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CHEM LAB FINAL EXAM QUESTIONS
AND ANSWERS LATEST UPDATE
GRADED A+ 2023/2024

Which statement is true about a chemical reaction at equilibrium? - ANSWER- The
forward reaction rate is equal to the reverse reaction rate
...
If you create an equilibrium mixture from
Fe3+ and SCN− ions, adding Cl− ions will _____________________ because
______________________________
...
- ANSWER- endothermic

Heat is a product in the reaction - ANSWER- exothermic

When any reversible reaction is at equilibrium, what conditions are necessarily
true? - ANSWER- -Reactants and products are both present in the reaction mixture
...


-The amounts of reactants and products has stopped changing
...
Heat applied to an endothermic
reaction will shift the reaction towards _______________
...
- ANSWER- -titrant volume

-pH

If a 1
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40 mL of 0
...
36 M
1
...
258 M x (32
...
0083592
2
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0083592x1000

If 0
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50 mL of 0
...
find moles of base:
(
...
5)/1000=
...
find molar mass of acid:

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0011475=65

The pKa of an acid can be determined through _____________ with a strong base
...
The pKa of the acid is equal to the pH at the
___________________
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- ANSWER- Cl-=HCl

I-=HI
SO42-=Bisulfate ion
F-=HF
OH-=Water

Given the pKa of each acid, determine whether it is strong or weak
...
1
weak

acetic acid, pKa=4
...
Rinse the pH meter with __________________
and gently pat dry
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- ANSWER- -storage solution

-deionized water
-stabilizes

Would the pH at the equivalence point be acidic, basic, or neutral for each given
titration? - ANSWER- HClO4 with
Ba(OH)
neutral

HCl with NH3
acidic

CH3CH2OH with Sr(OH)2
basic

The equivalence point of any acid-base titration can be determined visually from a
titration curve by finding the place where - ANSWER- the curve has the steepest
slope
...


If the pH at the half-titration point of a weak acid is 4
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3E-5

10^-4
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0 mL sample of a saturated
Ca(OH)2 solution is titrated with 0
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9 mL of titrant are dispensed
...
019

(
...
9)/1000
HCl is 2x the moles of Ca(OH)2
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0 mL sample of a saturated
Ca(OH)2 solution is titrated with 0
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5 mL of titrant are dispensed
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034

Begin by finding the number of moles of the titrant,
HCl
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(0
...
5)/1000

The molar solubility of
Ca(OH)2 was experimentally determined to be 0
...
Based on this value, what
is the Ksp of Ca(OH)2? - ANSWER- 0
...
022)(2*0
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This is
because the NaF solution contains __________________ that __________ further
dissociation of PbF2 into Pb2+ and F-
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Any further addition of salt will remain undissolved
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- ANSWER- Solubility product
constant

A decrease in the solubility of an ionic compound as a result of the addition of a
common ion
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ANSWER- Molar solubility
The mass of a salt in grams that will dissolve in 100 mL of water
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25 x 10-5 M Ag+
ions
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- ANSWER- 1
...
25E-5M)(1
...
60 mL
of 0
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Based on this titration, what is the Ksp of AgOH?
- ANSWER- 2
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00260 L x 0
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54E-5/
...
41E-4
(1
...
00E-8

Consider the equilibrium describing the endothermic dissolution of a solid in
water
...

Suppose you add 0
...
0 mL of water
...
0159 M and the concentration of Cl−(aq)) is
0
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What is the value of the equilibrium constant, Kc, for the dissolution of
PbCl2? - ANSWER- 1
...
0159 M][0
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ANSWER- -A: 0
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At the beginning of the titration, you read the base titrant volume as 2
...

