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78 Cards in this Set
- Front
- Back
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what is the purpose of coefficients in a chemical equation?
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represent the # of individual atoms & molecules
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what (s), (l), (g) & (aq) stand for
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s - solid
l - liquid g - gaseous aq - aqueous |
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why is it important that a chemical reaction be balanced
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law of mass conservation -
matter can't be created or destroyed during a chem. reaction |
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why is it important to never change a subscript while balancing an equation?
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it could change the compound's identity
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why don't equal masses of golf balls & ping-pong balls contain the same number of balls?
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they have different masses
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why don't all collisions between reactant molecules lead to product formation?
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molecules must collide in a certain orientation in order to react
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what generally happens to the rate of a chemical reaction with increasing temperature?
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increased
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which reactant molecules are the first to pass over the energy barrier?
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fastest moving molecules
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what term is used to describe the minimum amount of energy required in order for a reaction to proceed?
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activation energy
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what catalyst is effective in the destruction of atmospheric ozone, o3?
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chlorine atoms
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what is the purpose of a catalytic converter?
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to reduce the amount of pollutants entering the atmosphere
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what does a catalyst do to the energy barrier of a reaction?
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lowers
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why are catalysts so important to our economy?
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keep low the prices of:
gasoline, rubber, plastics, pharmaceuticals, automobile parts,clothing, & food grown w/ chem fertilizers |
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436 kilojoules to break a bond, how many released when same bond is formed?
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436 kilojoules
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is there any energy consumed at any time during an exothermic reaction?
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no
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what is released by an exothermic reaction?
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energy
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what is absorbed by an endothermic reaction?
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energy
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as energy disperses, where does it go?
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flows from where it is concentrated to where it flows out (entropy)
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units of entropy?
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K
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how does a catalyst lower the energy barrier of a chemical reaction?
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provides an alternative & easier-to-achieve pathway along which the chemical reaction can proceed
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neutralization - chem/phys change?
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chemical
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do water molecules react with one another?
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yes, but not to any large extent.
when they do react, they form hydronium & hydroxide ions |
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why must a buffer have at least 2 dissolved components?
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one to neutralize acid
one to neuralize base |
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Bronsted-Lowry definition of acid & base
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acid - substance that donates hydrogen ions
base - substance that accepts hydrogen ions |
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when an acid is dissolved in water, what ion does the water form?
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hydronium
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when a chemical loses a hydrogen ion, is it behaving as an acid or a base?
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base
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what is the Lewis definition of an acid & a base?
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acid - donates a positive charge to a lone pair
base - a molecule with a lone pair of electrons accepts a positive charge |
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does salt always contain sodium ions?
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NO
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what two classes of chemicals are involved in a neutralization reaction?
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acid, base
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what does it mea to say that an acid is strong in an aqueous solution?
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little of the acid remains
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what happens to most f the molecules of a strong acid when the acid is mixed with water?
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remain intact in their original, nonionized form
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why does a solution of a strong acid conduct electricity better than a solution of a weak acid having the same concentration
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many ions are generated;
presence of these ions allows for the low of a large electric current |
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which has greater ability to accept hydrogen ions: strong/weak base?
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strong
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is is possible for a chemical to behave as an acid in one instance and a base in another?
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yes - amphoteric
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is water a strong acid or weak acid
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weak acid
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is Kw a very large/small numbr
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very small
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as the concentration of H<3>O+ ions in an aqueous solution increse, what happens to the concentration of OH- ions?
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must decrease
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relative concentrationsof hydronium & hydroxide ions: acid, base, neutral
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acid - hydronium ` hydroxide _
base - hydronium_ hydroxide ` neutral - hydronium = hydroxide |
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what does the pH of a solution indicate?
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acidity of a solution
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hydronium ions concentration increases - pH increase/decrease?
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increase
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what is the product of the reaction between carbon dioxide & water?
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carbonic acid
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how can rain be acidic & not qualify as acid rain?
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rain's usual pH is 5-7
acid rain is lower than 5 |
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wht does sulfur dioxide have to do with acid rain?
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acid rain is created when sulfur dioxide is absorbed by atmospheric moisture
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how do humans generate the air pollutant sulfur dioxide?
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liming
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how does one lime a lake?
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raising the pH of acidified lakes & rivers by adding calcium carbonate
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why aren't atmospheric levels of carbon dioxide rising rapidly based on the increased output of carbon dioxide resulting from human activities?
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oceans neutralze the CO2 by becoming CO2 sinks, therefore CO2 isn't released back into the atmosphere
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what is a buffer solution?
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any solution that resists large changes in the pH
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a strong acid quickly drops the pH when added to water, but not so when added to a buffer solution... why?
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H+ ions produced by the HCl do not stay in the solution to lower the pH b/c they react w/ acetate of sodium acetate to form acetic acid
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do buffer solutions prevent/inhibit changes in pH?
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prevent
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why is it so important that the pH of our bloob be maintained within a narrow range of values?
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cellular proteins will become denatured
LETHAL |
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why does holding your breath cause the pH of your blood to decrease?
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CO2 builds up in your blood stream -> increases carbonic acid -> lowers blood pH
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T/F:
reducing agents are oxidized in oxidation-reduction reactions? |
true
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T/F:
oxidizing agents are reduced in oxidation-reduction reactions? |
true
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LEO the lion went GER
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Lose Electrons - Oxidation
Gain Electrons - Reducation |
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what is recharged in a car battery?
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reactants are regenerated
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is the reaction that foes on in a hydrogen-oxygen fuel cell an example of electrolysis?
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no
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oxygen & chlorine are good oxidizing agents... what does this tell you about their positions on the periodic table?
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a must lie in the same area
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which elements have the greatest tendency to behave as oxidizing agents?
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upper right of the periodic table b/c of tendency to gain electrons
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reducing agent
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any reactant that causes aother reactant to be reduced
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oxidizing agent
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any reactant that causes another reactant to be oxidized
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which elements have the greatest tendency to behave a oxidizing agents?
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upper right of periodic table b/c of tendency to gain electrons
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reducing agent
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any reactant that causes another reactant to be reduced
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oxidizing agent
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any reactant that causes another reactant to be oxidated
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what happens to a reducing agent as it reduces?
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gain of electrons
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what happens to an oxidizing agent as it oxidizes?
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loss of electrons
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what elements have the greatest tendency to behave as reducing agents?
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bottom left hand
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what elements resist either being oxidized or reduced?
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group 18
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what gets reduced as bromine ions on film are oxidized by light?
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electrons reduced o opaque silver atoms
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which microcrystals within exposed film are most susceptible to being reduced by hydroquinone?
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silver bromide
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what chemical is commonly used to stop the hydroquinone-induced development of a photographic image?
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sodium thiosulfate
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what is electrochemistry?
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branch of chemistry concerned wih the relationship between electrical energy &chemical change
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what is electrolysis?
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use of electrical energy to produce chemical change
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what type of rection occurs at the cathode?
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oxidation
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what type of reaction occurs at the anode?
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reduction
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why is oxygen such a good oxidizing agent?
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it is able to pluck electrons from many other elements
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what do the oxidation of inc & aluminum have in common?
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they both form a protective coat that shileds them from further oxidation
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is a metal that is being electroplated given a negative/positive charge?
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negative
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what is iron forced to accept during cathodic protection?
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electrons
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