Malvern Zetasizer Nano Series, Руководство пользователя

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In each molecule of water there are two atoms of Hydrogen (H
2
) and one
atom of Oxygen (O).
Now the atomic weight of hydrogen is 1.008 amu and that of oxygen is
15.999.
Therefore the molecular weight of water is 18.015 i.e.(1.008 x 2)+15.999.
This is a calculation using a known molecular formula and applying the values
from the periodic table.
With the Zetasizer Nano series of instruments the molecular weight can now be
determined by use of
S tatic L ight S cattering ( SLS ) measurement techniques.
This technique will be more explained in chapter 14 - Molecular weight theory.
'
N o t e
. Malvern uses Daltons to identify the molecular weight.
Why do we want to know it?
We need to know the molecular weight, so we can determine how many grams
there are in 1 mole of a substance. The mole being the chemistry standard term
for ‘1 molecular weight’, e.g. one mole of water is 18.015g).
In an application, knowing the molecular weight of polymer compounds will aid
in determining many of their physical characteristics such as density, flexibility
and strength.
What is Zeta potential and Electrophoresis?
Most liquids contain Ions ; these can be negatively and positively charged atoms
called Cations and Anions respectively. When a charged particle is suspended in
a liquid ions of an opposite charge will be attracted to the surface of the
suspended particle.
i.e. - a negatively charged sample attracts positive ions from the liquid and
conversly a positive charged sample attracts negative ions from the liquid.
C H A P T E R 2
Z e t a s i z e r N a n o S e r i e s
P a g e 2 . 5
= +
1.008 1.008
1.008 1.008
15.999
18.015
ILL
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