Save the Elephants (STE) is a non-profit organisation. It was set up in 1993 lain Dougla-Hamilton, and today it is one of the world’s largest organisations to elephants worldwide. It aims to make sure elephants do not die out and protect the habitats in which elephants are found. Much of the work of STE focuses on stopping the illegal hunting of elephants especially in Africa and Asia, working together with scientists and experts to conduct research on behaviours of elephants, and raising people’s awareness through films, television and new media sources. So far, it has conducted 335 projects in 40 countries and helped to protect thousands of elephants worldwide.

Biến thiên enthalpy của quá trình= -542,83 + 2.(-167,16) - (-795,0) = -82,15 kJ

a) Chất oxi hóa : HNO3 

Chất khử : Fe

Quá trình oxi hóa : Fe ---> Fe+3 + 3e x 1

Quá trình khử N+5 + 3e ---> N+2 x 1 

Fe + 4HNO3 ----> Fe(NO3)3 + NO + 2H2O

b) Chất oxi hóa : KMnO4

Chất khử : FeSO4

Quá trình oxi hóa : 2.Fe+2 ---> 2.Fe+3 + 2e x 5

Quá trình khử : Mn+7 + 5e --> Mn+2 x 2

 2KMnO4 + 10FeSO4 + 8H2SO4 → 5Fe2(SO4)3 + 2MnSO4 + K2SO4 + 8H2O.