Aqueous Solutions And Acididity Flashcards
What are the unique physical properties of water?
Its melting point, boiling point, density in solid and liquid phases and surface tension.
What can the unique physical properties of water be explained by?
Its molecular shape and Hydrogen bonding between molecules.
What is the melting point of water?
0°C
What is the boiling point of water?
100°C
What is the freezing point of water?
0°C
What does the melting/freezing/boiling point of water depend on?
Pressure, adding a solute.
How can the boiling point of water be increased?
Pressure, adding a solute.
What is the density of liquid water?
1 g/mL
What does the buoyancy of ice in water suggest?
Solid water (ice) has a lower density than liquid water. Its density decreases as it cools.
Define surface tension.
Cohesive forces between molecules. Molecules at the surface do not have molecules on all sides and adhere more strongly.
Define concentration.
The quantity of solute dissolved in a quantity of solution.
How can concentration be represented?
By the number of moles of the solute per litre of solution (mol/L), the mass of the solute per litre (g/L) and parts per million (ppm).
Define solute.
The soluble substance that is dissolved to make a solution.
Define solvent.
The substance that is able to dissolve the solute in a solution.
Define solution.
A homogeneous mixture (same composition and properties throughout) made up of a solute dissolved in a solvent. A mixture of 2 or more substances in a single phase.
Define saturated solution.
A solution where no more solute is able to dissolve in a solvent.
Define unsaturated solution.
A solution that contains less than the quantity of solute required to saturate it.
Define supersaturated solution.
A solution prepared under certain conditions which contains more solute than is contained in a saturated solution.
Define soluble.
When a solute is able to readily dissolve in a particular solvent.
Define insoluble
When a solute is unable to dissolve in a particular solvent.
Define dilute.
A solution with comparatively little solute dissolved in a solvent.
Define concentrated.
A solution with a high proportion of solute dissolved in a solvent.
Define Brownian motion.
The name given to the random motion of particles in a liquid.
Define gas solution.
A homogeneous mixture of gases, where gases are dissolved in other gases. Eg: air, smoke.
Define solid in liquid.
A homogeneous mixture of a solid or solids dissolved in liquid.
Eg: seawater, cordial.
Define liquid in liquid.
A homogeneous mixture of one liquid dissolved in another. Eg: beer/wine (alcohol dissolved in water), 2 stroke fuel (oil in petrol).
Define gas in liquid.
A homogeneous mixture of a gas dissolved in a liquid.
Eg: soft drinks (CO2 dissolved in water).
Define solid in solid.
A homogeneous mixture of one solid in another.
Eg: coins, solder, bronze, brass (alloys).
Is solubility related at all to the solute?
Yes, some solutes are insoluble and some are soluble, this affects the solubility.
Define compound.
2 or more different atoms chemically combined.
Percent concentration equation.
Define mixture.
2 or more chemicals, mixed but not combined.
Concentration equation (g/L).
Concentration/molarity equation (mol/L).
Concentration equation (ppm).
Number of moles equation (using concentration and volume).
Define dissociation.
The breaking up of a compound into simpler constituents that are usually capable of recombining under other conditions.
Occurs in ionic compounds.
Define ionization.
Where substances dissolve and then react with the water to form ions.
Occurs in covalent molecular compounds
These substances do not exist as ions when not dissolved in water, but when it dissolves in water it dissolves and then ionizes.
Define strong electrolyte.
A substance that exists almost entirely as ions when dissolved in solution.
All soluble ionic compounds and some covalent molecular substances are strong electrolytes.
All strong electrolytes make solutions that are good conductors.
Examples of strong electrolytes.
NaCl, CaCl2, Ca(NO3)2, HCl, HNO3, H2SO4
Why are insoluble ionic solutes considered strong electrolytes?
The small amount of the solute that does dissolve will ionize completely.
Define weak electrolyte.
A substance where only a small proportion of the molecules ionize in solution. The substance will dissolve but it will remain mostly as molecules in solution with few ions.
Examples of weak electrolytes.
HF, CH3COOH, NH3
Define nonelectrolyte.
A covalent molecular substance that dissolves in water but forms no ions at all.
Tend to be non-conductors.
Examples of nonelectrolytes.
Sugar, alcohol
Define precipitate.
The solid product that is sometimes formed when two aqueous solutions containing soluble ionic substances are mixed together.
What does solubility depend on?
Solvation properties of polar substances.
Define solvation.
The attraction of polar solvent molecules to both the anions and cations of the solid.
What makes water an excellent solvent for many ionic solutes?
Its highly polar nature.
Define hydration.
Solvation by water.
Why does hydration occur?
The electrostatic attraction between ions and one side of the water molecule.
Define Arrhenius acid.
A substance that, when added to water, increases the concentration of H+ ions present.
Eg: HCl
Define Arrhenius base.
A substance that, when added to water, increases the concentration of OH- ions present.
Eg: NaOH
Define strong acid.
An acid that almost completely ionizes in solution. Very few acid molecules exist in solution, mostly ions.
Define weak acid.
An acid that exists mostly as molecules in solution with few ions in solution.
Weak acids do not ionize well.
Most acids are weak acids.
Use the double arrow to represent a weak acid partially ionizing
Define strong base.
A base that almost completely ionizes in solution. Very few molecules exist in solution, mostly ions.
Define weak base.
A base that exists as mostly molecules in solution, with very few ions.
Define monoprotic acid.
An acid with only one donatable Hydrogen ion.
Define diprotic acid.
An acid that is able to donate two Hydrogen ions.
Define triprotic acid.
An acid that is able to donate three Hydrogen ions
Define polyprotic acid.
An acid that is able to donate more than one Hydrogen ion
Define universal indicator.
A mixture of several other indicators that produce a range of colours which gradually change as the acidity (pH) of the solution changes.
Can be used as a solution or embedded on a paper strip.
Accompanied by a colour change chart.
Colour of universal indicator.
Define pH scale.
A logarithmic scale of the concentration of H+ ions in a solution, where 1 → 6.9 is acidic, 7 is neutral and 7.1 → 14 is basic.
Autoionization of water equation.
H2O (l) ⇔ H+ (aq) + OH- (aq)
Equilibrium constant equation.
Kw = [H+][OH-] = 1 × 10-14
Square brackets means concentration.
What is the concentration of the Hydrogen ion and Hydroxide ion in pure water or any neutral solution at 25°C?
1 × 10-7 mol/L
What will happen when an acid is added to water and the Hydrogen ion concentration increases?
The Hydroxide ion concentration will decrease.
What will happen when a base is added to water and the Hydroxide ion concentration increases?
The Hydrogen ion concentration will decrease.
pH equation.
pH = -log[H+]
3 physical properties of acids.
Conduct electricity
Taste sour
Turn blue litmus red
Acid + reactive metal → ?
Salt + Hydrogen gas
Acid + Carbonate → ?
Salt + Water + Carbon Dioxide
Acid + Hydrogen Carbonate → ?
Salt + Water + Carbon Dioxide
Acid + Metal Oxide → ?
Water + Salt
Acid + Metal Hydroxide → ?
Salt + Water
Acid + Metal Sulphite → ?
Salt + Water + Sulphur Dioxide
4 physical properties of bases.
Conduct electricity
Taste bitter
Slippery feel
Turn red litmus blue
Base + Ammonium Salt → ?
Ammonia + Water + Salt
Base + Non-metal Oxide → ?
Water + Salt
