C125 final

Which of the following is used to represent accuracy of a measurement? Standard deviation Mean of experimental data number of decimal places % error

% error

What is the oxidation state of S in K2S2O3?

+2

What is the oxidation state of C in oxalate ion, C2O42-?

+3

Draw the best Lewis structure of N2O. What is the formal charge of O?

-1

What is the slope if B is plotted on y-axis and A is plotted on x-axis? 5A + 3B = 8

-5/3

100.0 mL of 1.00 mol/L NaOH reacted with 56.5 mL of 1.00 mol/L CH3COOH solution and the temperature increased from 20 to 22 C. How many moles of NaOH get and CH3COOH are neutralized?

.0565

If a Fe stock solution has a concentration of 1.6 mg/mL, what is the concentration when 2 mL of this stock solution is diluted to 50. mL?

.064

How many moles of NaOH will be needed to neutralize 0.18 mol of H2SO4? Keep 2 decimal places for your answer. Hint: Write out and balance the chemical equation first!!

.36

inHg is commonly used as unit of atmospheric pressure. It indicates the height of Hg (in inch) that atmospheric pressure can support. If atmospheric pressure is 27.6 inHg, what is it in atm? Use standard notation and 3 sig figs for your final answer. Given: 1 in = 2.54 cm = 25.4 mm; 1 atm = 760 mmHg

.922

How many moles of NaOH are there in 22.5 mL of 0.73 mol/L NaOH solution? Keep 3 decimal places for your answer.

0.0160

Which of the following should not be rounded up when keeping 3 sig figs? 0.05464 1.0381 999.9 12.56

0.05464

Which of the following has the lowest concentration of H+? They all have the same concentration of H+ 0.1 mol HCl 0.1 mol HNO3 0.1 mol CH3COOH

0.1 mol CH3COOH

What is the absorbance if the % transmittance is 53%

0.28

At constant pressure, density of gas is inversely proportional to its temperature. This is how hot air balloon is floating in air: burning fuel makes inside air temperature higher and density lower; low density air balloon float on high density regular air. What is the density of air in g/L at 55 degree C if the atmospheric pressure is 1.0 atm? The average molar mass of air is about 29 g/mol. Keep two decimal places for your answer.

1.08

How many moles of NaOH will be needed to neutralize 0.7 mol of H2SO4? The following equation is NON-balanced: NaOH + H2SO4 --> Na2SO4 + H2O

1.4

If 12.1 g of NaCl is dissolved in 100. g of water, what is the mass % concentration of NaCl in this solution?

10.8

At equal mass, will 100 C water or 100 C steam cause more serious burn? Why? 100 C water because it is hotter 100 C water because evaporation of water is endothermic 100 C steam because condensation of steam is exothermic 100 C steam because it occupies a bigger volume

100 C steam because condensation of steam is exothermic

Several balloons of He gas are kept at different temperature, but at the same pressure. At which temperature does the gas have the highest density? 400 K 200 K 300 K 100 K

100K

The molar mass of butane (C4H10) should be 58 g/mol (as calculated from periodic table). If a student measured the molar mass of butane to be 65, what is the % error of the measurement?

12%

How many grams are there in 0.2 moles of acetic acid, (CH3COOH, 60 g/mol)? Keep one decimal place for your answer.

12.0

Which one is not rounded correctly when keeping 3 sig figs? 1387 to 1.39*103 123.4 to 123 1.0250 to 1.02 12.451 to 12.4

12.451 to 12.4

Masses (m, in g) and volumes (V, in mL) of different amount of an unknown liquid were plotted in Excel and the following best-fit-line equation is obtained: m = 0.781 V + 0.026 If you were asked to obtain 10. g of this liquid, how many mL you should measure out with a graduated cylinder?

12.77

What is the bond angle in BF3?

120

If a sample increased its temperature by 15 degree Celsius, what is the temperature change in degree Kelvin?

15

How many unpaired electrons are there in O2?

2

The lines observed in H-lamp are parts of Balmer Series. All these lines are due to a transition from various higher n value to a common n. What is this common lower n value for all these lines?

2

Deflate Gate has been a hot topic before Super Bowl. According to NFL rule, the football used should be inflated no less than 12 psi. Approximately, what is the REAL pressure of air inside a football when it is inflated to 12 psi? Assume the atmospheric pressure is about 15 psi. 27 psi 15 psi 12 psi 3 psi

27 psi

If we apply the HOMO and LUMO concepts in atomic orbitals, we will have HOAO (Highest Occupied Atomic Orbitals) and LUAO (Lowest Unoccupied Atomic Orbitals). What is the HOAO of O atom?

