A chemist weighed out 1.654 g of a mixture containing unknown amounts of iron (Fe) and lead (Pb) and placed the sample in a 0.500 L flask containing O2 (g) at 24.0 C and 846 torr. After heating, the reaction to form Fe2O3(s) and PbO2(s) was completed, the vessel was cooled to 24.0 C and the pressure of O2 (g) remaining was 452 torr. Calculate the mass percentage of lead in the mixture. Molar masses (g/mol) : PbO2: 239.20; Fe2O3: 159.69; Pb: 207.20; Fe: 55.85

When exposed to air, aluminum metal, Al, reacts with oxygen, O2, to produce a protective coating of aluminum oxide, Al2O3, which prevents the aluminum from rusting underneath. The balanced reaction is shown here: 4Al+3O2→2Al2O3

What is the theoretical yield of aluminum oxide if 2.20 mol of aluminum metal is exposed to 1.95 mol of oxygen?

For the diprotic weak acid H2A, Ka1 = 2.8

The C₅H₅⁺ and C₅Cl₅⁺ cations, which have never been isolated, are known to be ground state triplets - that is, they have 2 unpaired electrons, thus are diradicals. But the C₅(CH₃)₅⁺ cation has no unpaired electrons - it is a singlet.

Construct a schematic molecular diagram of C₅H₅⁺ (pi system only) in D₅h point group using p_z-orbitals of C. Sketch the shape of each orbital next to the irreducible representation of the MO. Does your MO diagram support the singlet or triplet ground state?

Result from X-ray crystallography, NMR, and theory..... C₅(CH₃)₅⁺ is an irregular pentagon.... the ring is nonplanar... the pi electrons are found to be largely localized on opposite sides of the ring - in an allyl cation fragment and in a double bond.

Now, construct a schematic molecular diagram of C₅(CH₃)₅⁺ (pi system only) using p_x-orbitals of C, assuming allyl group and a double bond separately and simply put them on the same stack). Sketch the shape of each orbital next to the irreducible representation of the MO. Does your MO diagram support the singlet or triplet ground state?

Please help!! Super hard homework question!

Questions

Which fuel was more efficient (produced more calories per gram)? Explain your answer. Fuel canister: (diethylene glycol) or Tea candle: (paraffin) ?

Explain the difference in the efficiencies of the fuels you tested based on the chemical structures of the fuels.

Conduct research on both diethylene glycol and paraffin wax; for each fuel, summarize in your own words in one or two sentences how these fuels are synthesized. Cite the sources that you use for your research.

What are the possible sources of error in this experiment? How could the errors be reduced in future experiments?

1. When 4.203g of NaOH is added to 100.0mL of water, the temperature of the solution increases by 3.0C. Assume the density of the solution to be 1g/mL and the specific heat of capacity of the solution to be 4.184 J/gK.

a) Calculate the amount of heat absorbed by the solution.

b) Find the enthalpy change for the dissolution of NaOH.

c) Find the enthalpy change per mole of NaOH.

You prepare a buffer solution from 10.0 mL of 0.100 M MOPS (3-morpholinopropane-1-sulfonic acid) and 10.0 mL of 0.084 M NaOH. Next, you add 1.00 mL of 4.69 × 10-6 M lidocaine to this mixture Denoting lidocaine as L, calculate the fraction of lidocaine present in the form LH .
The Ka of MOPS is 6.3 e-8, and the Kb of lidocaine is 8.7e-7

Simultaneous equilibria.

write the equations for the processes involving or affecting the solubility of Ca(OH)₂ (s).

i. The solubility of the salt, itself: (K_sp = 6.5 x 10⁻⁶)

ii. The autoprotolysis of water and its K_w:

iii. The formation of an ion pair between Ca²⁺ and OH⁻. K_{ion pair} = 1.3

iv. The Charge Balance equation

v. A Mass balance equation:

Simplify the simultaneous equations to an expression in a single unknown. Show your work.

calculate the equilibrium concentrations of all species, and indicate the values here:

Find the concentration of Fe⁺³ and NCS^- in the following vials:

Vial # .002 M Fe(NO₃)₃ .002 M KSCN Distiled Water

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1 3 mL 1 mL 6 mL

2 3 mL 2 mL 5 mL

3 3 mL 3 mL 4 mL

Find [H+] in 0.40 M NH₄NO₃ at 25 degrees Celsius given that K_b = 1.8 x 10^-5 for NH₃ (aq).

How/why does the chemical species F- (fluoride) at concentrations 3.22 ppm cause fish death? Explain your answer in a typed paragraph.

what is the concentration of H+ ions after adding 5.41 mL of of 0.816 M NaOH to 65.7 mL of 1.97 M HNO3?

Part B

Indicate the number of unpaired electrons for following: [noble gas]ns2np5

Express your answer as an integer.

Part C

Identify the group of elements that corresponds to the following generalized electron configuration: [noble gas]ns2(n?1)d2

Incorrect; Try Again; 5 attempts remaining

Part D

Indicate the number of unpaired electrons for following: [noble gas]ns2(n?1)d2

Express your answer as an integer.

Part E

Identify the group of elements that corresponds to the following generalized electron configuration: [noble gas]ns2(n?1)d10np1

Incorrect; Try Again; 5 attempts remaining

Part F

Indicate the number of unpaired electrons for following: [noble gas]ns2(n?1)d10np1

Express your answer as an integer.

Part G

Identify the elements that correspond to the following generalized electron configuration: [noble gas]ns2(n?2)f6

Express your answer as the element symbol. If there is more than one answer, separate them by a comma.

Part H

Indicate the number of unpaired electrons for following: [noble gas]ns2(n?2)f6

Express your answer as an integer

chemistry

please I need report for lap experiment :

1- testing salt for cations
2- testing salt for anions
3- titration

hint:
please send copy to my email
[email protected]