lec.1

Chemistry
Lecturer:
Krasnikova Olga Vladimirovna,
Associate Professor of the
Department of General Chemistry,
Privolzhsky Research Medical
University, Russia
For work we will use the website of
distance education (СДО)
1. We find in the Google browser - CDO PIMU (СДО ПИМУ)…
2. Go to the tab «PIMU Distance
Education Portal»
«Портал дистанционного
образования ПИМУ"
3.We go to your personal
account. We type our username
and password.
4. Scroll down the department
names and find the general
chemistry department (ОБЩАЯ
ХИМИЯ)
5.Click on the GENERAL
CHEMISTRY (ОБЩАЯ ХИМИЯ) tab
6. Our course - CHEMISTRY
7.Visit the “Notice" section every
day.
8.Also, each topic has a section - Answers of
students. At each lesson you will be given
tasks and you must attach your answers in
this section.
IMPORTANT!!!
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1. After each lesson, complete the task and attach it
to the CDO until 21.00 of the current day.
2. If there is no answer, the student receives a mark
of 2
3. You cannot skip classes. Every lesson we have a
roll call.
4. Lesson starts at 8.00 on Tuesdays
5. You can get a mark for an exam automatically - if
you have not missed a single lesson and have
attached all the answers on time.
IMPORTANT!!!
You need to write all the important
information from each slide from your
exercise book.
TOPIC: Solutions. Ways of expressing
concentration of solutions.
1. SEMINAR.
1.1. Ways of expressing concentration of solutions
(mass fraction, molarity, molality, molar concentration
of the equivalent, titer).
1.2. Preparation of a solution of a given
concentration.
A solution is a homogeneous mixture of particles- ions, atoms, or moleculesof two or more different substances. Homogeneous in this definition means that
the properties and the appearance of all parts of the solution are uniform.
That is, no boundary between particles is visible with or without the aid
of instruments. In a solution, the particles are of atomic, molecular, or ionic size.
Solutions are usually
discussed
in terms of solvent and solute.
In general, the substance
present in the
greater amount is referred
as the solvent,
while the other substance is called the solute.
The concentration of a solute is the amount of solute dissolved in a given
quantity of solution.
The concentration of a solution is
determined by the amount of
solute present in a
definite mass
of the solvent at a particular
temperature.
1. Mass percentage (sometimes is called weight percentage) of
solute is the mass of solute per 100 parts of total, by mass.
That is,
Where:
is the mass fraction of substance X;
m(solute) is the mass of the solute substance X (kg, g);
m(solution) is the mass of the solution (kg, g).
5.00 g NaCl dissolved in 97.0 g of water
2. Molarity
The concentration is commonly called the molarity, abbreviated C(X).
Molar concentration C(X) is expressed in mol/L.
The molar concentration is calculated by the equation:
Where: n(solute) is the moles of a dissolved substance, mole;
m(solute) is the mass of a dissolved substance, kg or g;
V (solution) is the volume of a solution, liter.
Molar mass according to the
periodic table, add up the relative
atomic masses. Hydrogen 1,
chlorine 35.5, total 36.5 grams per
mole
The notions of equivalent and factor of equivalent are widely used in chemistry.
The equivalent of a compound (substance) is such an amount of
substance that reacts without any residue with one equivalent of hydrogen
or in general with one equivalent of any other substance in an exchange reaction
or it transfers one electron in an oxidation – reduction reaction.
Factor of equivalent fequiv(X) is a number, showing which part of the substance
(X) equivalent reacts with one hydrogen ion in a given acid – base reaction or
with one electron in a given oxidation-reduction reaction.
Factor of equivalent is calculated on the basis of stoichiometry of
a given reaction by the equation:
acid
base
3. Molar concentration of equivalent
(normality).
The notion of molar concentration of the equivalent is used for solutions.
The molar concentration of the equivalent, sometimes called normality
of a solution is calculated by the equation:
=М (X)*1/z
r
4. Titer
The titer of a solution is denoted by T(X).
The titer shows what mass of a substance (X) is contained
in 1 mL of its solution.
The unit is g/mL.
The titer of a solution can be calculated by the equation:
1/3 H3PO4
homework
1.
What volume (in mL) of 40% H3PO4 solution (ρ=1,25 g/cm3)
is necessary to prepare 400mL of 0,25N of phosphoric acid
solution (ρ=1g/cm3)?
2.How many grams of K2SO4 are necessary to prepare 100mL of
0,1N K2SO4 solution? Calculate the mass fraction of K2SO4 in
the obtained solution (density of the solution = 1,0 g/cm3).
3. The mass of oxalic acid crystalline hydrate H2C2O4∙2H2O
(3,1547g) was dissolved in a volumetric flask of 750mL. Calculate
the molality, normality and titer of this solution.
4.Solve the test - Initial level