Save the Elephants (STE) is a non-profit organisation. It was set up in 1993 by Iain Douglas-Hamilton, and today it is one of the world's largest organisatons to save 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 in to behaviours of elephants, and raising people's awareness through films, televisions and new media sources. So far, it has conducted 335 projects in 40 countries and helped to protect thousands of elephants worldwide.

a. 5CaC2O4+ 2KMnO4+ 8H2SO4 -> 5CaSO4 + K2SO4 + 2MnSO4 + 10CO2+ 8H2O

b. KMnO4 = 2,05 mL*(1L/1000mL)*4,88*10^-4M= 9,994*10^-7 mol

CaC2O4= 9,994*10^-7 mol* 5/2= 2,4985*10^-6mol

Ca^2+= 2,4985*10^-6 mol( vì tỉ lệ mol giữa CaC2O4 và Ca^2+ là 1:1)

Ca^2+= 2,9485*10^-6 mol* 40,08g/mol= 1,001*10^-4g

Ca2+= (1,001*10^-4g/1mL) * (100mL/100mL) * ( 1000mg/1g)= 10,01mg/100mL

( -542,83)+ 2*(-167,16)= -877,15kj/mol

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

- Quá trình oxi hóa: Fe-> Fe3+ + 3e- ( Fe là chất khử)

- Quá trình khử: N5+ + 3e- -> N2+ (HNO3 là chất oxi hóa)

b. 2KMn04 + 10FeSO4 + 8H2SO4 -> 5Fe2(SO4)3 + 2MnSO4 +K2SO4+ 8H2O

-Quá trình oxi hóa: Fe2+ -> Fe3+ +e- ( Fe là chất oxi khử)

- Qua trình khử: Mn7+ +5e- -> Mn2+ ( KMnO4 là chất oxi hóa)