chemistry calculation

1.
Mole ratio Fe : O
= 72.4/56 : (100 - 72.4)/16
= 1.29 : 1.73
= 3 : 4

Empirical formula = Fe3O4


= = = = =
2.
2C8H18 + 25O2 → 16CO2 + 18H2O
No. of moles of C8H18 = 800/(12*8 + 18) = 800/114 mol
No. of moles of O2 = (800/114) * (25/2) mol
Mass of O2 = (800/114) * (25/2) * (16 *2) = 2807 g


= = = = =
3.
The metal would be copper / mercury / silver / gold / platinum.

與 001 這樣的答案一起投票，簡直是對 002 回答者的侮辱。發問者太不負責任了。

. Egyptian alchemy [3,000 BCE – 400 BCE], formulate early "element" theories such as the Ogdoad. Greek alchemy [332 BCE – 642 CE], the Macedonian king Alexander the Great conquers Egypt and founds Alexandria, having the world's largest library, where scholars and wise men gather to study. Islamic alchemy [642 CE – 1200], the Muslim conquest of Egypt; development of alchemy by Jābir ibn Hayyān, al-Razi and others; Jābir modifies Aristotle's theories; advances in processes and apparatus.[15] European alchemy [1300 – present], Pseudo-Geber builds on Arabic chemistry.[citation needed] From the 12th century, major advances in the chemical arts shifted from Arab lands to western Europe.[15] Chemistry [1661], Boyle writes his classic chemistry text The Sceptical Chymist. Chemistry [1787], Lavoisier writes his classic Elements of Chemistry. Chemistry [1803], Dalton publishes his Atomic Theory. Chemistry [1869], Dmitri Mendeleev presented his Periodic table being the framework of the modern chemistry The earliest pioneers of Chemistry, and inventors of the modern scientific method,[16] were medieval Arab and Persian scholars. They introduced precise observation and controlled experimentation into the field and discovered numerous Chemical substances.[17][verification needed]"Chemistry as a science was almost created by the Muslims; for in this field, where the Greeks (so far as we know) were confined to industrial experience and vague hypothesis, the Saracens introduced precise observation, controlled experiment, and careful records. They invented and named the alembic (al-anbiq), chemically analyzed innumerable substances, composed lapidaries, distinguished alkalis and acids, investigated their affinities, studied and manufactured hundreds of drugs. Alchemy, which the Muslims inherited from Egypt, contributed to chemistry by a thousand incidental discoveries, and by its method, which was the most scientific of all medieval operations."[17]