Test 1 (1 - 12) Flashcards
What is a solution?
A solution is a mixture in which one substance called the solute is uniformly dispersed in another substance called the solvent. Almost always a liquid which is called homogenous.
What is Diffusion?
process where particles of liquid, gases, or solid mix as the result of their spontaneous movement caused by thermal agitation and in dissolved substances move from a region of higher to one lower concentration.
Solvent classification, what is it divided into?
Examples of organic solvents
- Hexane
- Benzene
- Methanol
- Ethanol
- Acetone
- chloroform
Examples of inorganic solvents
- Water
- Liquid ammonia
- Hydrogen fluoride (HF)
- Sulphuric acid (H2SO4)
What is a protic solvent? Examples
Protic solvent: Contain in their structure a labile hydrogen atom which can form a hydrogen bond or can be donated to other reagents present in the solution
Examples:
- Water
- Methanol
- Acetic acid
- Isopropanol
What is an aprotic solvent? Examples
Aprotic solvents: Can not donate a hydrogen atom
Examples
- Acetone
- Chloroform
- Dimethylformamide
What is a polar solvent? Examples
Chemical compounds with large dipole moments, they contain bonds between atoms with very different electronegativities, such as oxygen and hydrogen
Examples
- Water
- Ethanol
- Acetone
- Isopropanol
- Dimethylformamide
What are non-polar solvents? Examples
Chemical compounds with small or zero dipole moments, they contain bonds between atoms with similar electronegativities, such as carbon and hydrogen
Examples
- Hexane
- Benzene
- Chloroform
Water as a protonic and polar solvent
It is good at dissolving other protic and polar molecules
Water has an electrical dipole moment.
What is the rule for dissolving substances with each other?
Like dissolves like, because there has to be an attraction between the solute and solvent particles
polar + polar
non polar + non polar
What is solvation?
Solvation - is the process of attraction and association of molecules of a solvent with molecules of a solute.
What is hydration?
Hydration – is the process of attraction and association of molecules of a water with molecules of a solute.
Mixture classification
What is a true solution? And its qualities
The particles of solute and particles of the solvent
have similar size → below 1 nm of diameter
Its particles don’t settle
Its particles can’t be separated by filters or semipermeable membranes
What is a suspension? And its qualities
Heterogeneous mixture –> The particles of the solute are large (diameter of 1um), they can often be seen by the naked eye. The particles precipitate if the suspension is allowed to stand undisturbed
Its particles can’t be separated by semipermeable membranes, but they can be by filters
What is a colloid? And its qualities
a solution that has particles ranging between 1 and 1000 nm in diameter, evenly distributed throughout the solution.
Its particles don’t settle
Its particles can’t be separated by filters, but they can be by semipermeable membranes
Colloid classification
Sol - colloidal suspension with solid particles in a liquid.
Emulsion - two liquids.
Foam - many gas particles are trapped in a liquid or solid.
Aerosol - small particles of liquid or solid dispersed in a gas.
Gel – liquid particles trapped in a solid.
What are liophilic colloids?
Strong affinity to dispersing medium
Liophilic (hydrophilic) colloid,Solid particles are solvated (hydrated)
What are liophobic colloids?
Weak affinity to dispersing medium
Liophobic (hydrophobic) colloid
Solid particles are not solvated, they are stabilized by electric charge on their surface
The particles of a colloid remain dispersed indefinitely unless..?
The particles of a colloid remain dispersed indefinitely unless the temperature or chemical composition of the dispersing medium is changed. In this case, the particles will approach all the way into contact, and stick to each other. T
What can coagulation be caused by?
Coagulation can be caused by:
* addition of an electrolyte,
- dehydratation (addition of an acetone or alcohol),
- evaporation or freezing of dispersion medium,
- heating,
- mechanical forces (agitation, shaking).
What is the Tyndall effect?
Tyndall effect - when light is passed through a colloidal solution, the substance in the dispersed phases scatters the light in all directions, making it readily seen.
Properties of colloids – passing through semipermeable membranes
The dispersed particles in a colloid are unable to pass through the membrane.
What is Raoult’s Law(Decreasing Vapor Pressure)?
the vapor pressure of the solvent decreases when a solute is added (in simpler English – the vapor pressure of saltwater is less than that of pure water).
Boiling point elevation
the boiling point of a solution is higher than that of the
pure solvent (in simpler English – the boiling point of salt-water is higher than that of pure water).
What is freezingpoint depression?
the freezing point of a solution is lower than that of
the pure solvent (in simpler English – the freezing point of salt-water is lower than that of pure water).
What is osmotic pressure?
the pressure which needs to be applied to a solution to
prevent the inward flow of water across a semipermeable membrane.
What is Osmosis?
A semipermeable membrane allows molecules of the solvent (water) to move through but retains the solute molecules. The net flow of solvent through a semipermeable membrane is called osmosis.
The direction of net solvent flow is always from the side with the lower concentration of solute to the side with the higher
concentration.
What is osmolarity?
a way of reporting the total number of particles in a solution to determine osmotic pressure.
What is an isotonic solution?
There is equal flow of water into and out of the cell.
What is a hypotonic solution?
water flows into the cell by osmosis. The increase in fluid causes the cell to swell, and possibly to burst
What is a hypertonic solution?
Water flows out of the cell by osmosis. The cell shrinks.
Chemical equilibrium
where the rate of the forward reaction is equal to the rate of the reverse reaction.
Equilibrium constant
Large equilibrium constant
Small equilibrium constant
What is Le Chatelier’s equilibrium principle?
If a system at equilibrium is subjected to a small change the
equilibrium tends to shift so as to minimize the effect of the
change.
if you add more reactants more products will be made
if you add more products more reactants will be made
What is dissociation?
salt dissociates in water into charged particles – ions
(Arrhenius theory) What is an acid?
any substance which delivers hydrogen ion (H^+) to the solution.
(Arrhenius theory) What is a base?
any substance which delivers hydroxide ion (OH^-) to the solution.
(Arrhenius theory) How does a neutralization work?
Acids and bases neutralize one another because the hydrogen ion and the hydroxide ion combine with one another to form water
Problems with Arrhenius theory
All salts in his theory produce solutions that are neither acidic or basic. This is not the case, we can have salts produce slightly more acidic or basic solutions.
The need for hydroxide as the base - some bases don’t have a hydroxide
The hydrogen ion doesn’t exist for very long in water. No matter how strong the acid.
(Brønsted-Lowry) What is an acid?
acid is a substance that donates H+
(Brønsted-Lowry) What is a base?
base is a substance that accepts H+
According to the brønsted - lowry theory water acts?
Water acts as a base. And there are no free H^+ ions freely existing in it. instead it bonds with water to create H3O^+
(Brønsted-Lowry) Conjugate acid-base pairs
A conjugate acid-base pair consists of molecules or ions related by the loss of one H+ by an acid, and the gain of one H+ by a base.
Dissociation constant for weak acids
Dissociation constant for weak bases
