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how many hydrogen molecules can bond with water?
what is cohesion?
the hydrogen bonds that hold a substance together.
contributes to the transport of water and dissolved nutrients against gravity in plants.
- the attraction between different kinds of molecules
- the clinging of one substance to another
eg: the adhesion of water to cell walls by hydrogen bonds helps counter the downward pull of gravity
What is surface tension?
the measure of how difficult it is to break the surface of a liquid.
how does water moderate air temperature?
by absorbing heat from the air that is warmer and releasing the stored heat into the cooler air
what is kinetic energy?
the energy of movement
the faster a molecule moves, the greater its kinetic energy
Heat is a form of energy
What is temperature?
A measure of heat intensity that represents the average kinetic energy of the molecules. Regardless of volume
what is a unit of heat called?
a calorie (cal)
what is a calorie?
the amount of heat it takes to raise or lower the temperature of 1g of water by 1c
what is specific heat?
the amount of heat that must be absorbed or lost in order for 1g of a substance to change its temp by 1c
what is waters specific heat?
1 calorie/ gram/ celsius
how do you break hydrogen bonds in water?
heat needs to be absorbed
what happens when hydrogen bonds form in water?
heat is released
what is the relevance of waters high specific heat to life on earth?
- a large body of water can absorb and store huge amounts of heat from the sun in the day and summer. and only warm up a few degrees
- at night and winter the cooling water cam warm the air
what happens with evaporative cooling?
the increase in the kinetic energy can mak the molecules break free of hydrogen bonds and enter the air in a gas state
the quantity of heat a liquid must absorb for 1g to be converted from liquid to gas
- heat of vaporization
- and emergent property caused by the breaking of hydrogen bonds
what is a solution
a liquid that is a completely homogeneous mixture of 2 or more substances
a solvent is.....
the dissolving agent of a solution
a substance that is dissolved into a solution
what is the name of a solution where water is the solvent
an Aqueous solution
what is molecular mass?
the sum of all the masses of all the atoms in a molecule
the number of moles of solute per litre of solution
when a hydrogen atom participating in a hydrogen bond between 2 water molecules shifts from one molecule to the other what happens?
- the dissociation of water molecules
- the hydrogen atom leaves an electron behind and a
- hydrogen ion is actually transferred.
- (h+) a single proton with a +1 charge
- the water molecule that lost a proton is a hydroxide ion charge of -1 (OH-)
- the proton binds to the other molecule making it a hydronium ion (H30+)
what is an acid?
a substance that increases the hydrogen ion concentration of a solution
when acids dissolve in water they donate additional H+ to the solution
a substance that reduces the hydrogen ion concentration of a solution
solution with higher concentration of OH- than H+
OH- and H+ are equal
- a measure of hydrogen ion concentration egual to
- ranging from 0 to 14
pH declines as H+
substances that minimize the changes in the concentration of H+ and OH-
in a solution
how do buffers minimize changes in the pH in a solution?
accepting hydrogen ions from the solution when there's too much and
donating hydrogen ions to the solution when they have been depleted.
how does a hydrogen bond form?
when the slightly negative charge oxygen of one water molecule is attracted to the slightly positive charge of hydrogen of a nearby molecule
basis for waters unusual properties
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