Quiz: Polarity and Solubility

Multiple choice: Select on or more answers and click on them to see if they are correct.

1. The solubility of an analyte depends on …
… the pH
… the absorption
… the pressure
… the solvent polarity
… the temperature
… its charge
… the concentration
… its polarity
2. Which of these statements about electronegativity are correct?
With some exceptions, the electronegativity increases from left to the right across the periodic table of elements.
According to the periodic table of elements the electronegativity of carbon is 3.20.
It decreases from the top to the bottom within one group of the periodic table.
The electronegativity of O is greater than that of C.
It describes the tendency of an atom to attract protons.
3. In a chemical bond involving C and O (e.g. ketone), the electrons are …
… attracted by the O atom.
… distributed equally.
… attracted by the C atom.
4. Elements with a fully occupied outer shell (i.e. full valence shell) are …
… non-reactive
… more reactive than halogens
… chemically inert
… highly reactive
5. An ionic bond …
… involves the generation of two oppositely chearged ions.
… is comparable to a covalent double bond.
… consists of two elements with distinct differences in electronegativity.
… involves the transfer of an electron from one atom to another.
… only occurs in the presence of halogens.
6. Which are intermolecular forces?
Dipole-dipole interaction
Ionic bond
Ion-dipole interaction
Covalent bond
7. What is the difference between logD and logP?
The solubility of charged and ionizable molecules is specified by means of logD.
A triphasic solvent system (water, octanol and chloroform) is used to determine logP values.
The solubility of neutral & non-ionizable molecules is specified by means of logP.
LogD is only used to specify the solubility of hydrophobic compounds, whereas logP refers to hydrophilic ones.
The solubility of charged molecules is specified by means of logP.
8. True or false? Valence electrons are …
… electrons of the outermost shell of the element.
… electrons of the innermost shell of the element.
… participate in the formation of a chemical bond.
… are free electrons.

Fill in the gaps. Toggle down to check your results.

1. Molecules possess a specific hydrophobicity/ hydrophilicity, which is expressed as logP or logD value. At pH 7.4 the following molecules have a specific logD value. Find matches between the logD values below and the molecules.

logD_match

logD values: a) 1.94, b) 0.59, c) 2.96, d) 3.95, e) – 3.40, f) -3.40

Solution

1e, 2d, 3c, 4a, 5b, 6f

2. Match the numbers in the brackets with the words below.

Polarity describes (1) within a molecule, which depends on (2) of its contained (3).

a) atoms, b) electrons, c) the electric charge distribution, d) the electrical conductivity, e) electronegativity

Solution

1c, 2e, 3a

3. Match the provided values of electronegativity and numbers of valence electrons of H, C or O with the numbers in the grey or blue bloxes. Use a periodic table of elements for reference.

a) 2.20, b) 4, c) 2.55, d) 1, e) 3.44, f) 6

electronegativity, valence electrons

Solution

1c, 2a, 3e, 4b, 5d, 6f

4. Match the numbers in brackets with the words below.

Unequal (1) of covalent bond forming atoms results in unequal sharing of (2), which results in (3) and (4) charges on (5) ends of the (6). These bonds are therefore called (7).

a) partially positive, b) neutral, c) polar, d) partially negative, e) hydrophobic, f) same, g) electronegativity, h) opposite, i) electrons, j) protons, k) chemical bond

Solution

1g, 2i, 3a, 4d, 5h, 6k, 7c

5. Label the fields by means of the provided selection. Hint: You may use a period table of elements to look up the electronegativity of H and Cl.

dipole

a) δ− (2x), b) dipole-dipole force, c) δ+ (2x), d) permanent dipole (2x)

Solution

1b, 2c, 3a, 4c, 5a, 6d, 7d

6. Devide whether the given solvents are polar or non-polar. Create a table.

Acetonitrile, dichloromethane, water, ethanol, toluene, hexane, chloroform, isopropanol methanol

Solution

polar_nonpolar_solvents_solution

7. Name the structural formulas of polar and non-polar solvents.

Solvents2

Solution

Solvent names

8. Match the numbers in brackets with the words below.

LogD refers to (1) molecules, which contain (2) groups. Hence the molecule´s (3) and thus (4) changes with the (5) of the solution.

a) neutral, b) ionizable, c) hydrophobicity, d) chargeable, e) pH value, f) hydrophilicity, g) temperature, h) solubility

 

Solution

1b, 2d, 3c, 4h, 5e

 

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