General Chemistry Flashcards
Ice melting is an example of an ___ reaction.
a) endothermic
b) exothermic
endothermic
the heat is being taken in
A lit match is an example of an ___ reaction.
a) endothermic
b) exothermic
exothermic
heat is being released
Define: Heat Capacity
The quantity of energy required to change the temperature of a substance by 1ºc.
True or false: you loose an electron in reduction.
False.
You loose an electron in oxidation. You gain an electron in reduction
(I know, weird…)
What is the oxidation number of O2?
It is always 0
because it is a single type of element
What is the oxidation number of the Mn in KMnO4?
Hint: K is +1 and O is -2 and it is 0 overall
Mn=+7
+1+Mn+4(-2)=0
-7+Mn=0
Mn=+7
An excess of K2SO4 was added to a liter of Roman tap water. 0.315 g of PbSO4 solid precipitate was formed. How many moles of Pb (lead) were in the liter of tap water?
0.00103 moles of Pb
Pb+K2SO4–>PbSO4
0.315 g PbSo4(1 mol PbSo4 / 303.262 g PbSO4)= 0.00103 moles of PbSO4
We know (from the equation) that there is a 1:1 ratio between the Pb and the PbSO4, so they must have the same number of moles.
Define: Paramagnetic
attracted to a magnetic field because of unpaired electrons
Define: Diamagnetic
not attracted to a magnetic field because of paired electrons
Longer waves, ____ energy.
Longer waves, less energy.
How much energy is needed to bring a 3.10 g penny (minted in 1856, a year before pennies stopped being 100% pure copper) from -8ºc to 37ºc?
Hint: Cs of Cu= 0.385 J/g•ºc
53.7 J
q=m•Cs•Δt
3.10g(0.385 J/g•ºc)45ºc=53.7 J
What is Ionization Energy?
The Ionization Energy (IE) of an atom or ion is the amount of energy required to remove an electron from said atom or ion (while it is in a gaseous state).
What is Electron Affinity?
Electron Affinity (EA) is the energy change associated with the gaining of an electron by the atom in the gaseous state.
What are the differences between Covalent, Ionic, and Metallic Bonds?
Covalent: electrons shared between two nonmetals
Ionic: electrons transferred between metal and nonmetal
Metallic: electrons pooled between metal atoms
What is an activated complex?
The high energy state right before the chemical reaction
