REVIEW CLASS, JUNE 16 AND JUNE 17 2007
#2) Aluminum is
therefore Z = 13 and A = 27.
27
Al
Electrons =
Protons in a
neutral atom.
13
There is no
charge written,
it is neutral.
ANS-2)The number
of protons is the
nuclear charge (+13)
and the number of
electrons (neutral
atom only).
#4) ANS-2: Both the proton and neutron have a mass of 1 AMU (1/12 the mass of
C-12)
#5) Potassium (K) is in the same GROUP and therefore has the same valence shell
electron configuration.
#7) Li has the highest melting point (table “s”).
#6) % Composition = part/molar mass x 100
% composition of Al = 2 Al/ Al2(SO4)3 = 2(26.98)/342 x 100 = 15.8%
#8) Mg, Ca and Ba are in the same group, ANS=2
#9) Fe(II)S iron sulfide (TABLE “F” S2- IS SULFIDE). NOTE THET THE NEGATIVE
ION OF A NON-METAL ENDS IN “IDE”, SULFER (S) IS sulfiIDE. THE ROMAN
NUMERAL IS THE POSITIVE CHARGE OF THE METAL Fe.
Fe2+ S2-
Fe2S2
FeS, ans choice 1)
#11) Covalent bonds are in molecular substances only.ANS-1
#12) NaCl(aq) is a homogenous mixture because the solution of salt in water is
one phase, (aq).
#13) A DOUBLE BOND IS 4 ELECTRONS.
#14) CH4 IS TETRAHEDRAL (4-BONDS), SYMETRICAL AND NOT POLAR. NOTE
THE BONDS ARE POLAR, BUT THE MOLECULE IS SYMETRICAL. ANS-3
#15) As you remove electrons, the e- cloud gets smaller and a proton is unpaired.
The atom gets smaller and positive – ANS-2.
#16) Heat always flows from more (hotter) to less (colder). The 50o choice is cooler
then the 60o sample and heat flows into it, ANS-1. Also the cooler object has the
least average kinetic energy.
#17) Real gasses are most ideal at high temp (break attractions and causes more
random motion and collisions) and low P (spreads the particles). ANS 3– 750K and
20kPa – highest T and lowest P.
#18) At similar T, P equal volumes of any gasses are equimolar, ANS-3
#19) 4L of CO2
#20) ETHYNE IS AN ALKYNE AND HAS A TRIPLE BOND, SIX SHARED
ELECTRONS.
#21)ANS-4 Both have the molecular formula C2H6O.
#22)ANS-4 2-pentene has a double bond (CnH2n)
#23)ANS-1 Oxidation causes the oxidation number to INCREASE from reactant to
product. –1 to +2 is an increase of 3 (3 mol of e- are lost).
#24) The rate of a reaction increases with concentration (molarity for solutions)
and temperature (T). ANS – 4 has the highest molarity and Temperature.
#25) Conductors are soluble (aq) salts from table “F”, acids or bases. KOH is a
base (table “L”, Or a group one or two hydroxide) , the higher molarity gives the
most ions upon dissociation KOH  K+ + OH-. ANS-4, highest molarity base.
NOTE CH3OH is an alcohol which is NOT an electrolyte (even though it looks like a
base, it is not a base).
#26) A H+ ion may also be written as a) H2O2 b)H2O c) OH- d) H3O+ ,
ANS-d), by definition H3O+ is equivalent to H+
#27) One acid base theory states that an acid is: a) an e- donor b) a neutron donor
c) ANS- an H+ donor d) an OH- donor
#28)Which Isotope will decay spontaneously and emit a particle with a charge of
+2? A) Fe-53 b) Cs-137 c) Au-198 d) Fr-220
Radiation of +2 charge is an alpha particle, and table “N” lists natural decay. Find
the alpha emitter on table n from the choices. The answer is Fr-220 d), the only
alpha emitter – Cs-137, Fe-53 and Au-198 are beta
#29) Co-60 undergoes beta decay, this type of radiation is a) natural transmutation
b) artificial transmutation c) fusion d) fission
The decay of Co-60 is on table “n”, it is natural transmutation.