2p

100. g water, at 20 C, and 100. g copper, at 80 C, are mixed in a well-sealed calorimeter. Without any calculation, predict a reasonable final temperature after thermal equilibrium is reached. Select the best option! Hint: Without looking up the specific heats of both water and copper, students should know that specific heat of water should be much higher than that of copper. 30 C 50 C 100 C 10 C 60 C

30 C

At STP, 0.106 g of a gas sample occupies a volume of 62.2 mL. What is the molar mass of this gas? Keep 3 sig figs for your final answer.

38.3

A metal sample, at 20. degree Celsius, has a heat capacity of 0.25 J/C. How much heat it must absorb to increase its temperature to 36 degree Celsius?

4.0

A 100-mL sample of Pb initially has a concentration of 12.4 ppm. If this sample was diluted to 300 mL, what is the new concentration in ppm?

4.1

A pressure gauge was used to measure the air pressure inside a tire. If the pressure gauge reads 26 psi, what is the real pressure in psi of air inside this tire? Assume atmospheric pressure is 15 psi.

41

The only electron in a hydrogen atom moved from n=2 to n=4. What is the wavelength of photon (in nm) being associated with this transition?

487

Which of the following orbitals of H has the highest energy? 4s 3d 2p 1s

4s

Given: In Atomic Spectra lab, a student obtained his best-fit line equation to be y = 0.29 x + 46.8 when he plotted his Vernier reading on the y-axis and wavelength in nm on the x-axis. Question: If the Vernier reading for a line is 196.8, what is the predicted wavelength of this line in nm?

517.2

How many valence electrons are there in a Br atom?

7

A water sample with unknown mass absorbed 100.0 J of heat and the temperature increased from 25.0 C to 28.3 C. What is the mass of this water sample? Specific heat of water = 4.184 J/(gC).

7.2

If 8 g of NaCl is dissolved in 100. g of water, what is the mass % concentration of NaCl in this solution? Use one decimal place for your answer.

7.4%

A student tried to measure density of a metal by water displacement. Before putting the metal in, water volume was 10.26 mL. After putting metal in, water volume increased to 12.42 mL. If this piece of metal has a mass of 21.46 g, what is the density of this metal?

9.935

A student used Re-dox titration in Coordination lab to determine the %Purity of K3[Fe(C2O4)3]*3H2O crystals. She did 3 titrations and the average % purity was 92.71% and the standard deviation of these three titrations was 0.61%. How should her result be reported in a "mean +/- st. dev." format?

92.7 +/- 0.6 %

Butane gas was collected in a graduated cylinder over water in Gas Laws lab. If the water vapor pressure at the given temperature is 2.2 kPa and the atmospheric pressure is 100.9 kPa, what is the pressure of butane in kPa inside the graduated cylinder? Keep one decimal place for your final answer.

98.7

Butane gas will be collected in a graduated cylinder over water. Immediately before reading the volume of gas inside the graduated cylinder, the student must: Ajust the water level of graduated cylinder unplug the tube from the butane can measure the water temperature Dry and weigh the butane can.

Ajust the water level of graduated cylinder

Which one is correct about the bond lengths in PCl5? All P-Cl bonds have the same bond length. Equitorial bonds are longer because they experience smaller repulsion The axial bonds are shorter because they are far away from other bonds Axial bonds are longer because they experience higher repulsion

Axial bonds are longer because they experience higher repulsion

At constant temperature, the volume of a gas is inversely proportional to its pressure. This is Avogadro's Law Charles' Law Boyle's Law Ideal Gas Law

Boyle's Law

Rearrange the following equation to solve for C. A=(-B/C)+D

C=B/(D-A)

Which of the following is not a base? There are multiple correct answers and check all of them. OH groups are highlighted. NaOH CH3COOH Ba(OH)2 CH3OH

CH3COOH CH3OH

In Vinegar Analysis lab, the end point is reached when the final drop of NaOH makes the mixture basic, which turn the pH indicator pink. However, if we put the flask on the bench long enough, the pink color may eventually disappear due to some substance from the air. What substance from air is causing the pink color of pH indicator to disappear? H2O moisture to dilute the solution and make the pink color too light to be seen. N2 CO2 to neutralize the small amount of NaOH O2 to oxidize the pH indicator

CO2 to neutralize the small amount of NaOH

Idea of single displacement reaction: 1. Stronger metal can displace weak metal or hydrogen out of their compound. 2. Stronger halogen can displace weaker halogen out of their compound. Which halogen element is the strongest? Br2 I2 Cl2 F2

F2

N=N-O and N=O=N are resonance structures to each other. True False

False

Since we can only see visible lines from a hydrogen lamp, hydrogen lamp does not produce any UV light. True False

False

Which of the following might be a contributing factor to low experimental purity of green crystals? Over-titration Forming the crystals too quickly by cooling it down in an ice-water bath Some green crystals are lost during filtration last week All of them will contribute to a low experimental %purity

