Study sets, textbooks, questions
Upgrade to remove ads
Chem exam #2
Terms in this set (110)
Characteristics of liquids
Move more freely
Hard to compress
Expand to edges of container at the bottom
Examples of liquids
Ethanol (in wine)
Why are liquids liquids?
- Individual molecules contain bonds that hold them together (INTRAmolecular)
- Between molecules that are attractive forces (INTERmolecular)
types of atoms
arrangement of atoms
shape of molecule
What bond is an intermolecular force?
Solid to liquid
Liquid to gas
What is normal room temperature?
70-72 F, 22-25 C
We break/don't break bonds when we boil/melt
Do we break intramolecular or intermolecular forces?
Solids have a _______ force than a liquid
What are the three main forces?
What is a dispersion force?
Electrons in molecules are always moving
Movement depends on # of electrons
# of electrons depends on size
Higher mass=stronger force
What bond has a dispersion force?
Covalent bonds (C, N, O, H, S)
What is a dipole-dipole force?
Molecules are clustered in one area
Usually with oxygen and nitrogen that aren't symmetric
Permanent partial charges on molecule
Attract each other
Dipole-dipole forces are stronger/weaker than dispersion forces
What is hydrogen bonding?
Strong dipole interaction
Must be a hydrogen attached DIRECTLY onto a Fluorine, oxygen or nitrogen
Which force has the strongest IMF
What is water?
An UNUSUAL liquid
Characteristics of water
Dissolves lots of things; highly charged compounds
More dense in liquid form than in solid form
Very high boiling/freezing point
Absorbs lots of heat
High surface tension
What are polar compounds?
Other compounds that are polar, esp ones that have oxygen atoms
Dissolved by water!
Does water dissolve salts?
What are salts?
Compounds of charged ions
Sodium chloride is made up of positive sodium ions and negative chloride ions
Because water is so polar, it interacts with ________ and dissolves them
Why is dissolving salt important?
Allows minerals and nutrients to move from the soil to plants
Non-beneficial compounds can dissolve and be transferred to other areas
Which non-polar compounds do NOT dissolve in water?
Oils and gasoline
What is a non-beneficial compound?
Most compounds are more/less dense in solid phase than liquid phase
MORE dense; molecules are closer together in solid phase
Why does ice float in water?
Ice has 0.9340 g/ML and water has 1 g/ML
Why is it important that ice floats in water?
When water freezes, it freezes at the top so there is still liquid under the ice
Life in lakes can still live even if it's below freezing
Why does it take more energy to melt/boil water?
Water is a double hydrogen bonder; there's a wider range of temperature for life that's based on water to exist
Why does water absorb heat?
Because it takes energy to break the hydrogen bonds in water
What is heat capacity?
How much heat a substance can absorb
How much energy is required to raise the temp 1 degree celcius per gram of substance
Why is it important that water absorbs heat?
It helps regulate temps in bodies of water so there aren't large fluctuations from day to night
Can help regulate local climate
Water has a high surface tension because....
Molecules stick together in the liquid and have a strong attraction to each other at the surface of water
When a small object is placed on the water it will float unless it breaks through surface layer
Water will travel up the walls of narrow tuves of polar material (glass/paper) above....
the level of the rest of the liquid
What is an acid?
Turn litmus red
Dissolves metals llike zine and iron, producing hydrogen gas
What forms when acids and bases react together?
Water and salts
Examples of acids
Ascorbic acid (Vitamic C), carbonic acid
What is a base?
Turns litmus blue
Feels slippery on the skin
Reacts with acids to form water and salts
Example of base
Ammonia, baking soda, drain cleaner
An acid ______ a hydrogen ion to another compound
A base ______ accepts a hydrogen ion from another compound
What hydrogen is NOT acidic?
It has one acidic proton so it can be donated
Other important acids
What is hydrochloric acid (HCl)
called muriatic acid (used in swimming pools) and stomach acid
What is sulfuric acid (H2SO4)
a component of acid rain and in car batteries
What is nitric acid (HNO3)
How lightning fixed nitrogen gets to the earth from the atmosphere
What is carbonic acid (H2CO3)
When carbon dioxide dissolves in water; makes soda bubbly
What is phospohoric acid (H3PO4)
Found in lots of cleaning and food producs
What are the two types of bases?
What are metal hydroxides?
Metal plus a hydroxide ion that dissolves to form the ions
- Sodium hydroxide (NAOH- lye)
- Calcium hydroxide (CA OH 2- lime)
What are nitrogenous bases?
Compounds that have a nitrogen that has a lone pair of electrons to accept a proton
- Ammonia (NH3)
- Methyl amine (CH3NH2)
How are acids dangerous?
Acids eat through metal or burn skin at high concentrations
How are bases dangerous?
Bases can be corrosive to skin as well as certain materials like cloth
What does the strength of an acid tell us?
How much it wants to donate
What does the strength of a base tel us?
How much it wants it
What are the important factors in acids and bases?
