Chemistry Final Flashcards
Dilution
Dilution Equation
(Mi)(Vi)=(Mf)(Vf) Mi= Initial molarity Mf= Final Molarity Vi= Initial Volume Vf= Final volume
Molarity
Moles of solute per liter of solution
Concentration = amount of stuff per unit of area or volume
Molarity = moles of solute / liters of solution = M notation
The “mole”, grams->mole conversions, etc…
Use the molecular weight to determine the Moles of a compound, add each mass of each element, pay attention to subscripts.
Avogadro’s Number
6.022x10^23
number of units in one mole of any substance (defined as its molecular weight in grams),
Percent Compostion
(Mass of X/ Mass of Whole) * 100
Molecular weight
Empirical Formula
Tells us:
- what elements are present in the compound
- the ratio of the elements in the compound (but not the exact number)
Steps to Calculate Empirical Formula
p159-163
0) Assume 100g
1) Calculate the Moles
2) Calculate the Ratio
3) Scale the Ratio (if needed)
Molarity
Brackets indicate molarity of a substance [CaSO4] = 1.00 M
Dilution: MiVi = MfVf ,
where i is the initial amount and f is the final amount
Steps to solving molarity problems:
- Find the givens in the problem, and what we need to find
- Take what is given and put it over one
- Use stoichiometry to put all numbers with correct units: ex. Ml / 1000 = L
- Solve for the unknown using the molarity formula M = moles / liters
- Convert the answer into a different form if the problem calls for grams instead of moles or for milliliters instead of liters using stoichiometry
- May need to multiply by the number of moles of an ion in the formula to get an answer respective to the number of units for that ion in the formula
Use mole: mole ratio, ex. If need Fe ions in Fe2O3 and given the mass of Fe2O3, use the ratio 2 mol Fe: 1 mol Fe2O3
Steps to writing Dilution Problems
- Write the known values and what you need to find according to the problem
- Plug the values into the equation and calculate the final answer
- May need to multiply by the number of moles of an ion in the formula to get an answer respective to the number of units for that ion in the formula
Concentration and Molarity:
Concentration is how much stuff per unit area or volume, while molarity is how many moles per liter of solution.
Dissociation
the process when an ionic compound dissolves in water, its ions separate and become surrounded by water molecules.
Electrolytes
Free Ions in solution, conduct electricity
Solute
The substance being dissolved
Solvent
The substance doing the dissolving
Strong electrolyte
completely converted to ions when it forms an aqueous solution
Stoichiometry Train
On our Stoichiometry train we now have to places in which we can get on. We can now either start at the grams station or the volume station.
If we get on at the grams station and are trying to get to the moles station we have to use the molar mass ticket. You determine molar mass by the periodic table.
Stoichiometry Train
If we started at the volume station instead of the grams station then we get to the moles station by molarity. We figured out how to find molarity above.
Now we are at the moles station. To get to the mole:mole station we look at the balanced equation.
Stoichiometry Train
We have now arrived at the mole:mole station and are on our way to the moles station. To get to the moles station we once again use the balanced equation ticket.
Now that we are at the moles station we have to look at the original problem and determine if we need to go to the grams station or the volume station to get off.
Stoichiometry Train
If you need to get off at the grams station you need to use the molar mass ticket. Once again, you get the molar mass from the periodic table.
If you need to get off at the volume station instead then you need the molarity ticket which was previously discussed.
Limiting Reagent
1) Ride the train for each reagent
2) Compare the theoretical/max yield determined for each reagent
3) Identify the limiting reagent and correesponding max/theoretical yield
Scientific Notation
Left (+) #
Right (-) # to the power
T= Tera G= Giga M=Mega K= Kilo D=Deca
12 9 6 3 1
d=deci c=centi m= milli Micro n=nano p= pico
- 1
- 2
- 3
- 6
- 9
- 12
Density = mass/volume
the amount of matter present in a given volume of a substance
K = C + 273.15
F = C × 1.8 + 32
C = ( F - 32) / 1.8
F= C*1.8+32