2.
What is the main use of the gas N2O?
It is used as a mild anesthetic, also known as laughing gas.
What are two kinds of nitrate ions involved in the nitrogen cycle?
Nitrate(III) ion and nitrate(V) ion.
What is the formula of a nitrate(III) ion?
NO2-
What is the formula of a nitrate(V) ion?
NO3-
What is the sequence of nitrogen reduction from nitrate(V) ions, include the oxidation state at the bottom for each one?
NO3- → NO2- → NO → N2O → N2
(+5) (+3) (+2) (+1) (0)
In both nitrate(III) and nitrate(V), how is the negative charge created?
By alternating double bonds, cause by the electrons being delocalized.
When does the reduction of nitrogen sequence take place?
In conditions where oxygen content is low, anaerobic bacteria breaks it down.
In what conditions are nitrate ions made?
When oxygen is available, made by oxidation of ammonium ions by aerobic bacteria.
What is the process of making nitrates known as?
Nitrification.
What is the equation for the first stage of nitrification for forming nitrate(III) ions?
NH4+(aq) + 1 1/2O2(g) → NO2-(aq) + 2H+(aq) + H2O(l)
What is the equation for the second stage of nitrification where you oxidizing nitrate(III) ion further to nitrate(V) ions?
NO2-(aq) +1/2O2(g) → NO3-(aq)
What are things used to test for nitrate(V) ions?
Sodium hydroxide solution and Devarda’s alloy, e.g. Cu, Al, Zn.
What would be produced if solution contained Nitrate(V) ions?
Ammonia gas.
Why is Devarda’s alloy required for the test?
It acts as a reducing agent.
What is a test you can do for ammonia gas?
It turns damp red litmus paper blue.
How can you test for ammonium ions?
Sodium hydroxide solution is added and gently heated, if ammonium ions are present, ammonia gas will form.
