Butane, C4H10, reacts with oxygen, O2, to form water, H2O, and carbon dioxide, CO2, as shown in the following chemical equation:

2C4H10(g)+13O2(g)→10H2O(g)+8CO2(g)

a) Calculate the mass of water produced when 2.04 g of butane reacts with excess oxygen.

b) Calculate the mass of butane needed to produce 72.8 g of carbon dioxide.

I can't get this question. It doesn't make any sense.

In Elmo’s world, the study of chemistry is just beginning. It is a much simpler world with only a few elements. The Journal of the Elmo Chemical Society reports the following compounds have been created: Q₂E; QP; WX; WP₂; Z₂D; AV; and SX. Elmo has been unable to make any compounds with element T or with element G. Elmo has also determined the atomic masses of all the known elements.

Elmo and his friends now need your help in building a Periodic Table and suggesting new areas of research.

First, consider the data on atomic masses and on the compounds which have been made. (Since they are just beginning, some elements may not have been discovered yet.) Make a Periodic Table for Elmo’s world. Leave gaps where necessary for elements which are not yet discovered.

Second, explain to Elmo how the table you made is arranged.

Third, suggest the formula for compounds made from A and X, from S and E, from A and P, and from B and Z.

A hydrocarbon with general formula CxHy was burned completely in air, yielding .18g of water and .44 g of carbon dioxide. Which formula could give such data? Please explain step by step process. The answer is C2H4 and molar mass for water is 18. g/mol-1 and CO2 is 44.0 g / mol -1

2- Calculate the pH and fraction of dissociation of a 0.00753 M sodium hypochlorite solution (NaOCl) solution.

Determine the oxidation number of P in H3PO3, Mn in KMnO4, Mn in MnO2, N in Ca(NO3)2, O in H2O2.

Balance the following equation. Show each half-reaction and the final, overall reaction. Label the oxidizing agent, the reducing agent, the species that is oxidized and the species that is educed.

Fe2+ + Cr2O7 2- → Fe3+ + Cr3+ (acidic solution)

An octapeptide with the amino acids < Ile, Arg, Met, Phe, Pro, Thr, Tyr, Val > was subjected to digestion reactions A, B and C in order to deduce its amino acid sequence. The following results were obtained. The exact position occupied by each of the amino acids (positions 1-8 in the sequence) will be known when the results are analyzed

A. Digestion with Trypsin yielded a [Thr-Arg] dipeptide and a [hexapeptide] with the remaining amino acids.

Question (A1): Explain the reasoning for the fragmentation pattern
Question (A2): What can you deduce regarding the exact positions occupied by Thr and Arg in the

sequence?

B. Cyanogen bromide treatment of the octapeptide also yielded a dipeptide [Phe-Pro] and a hexapeptide. Question (B1): Explain the reasoning for the above fragmentation pattern

Question (B2): What can you deduce regarding the exact positions occupied by Phe and Pro in the sequence?

C. Chymotrypsin cleaved the octapeptide into two tetrapeptides, one with and the other

Question (C1): Explain the reasoning for the above pattern
Question (C2): What can you deduce regarding the exact positions occupied by Val and Ile in the

sequence?

Question (D): What is the sequence of the peptide?

How many moles of PCl5 can be produced from 28.0 g of P4 (and excess Cl2)?

Using MO diagram, explain why cycloctatetraene is very reactive.

What is the limiting reactant if 2.047 grams of NaOH (s) reacts with 101.3 mL of a 2.09 M HCl solution?

Calculate the nuclear binding energy in mega-electronvolts (MeV) per nucleon for 244Pu if its nuclear mass is 244.064 amu.

What is the difference between radicals and ions?

Mercury melts at 234K and boils at 298K at 2x10^-3 torr of pressure. Heat is added to a sample containing 3.00 kg of mercury (Hg) at 238K. The rate of heating is 2000 watts. The pressure is constant and you can assume table values are not affected by reduced pressure or temperature. At what time will the mercury start to boil? How much time for the mercury to completely boil? How long until the mercury gas heats up to 498K?

2)

a) Describe in your own words and terms where the origin of the activation barrier comes from and what it represents in a chemical reaction. b) Given the same thermodynamic factors, consider the reaction of two small molecules or two large molecules with one another. Which pair should have the higher activation energy? Why?