Water & pH Packet #7 Chapter #2. Introduction Most abundant liquid in the world Makes up at least...
-
Upload
allan-davidson -
Category
Documents
-
view
212 -
download
0
Transcript of Water & pH Packet #7 Chapter #2. Introduction Most abundant liquid in the world Makes up at least...
Introduction
Most abundant liquid in the world
Makes up at least half of all living organisms and up to 95% of some species.
75% of earth is submerged in water
Naturally occurring water consists of 99.76% H2O
Wednesday, April 19, 2023
2
Density
Wednesday, April 19, 2023
5
Water has a maximum density at 4ºC This is when water is in a liquid
state The density will be 1.
H2O (l) is more dense than H2O (s)
Water freezes from top downward allowing ice to form at the top
Ice at top can insulate the warmer water below that layer from colder temperatures above
Prevents large bodies of water from freezing solid and allowing the survival of aquatic organisms
Cohesion & Adhesion
Cohesion Attraction of molecules
of the same substance. The hydrogen bonding
allows water to be cohesive
Causes individual water molecules on the top to be drawn inward allowing for the appearance a smooth surface.
Cohesion & Adhesion
Adhesion Attraction of molecules
of different substances. Example of water in a
graduated cylinder.
HW Assignment Define capillary action
and relate it to the concept of adhesion.
Specific Heat
Specific heat is defined as the amount of heat, measured in calories, required to raise the temperature of one gram of a substance by one Celsius degree.
Water has a very high specific heat It takes a long time for
water to heat up.
Solubility
Water is a versatile solvent due to its polarity
Can form an aqueous solution.
Wednesday, April 19, 2023
13
Definitions
Mixture A portion of matter that
can be separated into two or more substances by physical means alone
Substance composed of 2 or more elements or compounds that are mixed together, but are not chemically combined The two substances
can be separated Salt and pepper Sugar and sand
Wednesday, April 19, 2023
14
Definitions II
Solution A homogeneous (of
uniform structure or composition throughout ) mixture of two or more substances, which may be solids, liquids, gases, or a combination of these.
Homogenous mixture Sugar in water (Sugar-
water) One component (Major),
of a solution, is found in a greater amount Solvent
One component (Minor), of a solution, is found in a lesser amount Solute
Wednesday, April 19, 2023
15
Wednesday, April 19, 2023
16The different regions of the polar water molecule can interact with ionic compounds called solutes and dissolve them
Negative
oxygen regions
of polar water
molecules are
attracted to sodium
cations (Na+).
+
+
+
+Cl –
–
–
–
–
Na+
Positive hydrogen regions
of water molecules cling to chloride
anions (Cl–).
++
+
+
–
–
–
–
–
–Na+
Cl–
Figure 3.6
Solubility
“Likes dissolves likes” Polar with polar Non-polar with non-polar
Oil and water are dislikes Water = polar Oil = non-polar
We say that oil and water are nearly completely immiscible The oil is
suspended
Wednesday, April 19, 2023
17
04/19/23 04:10 PM 17
Other Important Points II
Hydrophilic substanceWater lovingHas an affinity for
water
Hydrophobic substanceWater hatingDoes not have an
affinity for water
Wednesday, April 19, 2023
18
pH
The pH scale will tell us how willing a compound is in giving hydrogen ions (H+)
04/19/23 04:10 PM
20
pH—Acid & Base Reaction
Bronsted-Lowry Acid A substance that donates a
hydrogen ion (H+) An acidic solution has a
higher concentration of H+ than pure water and have pH values below 7
Bronsted-Lowry Base A substance that accepts a
hydrogen ion (H+) A basic, or alkaline
solution, contain lower concentrations of H+ than pure water and have pH values above 7.
04/19/23 04:10 PM
21