After running the titration and reaching the endpoint, you read the base titrant
volume as 18
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What volume, in mL, of base was required for the titration? - ANSWER- 16
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- ANSWER- -Close to
the calculated endpoint of a titration: Partially open

-Filling the buret with titrant: completely closed

-at the beginning of aa titration: completely open

-Conditioning the buret with titrant: completely closed

A reagent added to the analyte solution that changes color when the reaction is
complete - ANSWER- Indicator

Solution of an unknown concentration that has another solution slowly added to it ANSWER- Analyte

Glassware that allows a solution to be precisely and slowly added to another
solution - ANSWER- Buret

Solution of known concentration that is slowly added to a solution of unknown
concentration - ANSWER- Titrant

Process of slowly adding a solution to react with another solution and determine
the concentration of one of the solutions based on the reaction between them ANSWER- Titration

When the required amount of one solution has been added to the second solution to
complete the reaction - ANSWER- Endpoint
How should you prepare a buret for titration before loading it with titrant? ANSWER- Condition the buret with titrant solution

Suppose you analyze a 33
...
08 g
of sodium hypochlorite present
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14

2
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9 x 100%

Suppose in an experiment to determine the amount of sodium hypochlorite in
bleach,
0
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63 mL1
...
00644

mols thiosulfate= moles KIO3x6
=9
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01463) =
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45 mL sample of 0
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The endpoint was observed to occur at 14
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How many moles of
KIO3 were titrated? - ANSWER-
...
0100molx
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0000443 mol KIO3 were titrated with an unknown solution of Na2S2O3 and the
endpoint was reached after 17
...


How many moles of
Na2S2O3 did this require? - ANSWER-
...
0000443x6

When determining the amount of an oxidant present by titration, you can use
iodine and starch as an indicator
...
When starch
and iodine are both present, the solution is ____________
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When the
iodine has completely reacted at the endpoint of the titration, the solution should
become __________
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- ANSWER- -water
-carbon dioxide
Identify the safety equipment designed to deal with each emergency listed
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29 g of a fuel causes the water in a calorimeter to increase by 11
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If
the calorimeter has a heat capacity of 3
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8

-3
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2=-34
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608/1
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8

Suppose you need to calibrate a calorimeter
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736 g of a fuel with an enthalpy of combustion of −48
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If the temperature
of water in the calorimeter increases by 14
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47

-48
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736g=-35
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84/14
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47=2
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The calorimeter is __________ to prevent transfer of heat to outside the device
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3 kJ/g and fuel B has an energy density of −35
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The fuel with greater energy density is_________ because you need to burn
_______ of Fuel A than Fuel B to produce the same amount of heat
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-Inform the instructor and everyone working around the area about the spill
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- ANSWER- -The burner should be lit for 20
seconds after any change before proceeding
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-The burner wick should be about a few millimeters above the metal stem
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C7H16+ 11O2-----> 7CO2+ 8H2O
Using the given enthalpies of formation, ΔH∘f for each species, determine the
enthalpy of combustion of heptane
...

EoCell= 1
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120 M solution of
Zn2+(aq) and 0
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6 K? - ANSWER- 1
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1032V-(8
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6K)/(2x95485)xln(2
...
1550)

Consider the diagram of the electrochemical cell
...
The purpose of the
Na2SO4 is to ____________________
...
In the salt bridge, _________ move toward the anode and
_________ move toward the cathode
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- ANSWER- Pressure of
1 atm
solution concentrations of 1 M
Temperature of 298 K

what is the standard cell potential - ANSWER- 1
...
36-(-
...
314 J/molK
temperature in K
number of electrons
Faraday constant
reaction quotient

The electrode where oxidation occurs

An electrochemical cell powered by a spontaneous redox reaction

An electrochemical cell that takes in energy to carry out a nonspontaneous redox
reaction

The electrode where reduction occurs

A chemical equation showing either oxidation or reduction - ANSWER- anode

galvanic cell

electrolytic cell

cathode

half-reaction

Identify the oxidation half reaction of Zn(s)
...
- ANSWER2Fe(s) + 3Cl2(g)→ 2Fe3+(aq) + 6Cl-(aq)

Al---->Al3+
Cu2+----> Cu+
2F- ----> F2 - ANSWER- oxidation, 3, product
reduction, 1, reactant
oxidation, 2, product

suppose you mix an unknown solid with oil and the added solid dissolves into the
oil
...
What is most likely true
about the unknown liquid? - ANSWER- It is a polar liquid

Determine whether the structure is correct and justify your decision - ANSWERThis solution is incorrect because the octet rule in not fulfilled
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o-c-o

what characteristics of molecule determine whether or not it is polar? - ANSWERThe arrangement of bonds around the molecule
...


