Jawaban BAB I

JAWABAN SOAL
1. Satuan sel emas adalah kubus pusat muka (fcc). Berapa jumlah atom menempati satu satuan sel emas, dan berapa massa satu satuan sel ini?
Jawaban :
Au (Mr = 197)
Jumlah atom 4
Mol = 4/6,02 . 1023 = 0,664 . 10-22
Massa = mol x Mr
= 0.664 .10-23 x 197
= 130,897 . 10 -23
= 1,3 . 10 -21
Jadi, massa satuan sel emas adalah 1,3 . 10-21 gram
2. Panjang satuan sel adalah o,4079 nm. Hitung volume satu satuan sel kubus dengan informasi dari soal no 1 tersebut; hitung pula rapatan teoritis emas ini?
Jawaban :
a = 0,4079 nm = 0,4079 . 10-7 cm
V = (0,4079 . 10-7 )3
= 6,787 . 10-23 cm3
Ρ = Zn.M/NV
= (4 x 197)/( 6,02 . 1023 . 6,787 . 10-23 )
=19,289 gram/ cm3
=19,29 gram/ cm3
3. Panjang satuan sel intan terukur adalah 0,3567 nm. Hitung volume satuan sel kubus intan (dalam cm3) dan hitung rapatan teoritis intan jika massa satu atom karbon adalah 12,01 g mol-1 ; bandingkan hasilnya dengan rapatan intan terukur pada 250C yaitu sebesar 3,513 g cm3.
Jawaban :
R intan = 0,3567 . 10 cm
Volume = 10
Ρ pada 25 0C = 3,513 g cm3
Ρ = Zn.M/NV

Cobalt As a Blue Glass Pigmen

Abstract

Cobalt is a bluish gray element that have several function or advantages. Among as a blue coloring permanently on glass/porcelain glass, also pottery, tiles, and drying agents for paints.

Cobalt glass is a deep blue colored glass prepared by adding cobalt compounds to the molten glass when produced. Addition of pyridine to cobalt(II) chloride in ethanol can produced blue complexes, having the composition [CoCl2 pyr2 ]CN4 .Blue glass has sun light adsorb power average 55%. The effects are room temperature more cold, and air conditioner work less. Beside that blue glass can forward the light less than the transparent glass. It makes the room become more comfortable because blue glass will decrease the light which enter to the room.

Cobalt can give color an a glass, so will increase esthetic value. Cobalt also decrease hot room effect so the room temperature become more cold.