Solutions, Electrolytes, and Concentrations

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Student’s Name
Professor’s Name
Course Number
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SOLUTIONS, ELECTROLYTES, AND CONCENTRATIONS
Introduction
The term solution refers to a homogenous combination wherein one substance dissolves
another. The solvent is the material that is present in higher concentrations. The majority of
solvents are liquids (Green and Sambrook, 2012). In biological and environmental solutions,
water is notably a common solvent. The solute is the substance that dissolves in a solvent
forming a solution. Gases, liquids, and solids are common types of solutes.
The attraction between two solution components determines a solute's capacity to
dissolve in a given solvent. A solute dissolves more easily in a solvent with the same polarity.
Polar solvents, such as water, are attracted to the partial charges in polar solutes or the charges in
ionic solutes (Falvello et al., 2010). The partial negative charge oxygen atoms in water molecules
are drawn towards the positive sodium ions, while the partially positive hydrogen atoms in water
are drawn towards the negative chloride ions. Nonpolar solutes lack charges or partial charges
that would attract polar water molecules. As a result, nonpolar solutes dissolve more readily in
nonpolar solvents that have equivalent intermolecular interactions to the solutes.
Different solutes have a variety of conceivable behaviors in solution, in addition to
disparities in solubility. Ionic solids dissociate into distinct ions when they dissolve in water,
whereas molecular solutes stay intact. In aqueous solutions, electrolytes are chemicals that create
ions (Beran et al., 2010). The capacity of ions to carry electricity through water is known as ion

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conductivity. When electrolytes are present, electricity can pass through water to complete a
circuit and light a bulb, as illustrated in Figure below.
Strong electrolytes are those that break down into ions and have the highest conductivity
(Robinson, 2006). Weak electrolytes partially dissolve into ions and exhibit modest conductivity,
as demonstrated by the softly lit light bulb. Nonelectrolytes do not form ions (often molecules)
and do not assist in the conductivity of electricity. Electrolytes are essential for cellular activity.
Inside the cells, potassium and bicarbonate ions are present, whereas sodium and chloride ions
are present in the surrounding fluids (Dieffenbach et al., 2003). For cells to operate effectively,
the concentrations and balance of these electrolytes must be maintained.
Figure 1: Comparison of strong, weak, and non-electrolytes in solution
A solution's concentration is the quantity of solute contained in a given volume of solution or
solvent. The amount of solute is frequently expressed as a mass or a number of moles, while the
solution is frequently expressed as a mass or volume. Concentration is measured in a variety of
ways. The mass percent of a solution is represented as %m/m or %w/w where w is weight. The
mass per volume percent of a solution appears as %m/v or %w/v (Agapin et al., 2020). Molarity,
with a symbol of M, is defined as the moles of solute per volume of solution in liters and is a
very common unit for lab purposes.

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mass percent (% m/m) =
mass of solute (g)
mass of solution (g)
× 100%
mass/volume percent (%m/v) =
mass of solute (g)
volume of solution (mL)
× 100%
molarity (M) =
moles of solute
volume of solution (L)
Objectives
1. To explore the conductivity of aqueous solutions of various solutes and to determine the
concentration of a solution.
2. To determine the effect of the number of ions in a compound’s formula on the
conductivity of its solution
3. Identify the electrolytes present in a solution from the formula of the dissolved
compounds.
4. Calculate concentrations in units of molarity, mass percent, and mass/volume percent.
Procedure
The polarity of Solutes and Solvents
Eight test tubes were set up and 3 mL of water was added to four different test tubes. 3 mL of
cyclohexane was added to the other four remaining test tubes. To one polar and one nonpolar
solvent test tube, KMnO4, I2, sucrose, vegetable oil was added, stirred and results were recorded.
Conductivity of Electrolytes
15 mL of each 0.1 M solution were introduced to separate small beakers and the conductivity
electrodes into each solution and observe whether the light bulb has a bright glow, a dim glow,
or no light. And the results obtained.
Concentration