Determine whether the structure is correct and justify your decision
...
o has 2
lone pairs and 2 bonded pairs
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ANSWER- c+o2=co2 (combustion)
CO2+4H2=CH4+2H20 (not combustion)
2NO+O2=2NO2 (combustion)
2N2O5=4NO2+O2 (not combustion)
2C2H6+7O2=4CO2+6H20 (combustion)

Determine each type of reaction - ANSWER2C2H2(G)+5O2(G)=4CO2(G)+2H2O(l): COMBUSTION

Determine each type of reaction - ANSWERCACL2(AQ)+NA2CO3(AQ)=2NACL(AQ)+CACO3(S): DOUBLE
REPLACEMENT
Determine each type of reaction - ANSWER2FE(S)+6HCL(AQ)=2FECL3(AQ)+3H2(G): SINGLE REPLACEMENT

Determine each type of reaction - ANSWER- CO(G)+2H2(G)=CH3OH(L) :
COMBINATION

Determine each type of reaction - ANSWER- NH4NO3(S)=N2O(G)+2H2O(L):
DECOMPOSITION
In the context of a balanced chemical equation, a - ANSWER- (subscript) is a
number to the lower right of an element or ion within formula and it applies to
(only the part of the formula it follows)
...
Only (coefficients) should
be added or changed when balancing chemical equations
...
At least
one reactant
...


Determine what type of reaction each unbalanced chemical equation represents
...
ANSWER- AgNO3+NaCl=NaNO3+AgCl (double replacement)

Determine what type of reaction each unbalanced chemical equation represents
...
ANSWER- CaCL2+Na3PO4=Ca3(PO4)2+NaCl (double replacement)

predict the products of hydrochloric acid reacting with zinc metal
...
6ml of a 0
...
What
mass of NaCL do you need to use to make the solution? - ANSWER- 3
...
30 g/mol
...
8 mL aqueous solution prepared with 78
...
01

Suppose you have 450
...
350 M sodium hydroxide solution
...
158

Determine whether each of the given characteristics refers to electrolytes or nonelectrolytes
...
- ANSWER- do not dissociate in solution- non-electrolytes

Determine whether each of the given characteristics refers to electrolytes or nonelectrolytes
...
- ANSWER- do not conduct electricity- non-electrolytes

Determine whether each of the given characteristics refers to electrolytes or nonelectrolytes
...
- ANSWER- examples incude NaOH and KBr- electrolytes

Determine whether each statement describes a solution of a strong electrolyte,
weak electrolyte, or non-electrolyte
...
- ANSWER- contains a completely
dissociated solute- strong electrolyte

Determine whether each statement describes a solution of a strong electrolyte,
weak electrolyte, or non-electrolyte
...
- ANSWER- contains a complete solutenonelectrolyte

Determine whether each statement describes a solution of a strong electrolyte,
weak electrolyte, or non-electrolyte
...
- ANSWER- contains a partially dissociated
solute- weak electrolyte

Calculate the percent by mass of a solution made from 19 g NaCl (the solute) and
64 g water
...
3 mL47
...
65 M HCl
solution? - ANSWER- 0
...


Use this object to fill the pipet such that the - ANSWER- (meniscus) of the liquid
is even with the volume line
...
- ANSWER-

When sodium chloride,
NaCl
, dissolves in water, the solution contains - ANSWER- (sodium ions and chloride
ions) in addition to the water solvent
...
- ANSWER- Used for applications in which great accuracy is
needed (volumetric)

Determine whether each of the properties d

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