Download chem eng-problems

1) Convert the following
1) 125 g to Kg
6) 26.9 dm3 to cm3 11) 1.8µL to cm3
2) 21.3 Km to cm
7) 18.2 ml to cm3
12) 2.45 L to µm3 17) 1.2 m to inches 22) 180 ºC to K
3) 3.34 mm to cm
8) 728 nm to m
13) 40.4 Km to cm 18) 27.4 Kg to lb
23) 540F to ºC
4) 1.23 ml to L
9) 8.32 cg to mg
14) 8.98 mg to g
19) 0.25 lb to g
24) 5000K to ºC
5) 47.5 cm3 to L
10) 4.978 Mg to dg 15) 50.1 mm to
Km
20) 6'4" to cm
25) 27ºC to F
16) 4.8 lb to Kg
21) 23 F to K
2) Scientific Notation
Complete the following calculations and express the answers in scientific notation.
1) [3.0 x 10-3][2.0 x 105]=
4)[ 4.6 x 101][2.1 x 10-4]=
[1.64 x 1034]
7) [ 2.3 x 1014]=
[4.17 x 109]
2) [27.3 x 10-22][2.0 x 1018]=
5)[ 4.2 x 1014][9.4 x 107]=
[6.4 x 109]
8) [789.23 x 102][0.0045 x 1015]=
3) [ 1.7 x 109][3.9 x 107]=
[1.40 x 10-6]
6) [ 4.50 x 109]=
[6.636 x 10-34]
9)[7.4 x 106][1.9 x 10-3]
=
[5.3 x 106][1.7 x 10-8][2.4x 105]
Density Problems
1) What is the volume of a tank that can hold 18 754 Kg of methanol whose
density is 0.788g/cm3?
3) CaCl2 is used as a de-icer on roads in the winter. It has a density of 2.50 g/cm3.
What is the
mass of 15.0 L this substance?
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1. What is average atomic mass of Lithium if 7.42% exists as 6Li (6.015 g/mol) and
92.58% exists as 7Li (7.016 g/mol)?
2. Magnesium has three naturally occuring isotopes. 78.70% of Magnesium atoms
exist as Magnesium-24 (23.9850 g/mol), 10.03% exist as Magnesium-25 (24.9858
g/mol) and 11.17% exist as Magnesium-26 (25.9826 g/mol). What is the average
atomic mass of Magnesium?
3. Neon has two major isotopes, Neon-20 and Neon-22. Out of every 250 neon atoms,
225 will be Neon-20 (19.992 g/mol), and 25 will be Neon-22 (21.991 g/mol). What is
the average atomic mass of Neon?
4. In a sample of 200 Chlorine atoms, it is found that 151 are 35Cl (34.969 g/mol), and
49 are 37Cl (36.966 g/mol). What is the average atomic mass of Chlorine?
5) When copper (II) chloride reacts with sodium nitrate, copper (II) nitrate and
sodium chloride are formed.
(1
Write the balanced equation for the reaction given above:
(2
If 15 grams of copper (II) chloride react with 20 grams of sodium nitrate, how
much sodium chloride can be formed?
(3
What is the limiting reagent for the reaction in #2__________________ ?
(4
How much of the nonlimiting reagent is left over in this reaction?
(5
If 11.3 grams of sodium chloride are formed in the reaction described in
problem #2, what is the percent yield of this reaction?
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Mole Problems
Molecular Mass / Formula Mass
1) Find the formula mass of KMnO4.
2) Find the formula mass of Mg3(PO4)2.
3) Find the molecular mass of C12H22O11.
Conversion of Moles, Grams, Molecules, and Atoms
1) How many moles are in 17.7 g of KMnO4?
How many formula units are in 17.7 g KMnO4?
How many atoms of O are in 17.7 g KMnO4?
2) How many moles are in 41.2 g of Mg3(PO4)2?
How many formula units are in 41.2 g Mg3(PO4)2?
How many atoms of P are in 41.2 g Mg3(PO4)2?
3) How many moles are in 26.9 g of C12H22O11?
How many molecules are in 26.9 g of C12H22O11?
How many atoms of C are in 26.9 g of C12H22O11?
4) How many moles are 19.8 x 1024 molecules C12H22O11?
What is the mass of 19.8 x 1024 molecules C12H22O11?
5) How many moles of Mg3(PO4)2 are 27.6 x 1037 atoms of O in Mg3(PO4)2?
6) How many moles of KMnO4 are 3.64 x 1025 atoms of Mn in KMnO4?
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Percent Composition
1) Find the percentage composition of KMnO4.
2) Find the percentage composition of Mg3(PO4)2.
3) Find the percentage composition of C12H22O11.
Empirical Formula
1) What is the empirical formula for a compound if a 83.7 g sample contains 44.28g Al
and 39.42 g O?
2) What is the empirical formula for a compound if a 55.0 g sample contains
22.0 g C, 3.67 g H, and 29.33 g O?
Molecular Formula
1) A compound has a percentage composition of 40.01% C, 6.69 % H, and 53.30%
O. Its molecular mass is 179.9 amu. What is it's empirical formula? What is it's
molecular formula?
2) A compound has a percentage composition of 46.68% N and
53.32% O.
Its
molecular mass is 59.98 amu. What is the empirical formula? What is it's molecular
formula?
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Balancing Chemical Equations
Predict the products and write the balanced equation for the reactions.