Forming the crystals too quickly by cooling it down in an ice-water bath

Which of the following molecules has the smallest bond angle? BF3 NH3 CH4 H2O

H2O

A substance has a molar heat of solution of - 1000 kJ/mol. What is correct if 0.5 mol of this substance is dissolved in water? If only considering the heat exchange within the solution, the resulted solution will have a higher temperature. 500 kJ of heat will be released by the substance 1000 kJ of heat will be absorbed by the solvent. 500 kJ of heat will be absorbed by the substance

If only considering the heat exchange within the solution, the resulted solution will have a higher temperature. 500 kJ of heat will be released by the substance

In y=kx + b, x is y-intercept dependent variable indepedent variable slope

Independent Variable

Predict products of the following reaction: Cl2 + KI --> KCl +I- KCl + I2 ICl + K+ ICl + K

KCl + I2

When forming [Fe(C2O4)3]3- complex in coordination compound lab, oxalate ions are donating lone pairs to central metal Fe3+ to form coordinate bonds. In this process Fe3+ is serving as: Lewis base Lewis acid catalyst ligand

Lewis acid

What is/are the spectator ion(s) for the following chemical reaction? Check all that apply. Pb(NO3)2(aq) + Na2S(aq) --> PbS(s) + 2 NaNO3(aq) Pb2+ ion NO3- ion Na+ ion S2- ion

NO3- ion Na+ ion

NaClO is commonly used as bleach. The following is a sample reaction of NaClO. What is the oxidizing agent in this reaction?

NaClO

Draw the best Lewis structure of nitrate ion first and consider resonance structures if there are any. Which one is correct about the bonds in nitrate ion? There is two single bonds and one double bond One bond will be shorter than the other two All the statements are correct None of the statements are correct One bond is stronger than the other two

None of the statements are correct

When colorless NaOH solution is mixed with colorless HCl solution, what will happen? Bubbling Color change Precipitation Nothing obvious will happen, though there is a chemical reaction

Nothing obvious will happen, though there is a chemical reaction

When weighing a beaker, students should use either paper towel or wipes to hold beaker instead of using bare hand. Why?

Oil and salt from fingers may add a smalll mass to the beaker.

Ideal Gas Law states that PV=nRT. Which of the following pairs do NOT have a direct proportionality? V and T when P and n are kept constant P and T when V and n are kept constant P and n when V and T are kept constant P and V when n and T are kept constant V and n when P and T are kept constant

P and V when n and T are kept constant

Red and purple are two lines of hydrogen lamp. Which one is correct when comparing these two lines? Choose all that apply. Red line has smaller energy than the purple one. Red line has longer wavelengthh than the purple one. Red line has higher frequency than the purple one. The light of red line travels faster than the purple one.

Red line has smaller energy than the purple one. Red line has longer wavelengthh than the purple one.

Which of the following are correct about nodal planes in molecular orbitals? There may have more than one correct answers. Regardless it is sigma or pi, the antibonding molecular orbitals always have a nodal plane that is perpendicular to the internuclear axis Since 1s orbitals do not have any node, the sigma 1s antibonding orbitals cannot have any node Both bonding and antibonding molecular orbitals may have nodal planes. In sigma 2p bonding molecular orbital, there are no nodal planes.

Since 1s orbitals do not have any node, the sigma 1s antibonding orbitals cannot have any node Both bonding and antibonding molecular orbitals may have nodal planes.

During titration, it is very common to have some NaOH spilled to the inside wall of Erlenmeyer flask. Ideally, these spilled NaOH should be washed down, but most students (if not all) did not do so. How will these NaOH on the wall affect the experimental result?

Since these spills will make the volume of NaOH artificially higher, it will make the experimental result higher as well.

X g of hot water at 80 C is mixed with Y g cold water at 20 C in a perfect calorimeter. If X > Y, which of the following is true for the final temperature of water? Assume heat exchange is only between water samples. The final temperature will be exactly 50 C, which is the average of 80 and 20 The final temperature will be closer to 20 than to 80 The final temperature will be closer to 80 than to 20

The final temperature will be closer to 80 than to 20

Which one is correct about the reaction between cyanide ion and hydrogen ion? There are two correct answers for this problem. The chance for adding hydrogen ion to C is the same as adding it to N because both of them have lone pairs to accept H. The hydrogen ion will be added to N because N is more electronegative The hydrogen ion will be added to C because by doing so we will have a more stable product. The hydrogen ion will be added to C because C bears more negative charges.

The hydrogen ion will be added to C because by doing so we will have a more stable product. The hydrogen ion will be added to C because C bears more negative charges.

