Combined Science Chem

1.Titanium can be extracted from titanium(IV) oxide (TiO2). The extraction consists of two step:
1.TiO2(S) --C(s), Cl(g) --> TiCl4(g)
2.TiCl4(g) -- Mg (L) -->Ti(s)
a) Decide whether titanium or magnesium is more reactive. Explain your answer.
b) In a certain experiment, 11.4 g of TiCl4 were allowed to react with excess Mg 2.54 g of Ti were obatined. What was the percentage yield of Ti? (Relative atomic masses: Mg = 24.3, Cl = 35.5, Ti = 47.9)

2.The following set-up was used to determine the empirical formula of an oxide of Cobalt.
http://farm5.static.flickr.com/4021/4586543476_415055c3d2_b.jpg
The experimental results were as follows:
(1)Mass of crucible + lid = 20.49 g
(2)Mass of crucible + lid + cobalt = 23.13 g
(3)Mass of crucible + lid + oxide of cobalt = 24.09 g
a) give a reason why the crucible should be covered with the lid during heating, as shown in the diagram.
b) Coblat-60 is widely used as a medical source. Find the number of protons and number of neutrons of a 60Co atom.
c) Coblat has a hydrated chloride with the chemical formula CoCl2.nH2O. On strong heating, 22.0 g of the chloride produced 9.99 g of water. What is the value of n? (Relative atomic masses: H = 1.0, O = 16.0, Cl = 35.5, Co = 58.9)