CHEM ch 9,10,11 (after exam 3)
How much energy is consumed in breaking apart the chemical bonds of the reactants in the reaction between hydrogen and oxygen to form water? (HH 436 kJ/mol; O=O 498 kJ/mol; HO 464 kJ/mol)
-remember: must balance first -HH (436+436) plus O=O (498) -add all the reactancts^ up and you get +1370 kJ/mol
catalysts
-speeds up the rate of a reaction -lowers the activation energy for a reaction -chemically unaltered during the chemical reaction and therefore is reused over and over again in a reaction -biological catalysts are known as enzymes
Entropy
A measure of an amount of energy that has been dispersed. Wherever there is a spreading of energy, there is a corresponding increase in entropy
reaction rate
A measure of how quickly the concentration of products in a chemical reaction increases or the concentration of reactants decreases
hydroxide ion
A polyatomic ion made by removing a proton (hydrogen ion) from a water molecule.
Neutralization
A reaction between an acid and a base
Base
A substance that accepts hydrogen ions or donates electron pairs
Thermodynamics
An area of science concerned with the role energy plays in chemical reactions and other energy-dependent processes
Salt
An ionic compound made from the reaction between an acid and a base
Acid
Any substance that donates hydrogen ions or accepts electron pairs
catalyst
Any substance that speeds up the rate of a chemical reaction without itself being consumed by the reaction
BAAD
Bases Accept, Acids Donate protons/hydrogen atom missing its electron
What is the difference between the coefficient and the subscript numbers used in a balanced chemical equation?
Coefficients quantify molecules while subscripts quantify atoms.
A reaction that absorbs energy is called what?
Endothermic
which molecule is acting as an acid? H2O+NH3--> OH(-)+NH4(+)
H2O
what is the main characteristic of a strong acid?
It is completely dissociated in water.
What happens to a catalyst once it serves to catalyze a chemical reaction?
It is regenerated and available to catalyze more reactions.
New car engines built using ceramics rather than metals operate at much higher temperatures. This gives them better fuel efficiencies and fewer hydrocarbon exhausts. What about nitrogen monoxide exhausts?
More nitrogen monoxide is produced.
which molecule is acting as a base? H20+NH3-->OH(-)+NH4(+)
NH3
should the following reaction be endothermic or exothermic? O2NNO2--->O2N+NO2
No calculations are necessary. Endothermic because it involves only the breaking of a chemical bond.
Should all sodium ions be cut out of our diet for better health?
No, no, no! We need a balance of sodium and potassium ions.
Do all collisions between reactants lead to products?
No, there also needs to be sufficient orientation of the particles.
How many ions are formed when a weak acid is added to water?
Not as many as are formed when a strong acid is added to water.
The mole is a unit of what?
Numbers of particles.
Which molecule is acting as a base? OH(-)+NH4(+)—>H2O+NH3
OH(-)
difference between an exothermic and endothermic reaction?
One releases energy and the other consumes it.
What is the catalyst in a car_s catalytic converter?
Platinum or rhodium.
Law of Mass Conservation
Principle that states that matter is neither created nor destroyed during a chemical reaction - atoms merely rearrange, without any apparent loss or gain of mass, to form new molecules
neutral
Said of a solution in which the hydronium-ion concentration is equal to the hydroxide-ion concentration
acidic
Said of a solution in which the hydronium-ion concentration is higher than the hydroxide-ion concentration
basic
Said of a solution in which the hydroxide-ion concentration is higher than the hydronium-ion concentration. Also sometimes called alkaline
bond energy
The amount of energy required to pull two bonded atoms apart, which is the same as the amount of energy released when the two atoms are brought together into a bond
What happens to the corrosive properties of an acid and a base after they neutralize each other?
The corrosive properties are neutralized because the acid and base no longer exist
Where does the net energy released in an exothermic reaction go?
The energy goes into increasing the speeds of reactant atoms and molecules and often into electromagnetic radiation such as light
Which is heavier, a liter of water vapor or a liter of gaseous nitrogen?
The liter of nitrogen is heavier.
Activation energy
The minimum energy required for a chemical reaction to proceed
What is the relationship between the number of ions in solution and how well it conducts electricity?
The more ions, the better it conducts electricity.
Avogadro's number
The number of particles-6.02x10^23 contained in one mole of anything
What has to happen in order for there to be a reaction between two reactants?
The reactants need to collide.
What do all salts have in common?
They are ionic products of the reaction between an acid and a base.
Why is the chemistry of sodium hydroxide and potassium hydroxide so similar?
They both consist of hydroxide ions.
Why can clouds of condensed water vapor can be seen coming from the exhaust of cars on cold days?
Water vapor is produced as gasoline combusts.
Is it possible for a reactant also to be a product?