#30)Given the reaction, compared to the total charge of the reactants the charge
of the total products is;
2Al + 3Cu2+  2 Al3+ + 3 Cu
2(0) + 3(2+) = 2(3+) + 3(0)
6+ = 6+ the same
#31) % Composition = part/molar mass x 100
FIND %Br in
AlBr3
% composition of Br = 3 Br/ AlBr3 = 3(79.9)/256.7 x 100 = 93% ANS-4
#32) Al+3 has lost 3 electrons (each + charge represents a lost electron).
The neutral atom has 13 protons, thus there are 13 electrons in the neutral
atom. If three e- were lost 10, are remaining. ANS-4
#33 The excited state must have the same # of electrons as the neutral
atom, however one or more must be at a higher energy level (outermost
shell) that the ground state of the periodic table ( for Al it is 2-8-3), 13
electrons.The ans is 1) 2-7-4 (13 e-), one electron promoted from shell 2 to
shell 3.
#34) non-metals are brittle non conductors. This cannot be METALLIC as
metals are soft, and metallic solids conduct. Look for an element on the
non-metal side of the table, it is S, 16 protons.
#35)X in XBr3 can best be solved by oxidation number rules. The sum of
the oxidation numbers = 0 for this neutral substance.
XBr (remember, halogens are usually 1- in binary compounds)
X + 3(-1) = 0, X=3+, group 13: ANS-3
#36) a sample contains 65.4 g of Zn, 12 g of C, and 48.0 g of O what is the
mole ratio?
Mass/Atomic mass
element
Ans-3 1:1:3
Zn
C
O
Raw mole
ratio
65.4/65.4 = 1
12.0/12.0 = 1
48.0/16.0 = 3
Divide by
smallest
Simple
ratio
/1
/1
/1
1
1
3
YOU DID NOT NEED TO DIVIDE BY THE
SMALLEST OR REDUCE IN THIS PROBLEM,
THE RAW RATIO WAS THE MOST REDUCED
WHOLE NUMBERS ALREADY.
#37) Which process would best separation two liquids with different
molecular polarities? 1) filtration 2)fermentation 3) distillation
4)conductivity
Distillation separates based on boiling point, which differs with polarity
(more polar boils at higher temp).
#38) For the balanced equation
AgNO3(aq) + NaCl(aq)  NaNO3(aq) + AgCl(S)
AB + CD  CB + AD
A double replacement - must form a solid .
#39) At 40oC about 63 g of KNO3
Will dissolve in 100g of water. If you
already have 35g, you can dissolve
About 28g more. Closest ANS-1(29)
(40oC,63g)
#40) Bottle 1 shows particles spread out (as opposed to clustered)
FILLING the container VOLUME AND ASSUMING THE SHAPE, must be a
gas.
#41)How many moles of NaCl are needed to make 3.0L of 2.0 M NaCl
solution.
M = mol/L
2.0M = mol/3.0 L; 6 mol ANS-3
#42) Lewis valence dot for sulfide is:
[
S
[
RED ELECTRONS
WERE GAINED
2-
#43 ANS-4 Add enough water to make the SOLUTION 1L total, including
the solvent which displaces a small amount of water.
#44) there is NO change of T in a phase change, in this problem:
q = mass x heat of fusion, q = 5.00 x 334J/g = 1670 J released OR –1670 J
because freezing is exothermic.
#45) Choice 1,2,3 do not change the formula – all are physical – 1) is
evaporation- a phase change, 2) is melting, 3) is simple crushing. ANS-4
because it reacted.
#46) the Gas phase always has the highest entropy, followed by liquid and
the solid has least. Entropy also increases with Temp. Ans-4, a gas.
#47) Addition does not produce a mineral acid (HCl), addition can add 2 Cl
atoms and substitution cannot. This reaction is addition, With addition
you need a double bond, choose the alkene or alkyne. ANS-2 – is
unsaturated – can undergo addition (CnH2n-2).
#48) In the reaction 4 Fe + 3 O2  2 X,
There must be 4 Fe on the right, the answer must be Fe2O3. (Ans-2)
#49)FACT 1- Both are acids (table K)
FACT 2- Acids turn blue litmus to red. ANS 1).
#50) From U-238 to U-234 is alpha ( mass # decreased by 4, atomic # by 2
indicates alpha.) From Th-234 to Pa-234 the atomic number increased by 1
indicating beta decay. Pa-234 to U-234 is also beta for the same reason.
ANS -4