The concentration of hydronium ions (H3O+) or hydroxide (OH-) in the solution
Low PH means
lots of hydronium
High PH means
lots of hydroxide
What can water dissolve?
Ionic compounds (salts)
Polar carbon containing compounds (polar organic compounds)
What is a solution?
When one compound is dissolved in another
A solution is made up of _______ and ______
solute (lesser amount) and solvent (greater amount)
A solution is NOT a chemical reaction but a ________
mixing of two components; it can be separated
Formula for concentration
amount of solute/amount of solvent
Hot water has more/less solubility
What ions make up hard water?
Calcium (Ca2+) and magnesium (Mg2+); react with other things to form "scale"
Hard water issues
Soap doesn't work well
Leaves residue on hair and skin
What does water softening do?
Removes Mg and Ca ions, exchanges them for another positive ion and replaces them with sodium ions "Ion exchange"
What else can water dissolve?
Polar organic compounds such as :
Degradation products of leaves/animals
Where did water come from?
-Present at Earth formation
- Early organisms that convert hydrogen sulfide and Co2 into water and sulfur
Hydrogen sulfide and Co2 turning into water and sulfur
96.5% of water is in
2.5% of water is in
30.1% of water is in
1.3% of water is in
68.6% of water is in
20.1% of water is in
73.1% of water is in
Ice and snow
Where is most freshwater in the world?
Glaciers/ice caps in Greenland and Antarctica
What are tributaries?
Smaller springs and rivers that combine to form rivers
What body of water do streams and rivers usually flow to?
What is a lake?
a body of water that's in a basin and is surrounded on all sides by land, NOT connected to a sea or ocean
Lakes are often fed and drained by _______ or _______
streams or rivers
Lakes can be formed by glaciation or in _______ _______
What are the three summer lake layers?
Hypolimnion: temp DOESN'T change
What are streams/rivers?
A body of water that flows from a source into the ocean or another river
What are the two pollution sources in lakes and rivers?
What are point sources?
specific spots; factories, mines, sweage plants
What are non-point sources?
Large areas; farms, storm water run-off, golf courses
Characteristics of phosphate pollution
- PO3 3-: a nutrient for algaue and water plants
- Found in water from minerals dissolved by water
- Found in detergents and agricultural fertilizers
What are human sources of phosphate?
- Agricultural run-off: phosphate is applied to fields and absorbed by plants; runs off into local streams, rivers and lakes when it rains
- Detergents: polyphosphate is added to laundry/dishwasher detergent to help with hard water ions; polyphosphate complexes w/ calcium and Mg to keep it from interfering w detergent
Why is excess phosophate harmful?
- it allows extra algae to grow
- algae dies when excess ph is used up
- it sinks to the bottom of the lake and decomposes using up oxygen
- oxygen levels in the water decrease and kill other organisms
What is eutrophication?
Changes due to excess nutrients in water
What are solutions to eutrophication?
- reduce nutrient input in lakes and rivers
control application of fertilizers by reducing amounts and don't apply when heavy rain is expected
- reduce detergent phosphate and monitor phosophate levels
What is mine waste?
When ore is mined, it disturbs the surrounding material and if it contains sulfides it becomes:
2FeS2+7O2+2H2O=2Fe2+ + 4SO4 2-+4H+
When acid comes in contact with other materials it dissolves them (Lead, copper, nickel)
How does mine acid waste get into streams?
the acid becomes neutralized which raises the pH and iron forms iron hydroxide; called Yellow Boy
How does mine acid waste affect streams and rivers?
-low pH kills plants and animals
-iron hydroxide sinks to bottom and suffocates animals
-iron hydroxide at high concentrations turns to gel and makes water thicker
What is the Gold King Mine Disaster?
leaking acid came out of the Gold King Mine
US EPA accidentally released 3 million gallons
Flowed through Colorado, Utah and New Mexico
Effects of the Gold King Mine Disaster
Lead, aluminum and iron turned the river orange
People near were told to have their water tested
Heavy metal waste became insoluble at less acidic pH's
Where can ground water be found?
Gravel, sand and soil
Types of well
pumped well: need a power source
artesian well: groundwater is under pressure and rises to surface
Is ground water cleaner or dirtier than surface water?
Cleaner! Soil removes pathogens and water dissolves minerals as it moves through
Problems with groundwater
How does ground water have a slow recharge?
It takes out more than can be recharged
In high plains water table dropped 30 ,
Farms are abandoned bc cost of water is too high
How does ground water have ground subsidence?
Water is pulled out from aquifer and the ground above can sink or collapse
How is ground water contaminated?
Organic chemicals- BTX
What are the sources of Nitrate Contamination?
Human sewage from septic systems
What are nitrosomines?
Nitrate and amines react in human stomachs
Sources of organic chemicals
Chlorinated solvents: dry cleaning
Sets with similar terms
Biology Chapter 2.1 Water
AP Biology (61-85)
Rules for Chapter 4
Other sets by this creator
Psych Exam #3
Psych Exam #2
Chem Exam 1
Management exam 2