Chemistry Reference
In-Depth Information
8.2.4 Nutrition: Example “Table Salt”
Table salt
“
iodate type
” (E8.6): In today's table salts, in addition to the usual
sodium chloride, often minerals in small concentrations are mixed, such as calcium
carbonate, sodium phosphate, or sodium iodate (“iodine salts”). They serve not only
as supplementary nutrients (promotion and preservation of the teeth) but also as a
technical medium to improve the flow ability. Mixing sodium iodate solution first
with an acid and afterward with colorless potassium iodide solution, the mixture
produces brownish-colored iodine precipitation:
IO
3
ð
5I
ð
6H
þ
ð
aq
Þþ
aq
Þþ
aq
Þ!
3I
2
ð
aq, brown
Þþ
3H
2
O
RR
If the concentration of iodine is too small after using table salt and no brown
color appears, starch solution is able to indicate smallest iodine concentrations by
the specific blue color.
8.2.5 Household: Example “Baking Process”
Baking soda
“
sodium bicarbonate type
” (E8.7): For the production of bread and
cake, baking soda is mostly used. It has the task to develop the gases carbon dioxide
and water vapor by heating the mixture: it provides the dough with cavities and
produces loose structure of bread. In most cases, sodium bicarbonate is mixed with
solid citric acid - the gas carbon dioxide forms:
Na
þ
ð
Cit
ð
NaHCO
3
ð
s
Þþ
HCit (s)
!
aq
!
aq
Þþ
aq
Þþ
H
2
O
ð
l
Þþ
CO
2
ð
aq
;
Þ
ABR
g
Baking powder
“
ammonium carbonate type
” (E8.8): Using ammonium carbonate
as baking powder, in addition to carbon dioxide and water vapor also ammonia is
produced. To get rid of this gas after the baking process, cake or cookies must be flat
and ammonia can escape:
ð
NH
4
Þ
2
CO
3
ð
Þ!
þ
þ
CO
2
ð
Þ
ABR
s
2NH
3
(g)
H
2
O (g)
g
8.2.6 Habitation: Example “Fuels for Heating”
Almost all homes are heated by fossil fuels: one either burns wood or coal in a
fireplace or stove, or natural gas from the gas pipeline, or propane or heating oil
from storage tanks near the house. In all cases, the chimney sweep periodically
