18. One mole of CH₄ is burned completely with 20 moles of air.

What is the stack (flue) gas composition?

(Assume air is 21 mole% O₂, 79% N₂)

Somehow the answer to this is (4) but I dont see how that is possible so please EXPLAIN.

Which of the following statements relating to molecular orbital theory (MO) is incorrect?

(1) Combination of two atomic orbitals produces two molecular orbitals

(2) Combination of two 2p orbitals may result in either sigma or pi MOs

(3) A species with a bond order of zero will not be stable.

(4) Molecular orbitals are hybridizations of atomic orbitals.

(5) A diatomic molecule with an odd number of electrons will be paramagnetic

Determine the pH during the titration of 66.6 mL of 0.457 M acetic acid (Ka = 1.8×10-5) by 0.457 M KOH at the following points. (Assume the titration is done at 25 °C.)

a.) Before the addition of any KOH

b.)  After the addition of 16.0 mL of KOH

c.) At the half-equivalence point (the titration midpoint)

d.) At the equivalence point

e.) After the addition of 99.9 mL of KOH

Thank you!!

Quinine (C20H24N2O2) a white crystalline bitter tasting powder which was originally used as a preventative medication for malaria. It is a weak base with kb=3.3 x 10^-6 M. However, Quinine is now more commonly used in small concentrations in tonic water. Quinine is responsible for the fluorescent properties when tonic water is under ultraviolet light (blacklights). Due to the toxic effects of quinine the United States limits the quinine content to 83 ppm for each 1 liter bottle.

Write a balanced chemical equation of quinine solid dissolving in water including all phases, and indicate which species is an acid, base, conjugate acid and conjugate base.

Calculate the pH of the tonic water.

1. Write the half reactions that occur at the anode and cathode in these electrochemical cells. Annotate which half reaction occurs at the anode and the cathode.

2. Write the overall balance reaction for the following electrochemical cells.

Ag(s), Ag(NO3)2 (1.0 M) || Cu (s), CuCl2 (1.0M)

Zn(s), Zn(NO3)2 (1.0M) || Ni (s), Ni(NO3)2 (1.0M)

Zn(s), Zn(NO3)2 (0.3 M) || Cu(s), CuCl2 (0.5M)

Ag(s), Ag(NO3)2 (0.3 M) || Cu(s), CuCl2 (0.5 M)

Ag(s), Ag(NO3)2 (0.3 M) || Ni(s), Ni(NO3)2 (0.5 M)

Cu(s), CuCl2 (.001 M) || Cu(s), CuCl2 (1.0 M)

Thank you!!!

Balance the following oxidation-reduction reactions, and show ALL steps:

1. MnO4- + Cl- <--> Mn2+ + Cl2

2. As2S3 + NO3- <--> HAsO3 + S + NO

Balance the ffollowing redox reactions and show ALL steps:

1. Fe3S4 + O2(g) <--> Fe(OH)3(s) + SO42-

2. FeS2(s) + NP3- <--> N2(g) + FeOOH(s) + SO42-

Professor Solomon tells her class, "Neurocognitive disorders are diagnosed through a process of elimination. Neurocognitive disorders may be due to a specific medical condition, a substance-induced condition, or may result from multiple etiologies. The category of neurocognitive disorders is arbitrary because other mental disorders may be associated with neurocognitive disorders and organic involvement. It is always difficult to measure, assess, and determine the causes of neurocognitive disorders." Which part of Professor Solomon's statement is accurate?​

A hydrocarbon with the general formula C_xH_y is 92.26% carbon. Experiment shows that 0.311 g hydrocarbon fills a 185 mL flask at 88.7 °C with a pressure of 486 mm Hg.

Calculate the molecular formula for this compound.

When solid sodium bisulfate is added to a solution of sodium bisulfate and thymol blue indicator, which way would the equilibrium shift?

Shift toward the reactants

Shift toward the products

No shift as it is in equilibrium

None of the above

Is the disassociation of magnesium hydroxide to magnesium ion and the hydroxide ion exothermic or endothermic?

exothermic

endothermic

need more information

heat was neither absorbed nor released

Which way would the equilibrium shift when hydrochloric acid is added to mixutre that contains sodium hydroxide, phenolphthalein, and magnesium chloride?

Shift toward the reactants

Shift toward the products

No shift as it is in equilibrium

None of the above

If heat is absorbed during the course of a reaction that reaction is said to be endothermic. In an endothermic reaction heat is a?

Product

Reactant

Neither

Both

Why are allenes important in Organic Chemistry?

What is a Mannich Type Reaction? Please show an example of this.

Solutions of sodium carbonate and silver nitrate react to form solid silver carbonate and a solution of sodium nitrate. A solution containing 7.00 g of sodium carbonate is mixed with one containing 4.75 g of silver nitrate. After the reaction is complete, the solutions are evaporated to dryness, leaving a mixture of salts. How many grams of each of the following compounds are present after the reaction is complete?

sodium carbonate

silver nitrate

silver carbonate

sodium nitrate

If (S)-Ibuprofen is more active pharmacologically, why are Ibuprofen prescriptions still prepared from a racemic mixture of the enantiomers?

4. Forty-three milliliters of 0.130 M nitric acid is added to 30.0 mL of 0.095 M calcium hydroxide. Calculate the pH of the initial nitric acid solution and then calculate the pH of the combined solutions. Assume the solution volumes are additive. Hint: determine whether excess H+ or OH- remain in solution after neutralization, then calculate the pH.

Show all steps please to help me understand, thank you!

I don't understand the Van't Hoff factor..
I feel dumb because I don't understand it