LUOA chemistry semester exam review 2023 with
complete solution
How many molecules are in 3.9 moles of water?
2.3 x 10^24 molecules of water
How many moles are in 3.75 x 10^24 molecules of CO2?
6.23 moles
How many moles are in 1.16 x 10^25 atoms of H2CO3?
19.3 moles of H2CO3
The molar mass of Cu(OH)2 is _________ grams per mole.
(Hint: Answers might vary slightly, but should still fall within an acceptable range
for the correct answer)
97.55
How many moles are in 132.3 grams of carbon dioxide?
(Hint: Answers might vary slightly, but should still fall within an acceptable range
for the correct answer)
3.007 moles
How many grams are in 3.396 moles of Al2S3?
(Hint: Answers might vary slightly, but should still fall within an acceptable range
for the correct answer)
509.9 grams
Calculate the mass of carbon in 250 g C2H6
199.72 grams
Calculate the mass of hydrogen in 250 g C2H6
50.28 grams
Calculate the mass of hydrogen in 250 g of C2H3O2
12.83 grams
Methyl acetate has a chemical composition of 48.64% carbon, 8.16% hydrogen,
and 43.20 % oxygen. What is the empirical formula?
C3H6O2
A(n) __________formula is one that shows the lowest whole number ratio of the
elements in a compound>
empirical
If the empirical formula of a compound is C2OH4 and has a molar mass of 88
g/mol, what is its molecular formula?
C4O2H8
Write the formula for copper (II) sulfate hexahydrate.
CuSO4 ∙ 6H2O
N2+ 3H2--> 2NH3
How many moles of ammonia are produced when 5 moles of hydrogen reacts
with excess nitrogen?
3.3 mol
, N2+ 3H2--> 2NH3
In a certain reaction, 5.0 moles of hydrogen is reacted with excess nitrogen. To
determine how many moles of ammonia (NH3) are produced based on the 5 mols
of hydrogen, what conversion factor(s) should be used? (choose all that apply)
(2 mol NH3)/(3 mol H2)
(3 mol H2)/(2 mol NH3)
2NO(g) + O2 (g) --> 2NO2
How many grams of NO are required to react fully with 5.00 mol of O2?
300 g
2 NO(g) + O2 (g) --> 2 NO2 (g)
What mass of NO2 is produced by the reaction of 2.40 mol NO with excess
oxygen?
110.4 g
4 Fe(s) + 3O2(g) --> 2Fe2O3(g)
In a certain reaction, 27.3 g of iron is reacted with 45.8 g of Oxygen.
What is the limiting reactant?
Fe
4 Fe(s) + 3O2(g) -->2Fe2O3(g)
In a certain reaction, 27.3 g of iron is reacted with 45.8 g of Oxygen.
How many grams of the excess reactant remain after the reaction is complete
33.9 g
What pieces of information do we need in order to calculate percent yield?
the maximum amount possible of product and the amount experimentally recovered
What factors can contribute to a percent yield that is less than 100%?
-unwanted side reaction
-incomplete reaction
-spills during the experiment
Select the best description of the path of gas particles in a given sample of gas?
straight path which changes upon collisions with other particles
Pressure is:
force/area
___ kPa = 14.7 psi
101.3 kPa
Identify the correct ranking of intermolecular bonds or forces in order from
strongest to weakest is:
hydrogen bond, dipole-dipole force, dispersion force
In water molecules, the oxygen atoms have a slightly _____ charge, while the
hydrogen atoms has a slightly _____ charge.
negative; positive
complete solution
How many molecules are in 3.9 moles of water?
2.3 x 10^24 molecules of water
How many moles are in 3.75 x 10^24 molecules of CO2?
6.23 moles
How many moles are in 1.16 x 10^25 atoms of H2CO3?
19.3 moles of H2CO3
The molar mass of Cu(OH)2 is _________ grams per mole.
(Hint: Answers might vary slightly, but should still fall within an acceptable range
for the correct answer)
97.55
How many moles are in 132.3 grams of carbon dioxide?
(Hint: Answers might vary slightly, but should still fall within an acceptable range
for the correct answer)
3.007 moles
How many grams are in 3.396 moles of Al2S3?
(Hint: Answers might vary slightly, but should still fall within an acceptable range
for the correct answer)
509.9 grams
Calculate the mass of carbon in 250 g C2H6
199.72 grams
Calculate the mass of hydrogen in 250 g C2H6
50.28 grams
Calculate the mass of hydrogen in 250 g of C2H3O2
12.83 grams
Methyl acetate has a chemical composition of 48.64% carbon, 8.16% hydrogen,
and 43.20 % oxygen. What is the empirical formula?
C3H6O2
A(n) __________formula is one that shows the lowest whole number ratio of the
elements in a compound>
empirical
If the empirical formula of a compound is C2OH4 and has a molar mass of 88
g/mol, what is its molecular formula?
C4O2H8
Write the formula for copper (II) sulfate hexahydrate.
CuSO4 ∙ 6H2O
N2+ 3H2--> 2NH3
How many moles of ammonia are produced when 5 moles of hydrogen reacts
with excess nitrogen?
3.3 mol
, N2+ 3H2--> 2NH3
In a certain reaction, 5.0 moles of hydrogen is reacted with excess nitrogen. To
determine how many moles of ammonia (NH3) are produced based on the 5 mols
of hydrogen, what conversion factor(s) should be used? (choose all that apply)
(2 mol NH3)/(3 mol H2)
(3 mol H2)/(2 mol NH3)
2NO(g) + O2 (g) --> 2NO2
How many grams of NO are required to react fully with 5.00 mol of O2?
300 g
2 NO(g) + O2 (g) --> 2 NO2 (g)
What mass of NO2 is produced by the reaction of 2.40 mol NO with excess
oxygen?
110.4 g
4 Fe(s) + 3O2(g) --> 2Fe2O3(g)
In a certain reaction, 27.3 g of iron is reacted with 45.8 g of Oxygen.
What is the limiting reactant?
Fe
4 Fe(s) + 3O2(g) -->2Fe2O3(g)
In a certain reaction, 27.3 g of iron is reacted with 45.8 g of Oxygen.
How many grams of the excess reactant remain after the reaction is complete
33.9 g
What pieces of information do we need in order to calculate percent yield?
the maximum amount possible of product and the amount experimentally recovered
What factors can contribute to a percent yield that is less than 100%?
-unwanted side reaction
-incomplete reaction
-spills during the experiment
Select the best description of the path of gas particles in a given sample of gas?
straight path which changes upon collisions with other particles
Pressure is:
force/area
___ kPa = 14.7 psi
101.3 kPa
Identify the correct ranking of intermolecular bonds or forces in order from
strongest to weakest is:
hydrogen bond, dipole-dipole force, dispersion force
In water molecules, the oxygen atoms have a slightly _____ charge, while the
hydrogen atoms has a slightly _____ charge.
negative; positive