1. Mg + AgNO3 -->
2. Ba + H2SO4 -->
3. CaCl2 + NaOH -->
4. O2 + H2 -->
5. SiO2 -- >
Write balanced equations for each of the following reactions.
1.) Fe + O2 -> Fe2O3
2.) KClO3 -> KCl + O2
3.) Ca(OH)2 + H2SO4 -> HOH + CaSO4
4.) HgO -> Hg + O2
5.) Cu + AgNO3 -> Cu(NO3)2 + Ag
6.) C4H10 + O2 -->
7.) C9H20 + O2 -->
8.) CrCl3 + NaOH--> Cr2O3 + HCl + NaCl
9.) NaClO3 --> NaCl + O2
10.) C23H48 + O2 -->
1) Select the correct group of coefficients for the following neutralization
equations
__AlCl3 + __ H2O
A.
__ HCl + __ Al(OH)3
a) 1 ,3 ,3 ,1
B.__ Ba(OH)2 + __H3PO4
a)2 ,2 ,2 ,3
b) 1 ,1 ,1 ,3
c)3 ,1 ,1 ,3
__Ba3(PO4)2 + __ H2O
b) 6 ,1 ,3 ,3 c)
5
6 ,1 ,3 ,2
Stoichiometry Problems
1a) How many moles of chlorine gas (Cl2) would react with 5 moles of sodium (Na)
according to the following chemical equation? (Balance equation.)
Na + Cl2 --> NaCl
1b) Using the equation (after it is balanced) above, determine the amount of product that
can be produced from 24.7 g Na.
1c) How many molecules of product would be produced from 24.7g Na?
2a) In the reaction 2C8H18 + 25O2 --> 16CO2 + 18 H2O, the ratio of volumes of O2 to
CO2 is
2b) If 27.3g of C8H18 are combusted, what mass of water will be produced?
2c) How many molecules of CO2 will be produced?
2d) How many atoms of H are in 2 mol of C8H18?
2e) What is the percentage, by mass, of the H in 2 mol of C8H18?
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Molarity Problems
1) How many grams of potassium carbonate are needed to make 200 mL of a 2.5
M solution?
2) How many liters of 4 M solution can be made using 100 grams of lithium
bromide?
(3 What is the concentration of a 450 mL solution that contains 200 grams of iron (II)
chloride?
(4 How many grams of ammonium sulfate are needed to make a 0.25 M solution at a
concentration of 6 M?
5) What is the concentration of a solution that has a volume of 2.5 L and contains 660
grams of calcium phosphate?
Dilutions problems
1) If I have 340 mL of a 0.5 M NaBr solution, what will the concentration be if
you add 560 mL more water to it?
2) If I dilute 250 mL of 0.10 M lithium acetate solution to a volume of 750 mL, what
will the concentration of this solution be?
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1) Which of the following compounds is likely soluble in water?
Compound
Fe(NO3)3
soluble
Insoluble
AgCl
CaCO3
(NH4)2SO4
CuSO4
Cu(OH)2
2) Complete the following equations and determine whether or not a precipitation
reaction (exchange reaction) will occur. If a reaction will occur, balance the equation
and 1) Determine the products of exchange reaction 2) Determine if there is any
insoluble product 3) Balance the chemical equation
1) Pb(NO3)2 (aq) + KI (aq) →
2) Mg(NO3)2 (aq) + KCl (aq) →
3) Balance the following chemical equation and write the (complete) Ionic equation
And the net Ionic equation and then determine the spectator ions
1) Pb(NO3)2 (aq) + KI (aq) PbI2 (s) + KNO3 (aq)
4) Write the net ionic equation for the precipitation reaction that may occur when
solutions of calcium nitrate Ca(NO3)2 and sodium acetate (CH3COONa) are mixed.
Write the balanced molecular equation, Check the solubility of products and
determine the spectator ions
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5) Complete and balance the following equation for an acid-base neutralization
reaction:
H3PO4(aq) + KOH(aq) →
What is the net ionic equation?
6) What is the net ionic equation for the reaction between Na2CO3(aq) and HCl(aq)?
7) Which of these reactions will react and give products? (Based on activity series)
Fe
+ CuSO4
→
Ni
+ NaCl
→
Li
+ ZnCO3
→
Al
+ CuCl2
→
Mg
+ AgNO3
→
Cu
+ AgNO3
→
Mg
+
H2SO4 →
Zn
+
AgNO3 →
Cu
+
Fe(NO3)3 →
Cl2
+
2KBr
→
oxidation number
1) In H2SO4 (sulfuric acid), calculate the oxidation number of the Sulfur atom?
Write the oxidation number of each atom
a. NaOH
Na = ___;
O = ___;
b. HCl
H = ___;
Cl = ___
c. N2O3
N = ___;
O = ___
Ca = ___;
C = ___;
e. SF6
S = ___;
F = ___
f. H2Se
H = ___;
Se = ___
g. H2O2
H = ___;
O = ___
d. CaC2O4
H = ___
O = ___
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Write the oxidation number of each atom in these ions:
2-
1. SO
4
2. HPO
3. NO
4. OH
23
-
O = ___
H = ___
; P = ___; O = ___
N = ___;
2
-
5. HSO
S = ___;
4
6. HAsO
24
O = ___
O = ___;
H = ___
H = ___;
S = ___;
O = ___
H = ___;
As = ___;
O = ___
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