Exam 2 Flashcards
In a chemical equation, what is the term for the starting material?
Reactants
In a chemical equation, what is the term for the ending material?
Products
Which law tells us that chemical equations must be balanced before and after a reaction?
The Law of Conservation of Mass
one mole is equal to what?
6.022 * 10^23
In order to go from moles to moles, what is one important factor we need?
We need to have the molar ratio (coefficients from balanced equation)
To go from Moles to Atoms we use
Avogadros Number
To go from Moles to grams we use
Molar Mass
To go from Moles to Moles we use
Coefficients from balanced reactions
What is an empirical formula?
An empirical formula is the simplified formula of a compound
What is a molecular formula?
A molecular formula is the true formula of a compound
If a formula can be reduced by the same factor, is it empirical or molecular?
Molecular
How do we determine empirical formulas?
If we are given that percent, simply turn it into grams (no conversion) and then convert it from grams to moles. In order to get a ratio, we must divide all of the moles by the smallest mole. Now that we have all of the values, plug them as subscripts to their corresponding compound.
How do we determine molecular formulas?
To find molecular formula, first find the empirical formula. After you have it, find the molar mass of the compound, Since we are given a molar mass (in the problem), if it does not match your calculation, divide the molar mass that you were given by the molar mass you calculated. Whatever value you get tells us our formula is off by that factor.
What is the oxidation state of free elements?
0
In compounds, group 1 elements have an oxidation state of
1
In compounds, fluorine has an oxidation states of
-1
Group 2 metals have an oxidation state of
+2
Group 3 ions have an oxidation state of
+3
In compounds, hydrogen has an oxidation state of
+1
In compounds, oxygen has an oxidation state of
-2
How do we identify oxidation?
Oxidation is the loss of electrons
How do we identify reduction
Reduction is the gain of electrons
t/f oxidation and reduction take place simultaneously
true
If an element is oxidized, what is its agent?
Reducing agent
If an element is reduced, what is its agent?
oxidizing agent
In the ideal gas law, what are the units?
atm, Kelvin, Liters, moles
What is the constant of the ideal gas law?
R
What is r equal to?
0.0821
What is standard temperature and pressure?
273 K and 1 atm
If we have one mole of any gas at STP, what is the volume?
22.4 Liters
Which law tells us the relationship between volume and pressure? What is the relationship?
Boyles law, As volume decreases, pressure increase
Which law tells us the relationship between volume and temperature? What is the relationship?
Charles law, As volume increases, temperature increases
Which law tells us the relationship between pressure and temperature? What is the relationship?
Gay Lussac law, As pressure increases, temperature increases
Which law tells us the relationship between moles and volume? What is the relationship
Avogadro’s law, As moles increase, volume increases
What is the equation for Boyles law?
P1V1=P2V2
What is the equation for Charles Law?
V1/T1 = V2/T2
What is the equation for Gay Lussac’s Law?
P1/T1 = P2/T2
What is the equation for Avogadro’s Law?
V1/n1 = V2/n2
What is the formula for pressure?
P= Force/Area
What is the standard pressure?
1 atm or 760 torr
How do we go from atm to torr?
multiply by 760
How do we go from torr to atm?
divide by 760
What does Dalton’s Law of Partial Pressure tell us?
The total pressure is equal to the sum of the individual pressures
t/f gases usually exist as individual molecules/atoms
false, they exist in mixtures
What is it called when we go from a solid to a liquid?
melting
What is it called when we go from a liquid to a solid?
freezing
What is it called when we go from a Liquid to gas
Vaporization
What is it called when we go from a gas to a liquid?
condensation
What is it called when we go from a gas to a solid?
sublimination
What is it called when we go from a solid to a gas?
deposition
why is solid water less dense than liquid water?
It is less dense because when water freezes, the molecules form a crystalline structure that is held together by h bonding. Since we know water is a polar molecule, the positive of hydrogen attracts to the negative of oxygen between other h2o molecules.
A polar molecule has a/an _______ distribution of electrons
unequal
Describe solids in terms of movement, structure, shape, volume and compressibility
Solids only vibrate because they have a tight structure. They have a fixed volume and shape and are incompressible (except for ice)
Describe liquids in terms of movement, structure, shape, volume and compressibility
Liquids have a bit more movement, fixed volume and is incompressible
Describe gas in terms of movement, structure, shape, volume and compressibility
Gases have the most kinetic movement, it does not have a fixed volume or shape and it is compressible
Are changes of state physical or chemical changes?
physical
Rank the attraction forces for gas, liquids and solids
Solids > Liquids > Gas
What is the difference between intermolecular forces and covalent/ionic bonds?
Intermolecular forces are the bonds between 2 molecules while covalent bonds are the bonds between 2 atoms in a molecule
Which forces are weaker? Intermolecular or covalent?
Intermolecular forces
What are the three main types of IMF?
- London Dispersion
- Dipole-Dipole
- Hydrogen Bonding
Which IMF is present in all molecules?
London Dispersion
Which IMF ispresent in polar molecules?
Dipole Dipole
How does Hydrogen bonding become relevant?
This happens when Hydrogen bonds to really electronegative elements such as F, O or N
what is the order of the IMF forces? Strongest to weakest
Hbond> Dipole Dipole> London Dispersion>
What is the relationship between IMF and phase change?
The stronger the IMF, the higher the boiling/melting point (more energy needed)
What is the relationship between IMF and surface tension?
The stronger the IMF, the higher the surface tension
What is the relationship between IMF and vapor pressure?
The stronger the IMF, the lower the vapor pressure
Strong IMF produce low amounts of evaporation (molecules are attracted)
What is vapor?
When a substance is present as both a gas and a liquid
What is the difference between vaporization and evaporation?
In evaporation, particles can completely escape. In vaporization, we have an equilibrium where particles are equally converting back and forth between a gas and a liquid.
What is boiling?
It is a type of vaporization where evaporation takes place in the whole container rather than on the surface
When does boiling occur?
When vapor pressure is equal to atmospheric pressure
What process occurs when vapor pressure is less than atmospheric pressure?
Evaporation
t/f boiling can occur at any temperature
true, as long as the outside pressure if the same as the vapor pressure
What is the relationship between low pressure and boiling point?
At low pressure, it takes more energy to reach a boiling point which also means it takes longer
What is the relationship between high pressure and boiling point?
At high pressure, it takes less energy to reach a boiling point which means itis faster
What atmospheric pressure does the normal boiling point refer to?
760 torr, 1 atm
What are the diatomic molecules?
hydrogen, nitrogen, oxygen, fluorine, chlorine, iodine, bromine.
What should we remember when converting grams to atoms?
if you want tofind atoms of a molecule, multiply by however many atoms there are. If you want to find one specific element, multiply by however many there is.
How is oxidation determined in a compound?
In an equation, if a element’s oxidation number was higher, it lost electrons because the oxidation state should be positive (more protons)
How is reduction determined?
Reduction is the gain of electrons so if an element’s oxidation number went from positive to negative or (lowered), it gained electrons because it has a negative charge
How is the agent (oxidation and reducing) stated?
Although we are working with individual elements, the agent will be the compound in the reactant side. Lets say Hydrogen was oxidized in H2O. Hydrogen would be oxidized but H2O would be the reducing agent.
If a polyatomic ion has a charge, what is the oxidation number?
Whatever the charge is.. make sure you memorized
How do you go from Farenheit to Celsius?
First subtract by 32 and then multiply by 5/9.
