Chemistry 101 Sections 501-512 Worksheet With Answer Key - Texas A And M University, 2001

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NAME: _________________________________
Form 1 (blue)
September 17, 2001
QUIZ #1
CHEM 101
1) Fill in the blanks to balance the following equations:
+ ____C ! __2_FeCl
__2_FeTiO
+ _2__Cl
+ __2_TiO
+ ____CO
3
2
2
2
2
2) Name the following compounds
a) CaCl
____calcium chloride_______
2
b) CuBr
____copper(II) bromide_____________
2
c) N
F
____dinitrogen tetrafluoride____________
2
4
3) Mandelic acid is an organic acid composed of carbon (63.15%), hydrogen (5.30%), and
oxygen (31.55%) by mass.
a) What is the empirical formula for this compound? Assume 100 g
! ! ! ! 5.258/1.972 = 2.666 = 8/3
C: (63.15 g C) x (1 mol C/12.011 g C) = 5.258 mol C
! ! ! ! 5.26/1.972 = 2.667 = 8/3
H: (5.30 g H) x (1 mol H/1.008 g H) = 5.26 mol H
! ! ! ! 1.972/1.972 = 1.000 = 1
O: (31.55 g O) x (1 mol O/15.999 g O) = 1.972 mol O
O ! ! ! ! need whole numbers so mulitply by 3 ! ! ! ! C
C
H
H
O
8/3
8/3
8
8
3
b) If the molar mass of the compound is 152.14 g/mol what is the molecular formula of the
acid?
Using empirical formula molar mass of C
H
O
= (8 x 12.011 g/mol) + (8 x 1.008 g/mol)
8
8
3
+ (3 x 15.999 g/mol) = 152.15 g/mol
Molar mass/Emprical molar mass = 152.14/152.15 = 0.99993 = 1
Molecular formula is same as empirical formula, C
H
O
8
8
3
4) Ammonia gas can be prepared by the reaction of a metal oxide such as calcium oxide with
ammonium chloride by the reaction shown below.
Cl ! 2NH
CaO + 2NH
+ H
O + CaCl
4
3
2
2
A reaction takes palce between 112 g of CaO and 224 g of NH
Cl and goes to completion.
4
a) What is the limiting reagent (circle one shown to the right):
CaO
NH
Cl
4
SHOW WORK!!
CaO: 112 g CaO x [1 mol/(40.078 g + 15.999 g)] = 2.00 mol CaO
NH
Cl: 224 g NH
Cl x {1 mol/[14.007 g + 4(1.008 g) + 35.453 g]} = 4.19 mol NH
Cl
4
4
4
Cl ! ! ! ! Have that much
Need 2.00 mol CaO x (2 mol NH
Cl/1 mol CaO) = 4.00 mol NH
4
4
Cl) = 2.10 mol CaO ! ! ! ! Do not have that much
Need 4.19 mol NH
Cl x (1 mol CaO/2 mol NH
4
4
Thus, CaO is limiting reagent
b) Calculate the maximum yield of NH
.
3
2.00 mol CaO x (2 mol NH
/1 mol CaO) = 4.00 mol NH
3
3
4.00 mol NH
x {[14.007 g + 3(1.008 g)/1 mol NH
} = 68.1 g NH
3
3
3

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