In part IIA, a student unknowingly spilled a few drops of HCl solution. How will the spill affect the molar heat of neutralization? The molar heat of neutralization will be lower than what it should be. The molar heat of neutralization will be higher than what it should be. Since HCl is the limiting reactant, small amount of spills will not affect the result

The molar heat of neutralization will be lower than what it should be.

If, instead of using 10 mL as instructed in the lab manual, a student knowingly used 20-mL aliquot in Chemical measurement and used 20 mL as volume for all subsequent calculations, how will the experimental result be affected?

This change should not affect the measured water density

What is the purpose of ammonium acetate when complexing Fe with o-phenanthroline in the digested cereal sample? To reduce the concentration of H+ because H+ may hinder the complexation reaction It absorbs some light Fe does not. To get rid of some other ions in the cereal sample ammonium acetate helps the complexed Fe to dissolve better

To reduce the concentration of H+ because H+ may hinder the complexation reaction

Which of the following is directly proportional to the concentration of a solution sample? intensity of light passing through transmittance of light absorbance of light extinct coefficient

absorbance of light

Which one is correct about the reaction yield of K3[Fe(C2O4)3]*3H2O? The theoretical yield must be calculated through stoichiometry. The mass of green crystal collected is the actual yield. all of them are correct. Percent yield is the fraction of theoretical yield that was actually obtained, or %Y = (actual Y) / (theoretical Y) * 100%

all of them are correct

Predict the molecular shape of SF2. trigonal planar tetrahedral bent linear

bent

Resonance structures lower the energy through orbital hybridization electron delocalization altering the overall molecular geometry forming more bonds

electron delocalization

Acid rain may damage statues partially due to the following reaction: 2 H+ + CaCO3 --> Ca2+ + CO2 + H2O What is the primary driving force of the reaction? Formation of gas Neutralization Precipitation Formation of a weak electrolyte

formation of gas

Which of the following has the largest repulsion, assuming that all the angles between electron pairs are identical? lone pair to lone pair They are all the same because they all contain the same number of electrons bonding pair to bonding pair lone pair to bonding pair

lone pair to lone pair

When Absorbance (unitless) is plotted on y-axis and Concentration (mg/mL) is plotted on x-axis, what is the unit of the slope mL mL/mg unitless mg/mL mg

mL/mg

Which of the following transition in a hydrogen atom will end up releasing the highest amount of energy? n = 10 to n = 3 n = 10 to n = 10000 n = 1 to n = 2 n = 3 to n = 2

n = 3 to n = 2

Which of the following transitions of the only electron in hydrogen atom will emit longest wavelength photon? n=100 to n=5 n=4 to n=2 n =2 to n=1 n=10 to n=20

n=100 to n=5

VSEPR Theory also applies to coordination complex. The only difference is that the central metal, as cation and electron deficient, never have lone pairs. So using VSEPR Theory, what is the molecular geometry of the complex of the green compound synthesized? octhedral trigonal planar tetrahedral trigonal bipyramidal

octahedral

The coordination compound lab is a two-week lab. During the second week of this lab (after we complete Computational Modeling lab) , we will use KMnO4 to titrate oxalate ion and then use the titration data to calculate the %purity of the coordination compound being synthesized. In this titration reaction between MnO4- and C2O42-, what is the oxidizing agent? H ion Mn^2+ ion permangnate ion oxalate ion carbon dioxide

permanganate ion

A beaker of NaOH solution is mixed with another beaker of CuCl2 solution. If there is a chemical reaction occurring, what is the driving force for the chemical reaction? Neutralization Formation of gas Precipitation There is actually no reaction will occur.

precipitation

Assume that multiple trials were made. How closely the results of these trials are to each other is called: standard deviation R square accuracy precision

precision

The coordination compound being synthesized is green in color. What color of light does this compound absorb the strongest? violet blue green red orange

red

In reaction below, what states of matter should the products have? Ba(NO3)2 + H2SO4 --> BaSO4 + 2 HNO3 s for BaSO4 and aq for HNO3 aq for BaSO4 and g for HNO3 aq for both products. s for both products.

s for BaSO4 and aq for HNO3

What is the hybridization of S atom in SF4? sp sp3d2 sp2 sp3d sp3

sp3d

Check all categories of strong electrolyte. Strong acids weak bases alcoholes Soluble ionic compounds

strong acids soluble ionic compounds

What is the electron geometry of H2O molecule? linear square plannar trigonal planar bent tetrahedral

tetrehedral

When intensity of light changes due to sample absorption, which of the following change accordingly? wavelength frenqency energy of each photon transmittance

transmittance

What is the molecular geometry of carbonate ion, CO32-? tetrahedral trigonal planar trigonal pyramidal bent

trigonal planar

FeC2O4 is insoluble in water. What color is FeC2O4(s)? green red brown white yellow

yellow