Review
Ch6
Ch5+7
Ch8
Ch9 + Ch10
100
What are the rules when it comes to sig figs
all non-zero digits are significant, zeros between significant digits are significant, leading zeros are not, and trailing zeros are only significant if there is a decimal point. The result of multiplication or division should have the same number of significant figures as the factor with the fewest, while the result of addition or subtraction should be rounded to the least number of decimal places among the values used.
100
What is the first law of thermodynamics? How can we use these to solve problem related to ch6?
100
A gas sample initially occupies 2.0 L at 1.0 atm. If the temperature stays constant, explain why the pressure changes when the volume is decreased, and calculate the new pressure when the volume becomes 0.50 L.
Pressure increases because decreasing volume increases collision frequency;
P₂ = P₁V₁ / V₂ = (1.0)(2.0) / 0.50 = 4.0 atm
100
please explain aufbau principle, Pauli exclusion principle, hands rule and how they relate to electron configuration
Electrons will occupy the lowest energy orbitals that they can enter, No two two electrons within an atom have the same four quantum numbers, Electrons in a sub shell containing more than one orbital will spread out among the orbitals with as many of their spins in the same direction as possible
100
Describe the steps you would take to identify the shape of xyz molecule
Draw out lewis structure, figure out #of bonds, locate that number on VSPER chart, and then look out number of lone pairs and thats your shape
200
What is the empirical formula of vitamin c, if it contains 40.92% C, 4.58% H, and 54.5% O by mass
C3H4O3
200
What is the formula for calorimetry and how does it differ for an object, moles of a pure substance, or a mixture of known mass?
CAT, nCAT, MCAT
200
An electron is ejected from a metal when it is exposed to 300 nm light. Explain why not all wavelengths eject electrons, and calculate the energy of a single photon of this light.
Only frequencies above threshold supply enough energy to overcome the work function;
E = hc/λ = (6.626×10⁻³⁴)(3.00×10⁸) / (3.00×10⁻⁷) = 6.63×10⁻¹⁹ J
200
please write out the electron configurations and orbital diagram for Cl+
Cl⁺ has 16 electrons with the configuration 1s² 2s² 2p⁶ 3s² 3p³, giving it three unpaired electrons in the 3p orbital, making it paramagnetic.
200
what is the relationship between bond order and bond length? What about bond order and strength?
inverse relationship, direct relationship
300
When 11.5 g of ethanol is burned in oxygen, 22.0 g of CO2 and 13.5 g of H2O is produced. Ethanol contains only C, H, and O. Find the empirical formula of ethanol (hint: all the C is converted to CO2, all the H is converted to H2O)
C2H6O
300
A styrofoam cup contains 75.0 mL of water at 25.0C. A small steel spoon, just removed from a boiling water, fell into the styrofoam cup. What is the temperature of water after the thermal equilibrium is reached? The mass of the spoon is 34 g .
Assume that:
1) there is no loss of water (through evaporation),
2) there is no loss of heat to the outside of the styrofoam cup,
3) while waiting for thermal equilibrium to be reached, the styrofoam cup absorbed 67 J of heat. (Specific heat of steel is 0.45 J/(g C ), density of water at 25.0C is 0.9970 g/mL .)
28 C
300
At constant volume, the temperature of a gas increases from 300 K to 450 K.
Explain why pressure rises at the particle level, and calculate the factor by which pressure changes.
Higher temperature → higher particle KE → more frequent + forceful collisions;
P₂/P₁ = T₂/T₁ = 450/300 = 1.5× increase
300
explain the trend for ionization energy and electron affinity
Increase across the period and decrease down the group
300
explain the trend in electronegativity? what is electronegativity and how does it differ from electron affinity
increases across the period and decreases down the group
400
100.0 g H2O are allowed to react with 150.0 g NO in the reaction below:
6H2O(l) + 4NO(g) -> 4NH3(g) + 5O2(g)
1. Which reagent is limiting?
2. What mass of O2 will form?
3. What mass of excess reagent will remain unreacted?
H2O, 148.0g, 39.0 g NO
400
A quantity of of 1.00 * 10^2 mL of 0.500 M HCl is mixed with 1.00 * 10^2 mL of 0.500 M NaOH in a constant-pressure calorimeter having a heat capacity of 335 J/C. The initial temperature of the HCl and NaOH solutions is the same, 22.50C, and the final temperature of the mixed solution is 24.90C. Calculate the change in enthalpy for the neutralization reaction. Assume that the specific heats of the solutions and their densities are the same as those of pure water, 4.184 J/g C and 1.00 g/mL , respectively
-2812.32 J
400
An electron moves with a speed of 2.5×10⁶ m/s. Explain conceptually why matter exhibits wave properties, and calculate the electron’s de Broglie wavelength.
Electrons behave as waves because their momentum is small enough for λ = h/p to be measurable; λ = h/(mu) = (6.626×10⁻³⁴) / [(9.11×10⁻³¹)(2.5×10⁶)] ≈ 2.9×10⁻¹⁰ m
400
what is the difference between paramagnetism and diamagnetism, and identify the magnetic properties of Cl- and Cl(which one is para/di magnetic)
Paramagnetism involves unpaired electrons and attraction to magnetic fields, while diamagnetism involves only paired electrons and slight repulsion; thus, Cl is paramagnetic and Cl⁻ is diamagnetic.
400
State the electronegativity differences between the three bond characteres(nonpolar covalent, polar covalent, ionic)
0-0.4, 0.4-1.7, >1.7
500
When 2.00 * 10^2g of nitroglycerin, C3H5N3O9, decomposes
4C3H5N3O9(l) -> 6N2(g) + 12CO2(g) + 10H2O(g) + O2(g)
Molar mass of nitroglycerin is 227.10
What is the theoretical yield of O2
If the actual yield is 6.55 g O2, what is the % yield?
7.05 g O2, 93.0%
500
A quantity of 1.435 g of naphthalene (C10H8) was burned in a constant-volume bomb calorimeter. Consequently, the temperature of the water rose from 20.17C to 25.84C. If the quantity of water surrounding the bomb (dry parts) was 2.000 * 103 g and the heat capacity of the bomb was 1.80 kJ/C, calculate the heat of combustion (for constant-volume) of naphthalene on a molar basis.
-5.15 * 10^3 kJ/mol
500
Two gases, He (MM = 4 g/mol) and CO₂ (MM = 44 g/mol), are released simultaneously.
Explain why lighter gases move and effuse faster, and calculate the ratio of their effusion rates using Graham’s law.
Lighter gases have higher rms speeds at the same temperature; Rate₍He₎ / Rate₍CO₂₎ = √(44/4) = √11 ≈ 3.32
500
What are the two exceptions in which the 1s22s2 trend is not followed, but the half filled subshells are exceptionally stable and will fill first before the next higher energy sub level
Cr: 4s13d5, Cu:4s13d10
500
Predict the molecular geometry of ClF3
T-shaped(go over how to use VSPER diagram for these problems)