The Chemical Industry

dot and cross diagram of ammonium

dative covalent bond bc ammonia has a lone pair

what is the nitrogen cycle and why is it useful

nitrogen is very unreactive so it can’t be used directly by plants to make proteins

nitrogen oxide, nitrogen dioxide and dinitrogen oxide: appearance and where it comes from

NO- colourless, turns to brown NO₂ in air, from combustion in engines, thunderstorms and denitrifying bacteria

NO₂- brown gas, from oxidation of NO in atmosphere

N₂O- colourless gas, formed by denitrifying bacteria

test for nitrate (V) ions, and ammonium ions

nitrate(V): warm with Devarda’s alloy and NaOH, test gas w damp red litmus, if it turns blue it is present

ammonium: warm w NaOH, if damp red litmus paper turns blue it is present

this is because both processes release ammonia which is basic so turns litmus paper blue

rate of reaction vs product yeild

product yeild depends on Kc/equilibrium, but rate of reaction is always increased by increasing temperature and pressure- energy/cost/safety issues. May have to compromise between product yeild and rate of reaction

rate equation

shows how fast reactants are converted into products. This depends on conc of reactants, and rate constant. Units are mol dm^-3 s^-1

A+B→C+D

rate equation= k[A]^m + [B]ⁿ

m and n = order 0,1, or 2, overall order= m + n

k- rate constant: this is constant when the temperature is constant. its units vary

zero order

• conc of this species has no effect on rate

• horizontal line

• rate = k

first order

• conc of the species is directly proportional to rate

• doubling conc doubles rate

• rate = k[A]