Princeton Ch 3 - Chemistry Fundamentals Flashcards
1mL = 1 ___?
1 mL = 1 cm3 = 1 cc –> 1 cubic centimeter
What does Angstrom equal to?
10^-10 m. The Angstrom is convenient because atomic radii and bond lengths are typically around 1-3 A.
Define density.
Mass per volume of a substance. Typically written as g/cm3.
How does one convert g/cm3 –> kg/m3?
Multiply by 1000. For example, the density of water is
1 g/cm, which could be written as 1000 kg/m3.
How do you convert kg/m3 –> g/cm3?
Divide by 1000.
Define molecular formula.
A compound molecular formula gives the identities and numbers of the atoms in the molecule. H2O is a molecular formula.
Define empirical formula.
The smallest whole numbers that give the same ratio of atoms. C6H12O6 –> CH2O
See phone for polyatomic ions (or molecular ions) that you should be familiar with.
See phone. Polyatomic ions is a charged chemical species (ion) composed of two or more atoms covalently bonded or of a metal complex that can be considered to be acting as a single unit.
Formula weight = atomic mass unit. What is an atomic mass unit?
One atomic mass unit is equal to exactly 1/12 the mass of an atom of carbon 12. The periodic table lists the atomic mass of each element, which is actually a weighted average of the atomic masses of all its naturally occuring forms (isotopes).
How do we find the number of moles in a sample that contains 70% Fe and 30% Oxygen? How do we find the empirical formula from this?
Choose 100g. #moles Fe = 70g/(55.8g/mol) –> 5/4
#moles O = 30/(16g/mol) = 15/8;
Because the empirical formula involves the ratio of # of atoms, the ratio of Fe: O is (5/4)/(15/8) = (58)/(415) = 2/3
Fe2O3
Define molarity.
Molarity (M) = #moles of solute/#liters of solution; [mol/L}
Define mole fraction.
The fraction of moles of a given substance relative to the total moles in a solution.
mole fraction of S = Xs = (#moles of substance S)/ (total 3 of moles in solution)
A chemical equation is _____ if, for every element represented, the # of atoms on the left side is equal to the # of atoms on the right side.
Balanced. This illustrates the Law of Conservation of Mass/Matter, which says the amount of matter (and thus mass) does not change in a chemical reaction.
In the balanced equation 2Al + 6HCL –> 2AlCl3 + 3H2; how many moles of reach with one another?
This equation means that 2 moles of Al react with 6 moles of HCl to form 2 moles of AlCl3 and 3 moles of H2.
See phone for balancing equations methods
Do it, fool.
Describe what limiting reagent is.
The reactant we run out of first.
Describe what an oxidation state is.
An atom’s oxidation state is mean to indicate how the atom’s ownership of its valence e- changes when it forms a compound. When Na forms NaCl with Cl, the Na atom will transfer its valence e- to the Cl atom. So the Na’s ownership has changed. We use +1 in this case. +1 = one less e-
The oxidation state of any element in its standard state is____.
0.
The sum of the oxidation states of the atoms in a neutral molecule must always be ___.
0.
The sum of the oxidation states of the atoms in in a ion must always equal to _____.
The ion’s charge.
Group 1 metals have a ____ oxidation state. Group 2 metals have a ____ oxidation state .
Group 1 metals have +1 oxidation state. Group 2 metals have +2 oxidation state.
Hydrogen has a ____ oxidation state when bonded to something more EN than C and ____ when bonded on an atom less EN than C, and ____ when bonded to carbon.
+1, -1, 0.
Oxygen has a _____ oxidation state.
-2. The rest of the atoms in the oxygen family also have a -2 oxidation state.
Halogens have a ____ oxidation state.
-1
Comment on the oxidation states of transition metals.
Like many other elements, transition metals can assume different oxidation states, depending on the compound they’re in.
There are rules to assigning oxidation states. Name 1-4. See phone.
1) OS of any element in standard state is 0.
2) The sum of OS of the atoms in a neutral atom must always be 0; for ions, the sum must equal the charge. 3) Group 1 metals = +1 and group 2 metals = +2.
4) Fluorine has a -1 oxidation state.
There are rules to assigning oxidation states. Name 5-7.
5) H has +1 when bonded to something more EN than C. H has -1 when bonded to something less EN than C. H has a 0 when bonded to C.
6) Oxygen has a -2 oxidation state.
7) The rest of the halogens have -1; the atoms of the oxygen family have a -2 oxidation state.
