Khimiya, Volume 14, Issue 6
(2005)
Khimiya. 14, 522-528 (2005):
Abstract. This
article grounds the necessity of the knowledge about the technological models of the
explanation in the chemistry teaching. There is a model of the deductive explanation of
the facts and a model of the inductive explanation as well which are both used in the
chemistry teaching.
References: 4
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Khimiya. 14, 529-542 (2005):
Abstract. The results of the pre-testing of 12th
grade students with two 50 items multiple-choice tests are presented and discussed. Both
tests are reliable and valid with respect to the intended learning outcomes but differ in
their overall difficulty. Item analysis data outline a great number of good quality items
and detect specific flaws. An accumulation of such information is a base to construct an
item bank for secondary school graduation examinations.
References: 5
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Khimiya. 14, 558-566 (2005):
Abstract. A simple and sensetive
kinetic-spectrophotometric method is proposed for the determination of ultratrace amounts
of vanadium. The method is based on the catalytic effect of vanadium (IV) or vanadium (V)
on the oxidation of methylthymol blue by potassium bromate in sulfuric acid media at 25 C.
The reaction was monitored spectrophotometrically by measuring the decrease in absorbance
of methylthymol blue solution at 440 nm. The calibration curve obtained by fixed-time and
slope method for V(IV) at the range 0.5 - 150.0 and 5.0 - 100.0 ng/ml and for V(V) at the
range 2.0 - 150.0 and 5.0 - 100.0 ng/ml of vanadium, respecctively. Using fixed time and
slope methods, detection limits obtained 0.3 and 3.2 ng/ml of vanadium (IV) and 1.4 and
3.5 ng/ml vanadium (V), respectively. The proposed method was found to be relatively
selective in the presence of foreign ions and was applied successfully to determination of
vanadium in milk powder and rice. Recovery experiments have also been performed for
natural water samples; excellent results were obtained.
References: 22
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Khimiya. 14, 571-581 (2005):
_________________________________________________
Abstract. Hopefully
all the papers in the field of History and Philosophy of Chemistry (HPC), published in
2004, are listed in the present bibliography. This reference list contains 97 articles in
32 scholarly journals. A list of 52 academic journals, opened for such kind of articles,
is presented.
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Khimiya.
14, 582-584 (2005):
[A]ny student or
newcomer to the field of 31P NMR should find this handbook indispensable. The experienced
NMR spectroscopists should find it a helpful addition to their libraries. Possible new
edition of the book would benefit from the supplement of more discussion on 31P-1H and
31P-13C coupling constants (Vassilev, 2005)
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