Yes, a product of one reaction can be used as the reactant of another reaction.
Do physical changes, like chemical changes, involve the absorption or release of energy?
Yes, because particles are being separated from each other.
Is it possible for water to behave as both an acid and a base?
Yes, since the water can donate or accept a hydrogen ion.
can an acid and a base react to form an acid?
Yes. An acid and a base can react to form an acid if the acid is a strong acid and the base is a weak base.
how is a catalyst different from a chemical reactant
a catalyst is not used up during a chemical reaction. Instead, it is released as its original self. The catalyst can then serve to catalyze more reactions. A chemical reactant, by contrast, is consumed during a reaction as it is transformed into a chemical product
Amphoteric
a description of a substance that can behave as either an acid or a base
pH
a measure of how acidic or basic a solution is, equal to the negative logarithm of the hydronium-ion concentration
Entropy is
a measure of the dispersal of energy.
hydronium ion
a polyatomic ion made by adding a proton (hydrogen ion) to a water molecule
The positively charged hydrogen ion is
a proton without an electron
buffer solution
a solution that has the ability to resist large changes in pH, made from either a weak acid and one of its salts or a weak base and one of its salts
true statement about a base
a strong base will readily accept protons from even weak acids
Endothermic
a term that describes a chemical reaction in which there is a net absorption of energy
Exothermic
a term that describes a chemical reaction in which there is a net release of energy
true of a weak acid?
a weak acid will react with a strong base
What gives vinegar its characteristic smell?
acetic acid
statospheric ozone is important because it
blocks UV light
the breaking and forming of chemical bonds involve
changes in energy
What catalyst facilitates the transformation of oxygen to ozone?
chlorine
What is a way to slow down a chemical reaction?
cool it down
Is it possible for a reaction to occur without a catalyst?
depends on the reaction
Over time, energy tends to become more
dilute
What do you get when you reverse an exothermic reaction?
endothermic reaction
Does the addition of rubbing alcohol to water absorb or release energy?
energy is released
What is a biological catalyst called?
enzyme
increasing reaction rate
increase concentration, adding a catalyst, increase temp.
What happens to the rate of a reaction when the concentration of the reactants is increased?
increases
According to the first law of thermodynamics, energy
is conserved
main characteristic of a strong base?
it is completely dissociated in water
What must reactant molecules have in order to transform into products?
kinetic energy
Moist air is
less dense than dry air.
a catalyst speeds up a chemical reaction by
lowering the energy of activation
is a neutralization reaction best described as a physical or chemical change?
new chemicals are formed during a neutralization reaction, meaning the reaction is a chemical change
If you have two samples that have the same mass but are composed of different elements, then
one sample will have more atoms than the other
OILRIG
oxidation is loss, reduction is gain of electrons
What molecule gives rise to the classic _electrical_ smell?
ozone
Is the addition of rubbing alcohol to water an example of a physical or chemical change?
physical
In order for two molecules to react with each other they must
physically come together
What is always formed from the reaction of an acid and a base?
salt
Entropy is related to the
second law of thermodynamics.
a catalyst is typically used to
speed up a reaction
In a chemical reaction, the release of energy is indicated by the
the (-) sign.
Why doesn_t all the nitrogen and oxygen in our atmosphere react to form nitrogen monoxide?
the atmosphere is too cold
how is Avogadros number related to the numbers on the periodic table?
the atomic mass listed is the mass of Avogadros numbers worth of atoms
The first step of most chemical reactions involves
the breaking of chemical bonds
Which is cleaner: the combustion of gasoline or the combustion of propane?
the combustion of propane is cleaner
true statement regarding the energies of the bonds that break and form in an endothermic reaction?
the energy required to break the necessary bonds is greater than the energy released when the new bonds form
Which molecules in a sample of a reactant molecules are going to be the first ones to react?
the fastest molecules
Add a hydrogen ion to water and you form
the hydronium ion.
Remove a hydrogen ion from water and you form
the hydroxide ion.
The molar mass of any substance is defined as
the mass of one mole of a substance
molar mass
the mass of one mole of a substance
what best describes what happens when an acid such as Hal is mixed with water?
the proton chemically bonded to the chlorine is transferred to a water molecule and forms a chloride ion and hydronium ion
how does a decrease in the temperature of a chemical reaction affect the reaction rate?
the reaction rate decreases
how does a decrease in the reactant concentration affect the reaction rate of a chemical reaction?
the reaction rate decreases. distance between molecules is inversely proportional to concentration therefor at a higher concentration molecules are closer together and collide with each other with higher frequency leading to higher reaction rates
formula mass
the sum of the average atomic masses of the elements in a chemical formula
a central reason for any physical or chemical change is
the tendency of energy to disperse
Why can_t Kai use his catalytic powers on himself?
then he would be one of the reactants