water 2 Flashcards
what are solutions?
HOMOGENOUS mixtures of two or more components/ALL solutes
AND solvent
what are 3 factors affecting solubility?
- SOLUTE molecule structure/polarity
- Temperature
- Pressure
what is vitamin A, C soluble in?
vitamin A: non-polar (fat soluble)
vitamin C: polar (water soluble)
when can solutions form from a molecular point of view?
when SOLUTE and SOLVENT both POLAR or both NON-POLAR
what is vitamin C also called?
ascorbic acid
what are polar solutes referred to?
as “HYDROPHILIC”
what is hydrophilic molecules?
“attracted to water” and dissolve in it
what are non-polar solutes referred to?
“HYDROPHOBIC” as water prefers to interact with itself than it does with them
what is hydrophobic molecules?
NOT “attracted to water” and do NOT dissolve/mix in it
are benzoic acid and acetic acid soluble in water? explain why.
Both benzoic acid and acetic acid have the same “carboxylic acid” (-COOH) group, which is POLAR and helps a molecule dissolve in water. However, benzoic acid also has a larger NON-POLAR benzene portion and is therefore not soluble.
what are soaps made of and what are composed of?
made up of FATTY ACID molecules.
Fatty acids are composed of:
1. a HYDROPHILIC head (polar -COOH carboxylic acid group)
2. a HYDROPHOBIC tail (non-polar hydrocarbon chain, referred to as a HYDROCARBON)
how do fatty acids align themselves to and what do they form?
- maximize hydrogen bonding between hydrophilic (-COOH) heads and water.
- maximize interactions between hydrophobic tails (keep all the HYDROCARBON tails together)
Form what is known as MICELLES
in general, hydrophobic or hydrophilic are molecules whose interactions with water are more favourable?
hydrophilic molecules than their interactions with non-polar substances such as HYDROCARBONS made up primarily of C-C and C-H bonds
in general, hydrophobic or hydrophilic are molecules whose interactions with water are less favourable and explain?
Interactions between water and non-polar
(HYDROPHOBIC) molecules not as strong as water-water or water-polar solute interactions
assuming water is your solvent, how do you think solubility of a solid in water is affected by
changes in temperature?
Solubility of solids in water often INCREASES with increasing temperature.
However, solubility of some solids in water DECREASES with increasing temperature!
e.g., solubility of Na2SO4 (sodium sulfate) and Ce2(SO4)3 (cerium sulfate) in water decreases with increasing temperature.
Overall, only way to determine impact of temperature on solubility of a solid is to examine it experimentally!
assuming water is your solvent, how do you think solubility of a gas in water is affected by
changes in temperature?
In general, can say that solubility of gases in
water DECREASES with INCREASING
temperature.
e.g., less oxygen will dissolve in warm water
than cold water, trout need well oxygenated water and live in colder water with higher oxygen concentrations and carp can handle lower oxygen concentrations and can live in warm ponds.
what does pressure influence solubility?
PRESSURE (in other words the amount) of a gas above water’s surface determines frequency of collisions between gas and water’s surface
PRESSURE (or amount of a gas) above water’s surface directly impacts amount of gas in aqueous solution and how fast gas dissolves in water.
Increasing PRESSURE or amount of a gas above the water, increases amount of that gas dissolved in water (since have more collisions between gas and water surface).
give an example of pressure changing the solubility.
e.g., as amount of CO2 above our oceans increases due to human activities, amount of CO2 entering oceans also increases
what one of the biggest environmental threats currently facing is pressure behind?
ACIDIFICATION OF OCEANS:
As amount of CO2 above oceans increases,
ocean’s pH decreases (i.e., oceans become
more acidic)
examples of acids.
hydrochloric acid (HCl) in your stomach, lemon juice, vinegar
examples of bases.
sodium hydroxide (NaOH) in your drain cleaner, soap
what exactly is pH?
p = -log
Therefore,
pH = -log[H+], where [H+] is the concentration or amount of H+
e.g.,
if [H+] increases, pH decreases (acids decrease the pH of an aqueous solution)
if [H+] decreases, pH increases (bases increase the pH of an aqueous solution)
what does working with a log scale imply?
Each time decrease pH by 1 pH unit (e.g., 2 to 1): 10X MORE ACIDIC
Each time increase pH by 1 pH unit (e.g., from 8 to 9): 10X MORE BASIC
what is the advantage of pH scale?
Can work with simple numbers and not “ridiculous” concentrations with all those zeros.
