Random
Stoichiometry
Atomic Structure
Molecular structure, states of matter, Bonding
Equations
100
Which species is reduced in the reaction 2 Al(s) + 3 MnO2(s)---> Al2O3(s) + 3 Mn(s)?
Mn
In the reaction, MnO2 is reduced to Mn, meaning Mn gains electrons.
100
If 7.0 grams of nitrogen reacts with 3.0 grams of hydrogen, how many grams of ammonia are produced?
8.5 grams
The balanced equation for the reaction is N2 +3H2--> 2NH3. Nitrogen has a molar mass of 28 g/mol, so 7.0 grams is about 0.25 moles. Hydrogen has a molar mass of 2 g/mol, so 3.0 grams is 1.5 moles. Nitrogen is the limiting reagent and fully reacts to form ammonia. The molar ratio of nitrogen to ammonia is 1:2, hence 0.25 moles of nitrogen will produce 0.5 moles of ammonia, corresponding to 8.5 grams (17 g/mol x 0.5 moles).
100
Which is the correct electron configuration for the outer shell of a bromine atom in the ground state? (noble gas configuration)
Bromine (atomic number 35) has a ground state electron configuration of [Ar] 4s^2 3d^10 4p^5
100
What differs in an isotope from the general element?
There is a different number of neutrons!
(same number of protons)
100
Molality
moles/kg
200
What is the oxidation state of chromium in K2Cr2O7?
+6
In K2Cr2O7, potassium has an oxidation state of +1 and oxygen has -2. Solving for chromium gives it an oxidation state of +6.
200
In the reaction where calcium carbonate decomposes into calcium oxide and carbon dioxide, how much carbon dioxide can be produced from 50 grams of calcium carbonate?
MM CO2= 44g/mol
MM CaCO3= 100g/mol
22 grams
The balanced chemical equation for the decomposition of calcium carbonate (CaCO3--> Ca0 + CO2) is . The molar mass of CaCO3 is approximately 100 g/mol, so 50 grams corresponds to 0.5 moles of CaCO3 . The molar mass of CO2 is approximately 44 g/mol, hence .5 x 44 = 22grams of can be produced.
200
Which quantum number determines the shape of an electron orbital?
The azimuthal quantum number (l) determines the shape of an electron orbital.
For example, l = 0 corresponds to s orbitals (spherical), l = 1 to p orbitals (dumbbell-shaped), etc.
200
In terms of molecular movement, how do gases differ from liquids?
Molecules in gases move faster and are further apart than in liquids.
200
Molarity
moles/volume
300
A reaction mechanism consists of two steps: A->B (slow) and B+C-->D (fast). What is the rate-determining step?
A-->B
The slowest step in a reaction mechanism is the rate-determining step, which in this case is. A-->B
300
What volume of carbon dioxide at STP is produced from the combustion of 100 grams of butane (C4H10)?
336L
The balanced equation for the combustion of butane is 2C4H10 +13O2--> 8CO2 + 10H2O). The molar mass of butane is approximately 58 g/mol, so 100 grams corresponds to approximately 1.72 moles of butane. Each mole of butane produces 4 moles of CO2, hence 1.72 moles butane x 4 mole CO2 x 22.4 mole per liter=336 liters of CO2 at STP.
300
What is the total number of orbitals in the third energy level (n=3) of an atom?
9
The third energy level includes the 3s, 3p, and 3d sublevels, which have 1, 3, and 5 orbitals respectively. Thus, there are a total of 9 orbitals (1+3+5).
300
Which intermolecular force is primarily responsible for the high boiling point of water compared to hydrogen sulfide?
hydrogen bonding
300
Ideal Gas Law
PV=nRT
400
For a process that absorbs 40 kJ of heat and does 15 kJ of work on the surroundings, what is the change in internal energy of the system?
+25kJ
change in U= q+w
q=+40kJ (heat absorbed)
w= -15kJ (work done BY system so negative)
400
What is the limiting reagent when 3.0 grams of Al react with 4.0 grams of O2 to form aluminum oxide?
Al= limiting reagent
The balanced equation is 4Al + 3O2--> 2Al2O3. Aluminum has a molar mass of about 27 g/mol, so 3.0 g of Al is about 0.111 moles. Oxygen has a molar mass of about 32 g/mol, so 4.0 g of O2 is about 0.125 moles. The stoichiometry requires more moles of Al than O2 per the balanced equation, making Al the limiting reagent.
400
The Aufbau principle states that:
Electrons fill lowest energy levels first
400
What best describes the bonding in benzene, C6H6?
a) Ionic bonding, b) Sigma bonding only, c) Pi bonding only, or d) Sigma and delocalized pi bonding
d) Sigma and delocalized pi bonding
Benzene has sigma bonds between adjacent carbon atoms and delocalized pi bonds above and below the plane of carbon atoms, contributing to its aromatic stability.
400
Raoult's Law
Psolution= Xsolvent (Psolvent)
= vapor pressure of the solution
= mole fraction of the solvent
= vapor pressure of the pure solvent
500
How many electrons are transferred in the balanced redox reaction involving the conversion of Cu to Cu2+ and Ag+ to Ag?
2 electrons
The reaction Cu-->Cu2+ involves the loss of two electrons, and each Ag+ gains one electron to form Ag. Overall, two electrons are transferred.
500
If 5.0 moles of propane (C3H8) are burned completely in excess oxygen, how many moles of carbon dioxide are produced?
15 moles
The balanced equation for the combustion of propane is C3H8 + 5O2---> 3CO2 + 4H2O. For every mole of propane burned, 3 moles of CO2 are produced. Thus, 5x3 =15 moles of CO2 are produced.
500
Which electron configuration is possible for an atom in an excited state?
a) 1s^2 2s^2 2p^6
b) 1s^2 2s^2 2p^5 3s^1
c) 1s^2 2s^2 2p^6 3s^2
d) 1s^2 2s^2 2p^6 3p^1
b) 1s^2 2s^2 2p^5 3s^1
This configuration shows an electron has been excited from the 2p orbital to the 3s orbital, which is typical of an excited state.
500
What is the effect of adding a non-volatile(does not easily vaporize) solute to a solvent on the boiling point of the solvent?
Increases the boiling point
Adding a non-volatile solute to a solvent increases the boiling point of the solution, a phenomenon known as boiling point elevation, which is due to the lowering of the vapor pressure.
500
Gibbs Free Energy Equation
ΔG° = ΔH° - TΔS°