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The mass of a dry evaporating dish was measured followed by 9.90 mL of the NaCl solution into
the evaporating dish. Precisely record the volume of the solution. The contents were re-weighed
again and mass measured. A stem-bath was set up by half-filling a 400-mL beaker with water
and placed on a hot plate and heated to evaporate water after which the contents in the
evaporating dish were heated to dryness. The mass of the remaining contents was measured and
recorded.
Results and Analysis
Table 1: Polarity of Solutes and Solvents
Solute Solubility in water Solubility in cyclohexane Polar or non-polar
KMnO4 No layer formed Layers formed Polar
I2 Layers formed No layer formed Non-polar
Sucrose No layer formed Layers formed Polar
Vegetable oil Layers formed No layer formed Non-polar
Table 2: Conductivity of Electrolytes
Solution Light bulb intensity Electrolyte strength Types of particles
0.1 M NaCl Bright light Strong electrolyte Ions
0.1 M sucrose No light Non-electrolyte Molecules
0.1 M HCl Bright light Strong electrolyte Molecules
0.1 M acetic acid (HC2H3O2) Dim light Weak electrolyte Both
0.1 M NaOH Bright light Strong electrolyte Both
0.1 M NH4OH Dim light Weak electrolyte Both
0.1 M C2H5OH No light Non-electrolyte Molecules

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1. Write the equation for the dissolution of the given solutes in water
HCl(aq): HCl(aq) + H2O(l) ⟶ H3O(aq)
+
+ Cl(aq)
−
NH4OH(aq): NH4OH(aq) + H2O(l) ⟶ NH4 (aq)
+
+ OH(aq)
−
C2H5OH(aq): C2H5OH(aq) + H2O(l) ⟶ C2H5OH(aq)
Concentration
Mass of empty evaporating dish 27.234 g
Volume of NaCl solution 9.90 mL
Mass of dish and NaCl solution 40.329 g
Mass of dish and dry NaCl 30.329 g
Mass of NaCl solution 40.329 − 27.234
= 13.095 g
Mass of dry NaCl 30.329 − 27.234
= 3.095 g
Mass percent 3.095
13.095
× 100% =
Mass/volume percent 3.095
9.90
× 100% = 31.26%
Moles of NaCl
moles =
mass
MW

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=
3.095
58.44
= 0.053 moles
Volume of NaCl solution in liters 9.90
1000
= 9.9 × 10−3
Molarity of NaCl solution
Molarity =
moles
volume
=
0.053
9.9 × 10−3
= 5.35 M
Discussion
Polar solvents are attracted to the partial charges in polar solutes or the charges in ionic solutes
while nonpolar solutes lack charges or partial charges that would attract polar solvents. KMnO4
and sucrose dissolved in a polar solvent and formed layers in non-polar solvents thus were
grouped as polar solutes. I2 and vegetable dissolved in non-polar solvents and formed layers in
polar solvents thus non-polar solutes. Strong electrolytes fully dissociate to individual ions and
have the highest conductivity. Weak electrolytes dissociate partially and exhibit modest
conductivity, while non-electrolytes do not form ions. NaCl, HCl, and NaOH are strong
electrolytes as they produced bright light. Weak electrolytes were acetic acid and ammonium
hydroxide because of the dim light. Sucrose and ethanol were non-electrolytes as there was no
light. Concentration is the quantity of solute contained in a given volume of solvent. Calculation
of the solvent involved calculation of the mass of solute 13.095 g. Using the molecular weight of
NaCl of 58.44g/mol the calculated moles were 0.053 moles. Given that the volume of NaCl in
liters is 9.9 × 10−3
𝐿, the concentration of NaCl used in the experiment was determined to be

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5.35 M. The mass percent of a solution m/m% and mass per volume percent m/v% of NaCl was
23.63% and 31.26% respectively.
Conclusion.
The purpose of the experiment was to determine the conductivity of aqueous solutions of various
solutes and to determine the concentration of a solution. Different types of compounds or
molecules showed different characteristics. Polar and non-polar compounds dissolved in polar
and non-polar solvents respectively and formed layers if no dissolving took place. Different
compounds dissociate in various degrees in solvent thus strong, weak, and non-electrolytes.
Determination of concentration of a solution necessitates knowing its mass and the number of
moles of the solvent. The concentration of the solvent can be represented as percent mass by
mass m/m% or w/w% and mass per volume percent of a solution m/v or %w/v.

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Works Cited
Agapin, Julienne Stephanie. "Laboratory Manual For General Chemistry 1." Available at SSRN
3666182 (2020).
Beran, Jo Allan. Laboratory manual for principles of general chemistry. John Wiley & Sons,
2010.
Dieffenbach, Carl W., and Gabriela S. Dveksler. PCR primer: a laboratory manual. No. Ed. 2.
Cold Spring Harbor Laboratory Press, 2003.
Falvello, Larry R., ed. Techniques in inorganic chemistry. CRC Press, 2010.
Green, M. R., and J. Sambrook. "A laboratory manual." John Inglis 2012 (2012).
Robinson, Paul. Laboratory Manual. Pearson, 2006.