For analysis of a calcium sample, it is desirable to obtain a precipitate weighingabout 0.50g. What size sample should be taken from a mixture which isapproximately 56% CaO?

The following are some calculation questions related to the experiment. Please include the questions and their answers in your report:

a) A 0.05 L solution of 0.5 mol/L NaOH was titrated until neutralized into a 0.025 L sample of HCl. What was the concentration of the HCl?

b) 50 L of 2.0 mol/L Hydrochloric acid is titrated with sodium hydroxide to form water and sodium chloride. How many moles of sodium hydroxide are consumed in this reaction?

c) 100 L of 5 mol/L NaOH are required to fully titrate a 50 L solution of HCl. What is the initial concentration of the acid?

A) Consider the reaction
2N₂(g) + O₂(g) ---> 2N₂O(g)
Using the standard thermodynamic data in the tables linked above, calculate deltaG_rxn for this reaction at 298.15K if the pressure of each gas is 35.48 mm Hg.
______ kJ/mol

B) Consider the reaction
CH₄(g) + H₂O(g) ---> 3H₂(g) + CO(g)
Using the standard thermodynamic data in the tables linked above, calculate deltaG for this reaction at 298.15K if the pressure of each gas is 12.05 mm Hg.

______ kJ/mol

C) Consider the reaction

2N₂(g) + O₂(g) -----> 2N₂O(g)
Use the standard thermodynamic data in the tables linked above. Calculate deltaG for this reaction at 298.15K if the pressure of N₂O(g) is reduced to 10.45 mm Hg, while the pressures of N₂(g) and O₂(g) remain at 1 atm.
______ kJ/mol

The titration process is used to analyze the content of some food product. Let's say you are analyzing the concentration of acetic acid in the vinegar. Answer the following question:

• What would you categorize the vinegar, an acid or a base?

You have 5 mL of vinegar in a flask and 2 drops of phenolphthalein indicator. You titrate exactly 36.9 mL of 0.1 mol/L NaOH from a burette directly into the flask which gives you a pale pink color. This means the solution has reached neutralization.

• Calculate n of the NaOH.

• Calculate c of the vinegar in mol/L.

• Depending on your answer for the previous question complete the following sentence:

one liter of vinegar contains …………………………. mol of acetic acid.

Draw the molecular orbital diagram for the valence electrons in H2O. Using the electron configuration and the Walsh correlation diagram, explain why H2O is bent and not linear.

The chief compound in marble is CaCO3. However, marble is readily attacked by acids.

[Ca2+] in normal rainwater of pH 5.0 = 0.024 M

a) Determine the molar solubility of marble (that is, [Ca2+] in a saturated solution).

b) Determine the equilibrium constant for the overall reaction that occurs when marble reacts with acid

CaCO3 (s) + H3O+ ↔ Ca2+ (aq) + HCO3- (aq) + H2O (l)

My problem is that I have been given no more information other than what is written above. I'm not sure how to go about solving it with this amount of information.

5. How many kJ of energy are required to change 1.00 m^3 of pure water by 1.0*C? Assume a perfect system. The specific heat of the water is 4.184 J/g*C. The density of water is 1.000 g/mL.

6. 2.500 grams of metal X (molar mass 65.39 g/mole) was reacted with 100.0 mL of a 1.500 M HCl solution in a coffee cup calorimeter. The temperature went from 12.50 *C to 40.50 *C. Determine the reaction enthalpy per mole of metal X. The specific heat of the solution is 4.184 J/ g*C. Assume a solution density of 1.00 g/mL and a perfect system.

7. 20.12 grams of butane, C4H10, was combusted with oxygen in a bomb calorimeter. The temperature of .500 kg of water went from 5.00 *C to 25.89 *C. The specific heat of the water is 4.184 J/g*C. Assume a solution density of 1.00 g/mL. Determine the heat (kJ) evolved per mole of butane. Assume a perfect bomb calorimeter.

Dinitrogen Pentoxide (N2O5) decomposes in chloroform as a solvent to yield NO2 and O2. The decomposition is first order with a rate constatnt at 50 degrees Celcius 1.75 x 10^{-5 s-1}. Calculate the partial pressure of O2 produce from 1.00L of 0.500 M N2O5 solution at 50 degrees celcius over a period of 18.0 hours if the gas collected in a 10.0L container. (Assume that the products do not dissolve in chloroform.)

he decomposition of ozone in the upper atmosphere is facilitated by NO. The overall reaction and the rate law are O3(g)+O(g)→2O2(g) Rate=k[O3][NO] Write a mechanism that is consistent with the rate law.

What is the pH of a 0.136 M monoprotic acid whose Ka is 5.7 10-4?

3. Consider the following possible ligands. For which of these do you expect back-bonding to be significant in their complexes? For those that you do not expect to participate in back-bonding, explain why.

H2       CO       Br2       O2       NO

A liter of pH 7.20 phosphate buffer is needed for a certain experiment. The Henderson-Hasselbach equation will be sufficiently accurate for your determination of pH. The pK’s for possibly relevant phosphate species are:

H3PO4 ↔ H2PO4- + H+ pK = 2.15

H2PO4- ↔ HPO4-2 + H+ pK = 7.20

HPO4-2 ↔ PO4-3 + H+ pK = 12.4

0.100 Moles of H3PO4 were dissolved in about 800 mL of water, and the pH was adjusted to 7.20 using a standardized pH meter and a 1 M solution of KOH followed by addition of water to a volume of 1.00 L.

a. (10 pts) Write the equation for the charge balance to show how [K+], [H2PO4-], and [HPO4-2] are related. ([H+] and [OH-], although they are charged species, can be neglected for charge balance when compared to [K+], [H2PO4-], and [HPO4-2])

b. (10 pts) At pH 7.20 what is the ratio of [H2PO4-] to [HPO4-2]?

c. (20 pts) Combine your findings from parts a and b to determine how many mL of 1 M KOH must be added. {An important hint: By mass balance, the total molar concentration of phosphate species at pH 7.2 must equal the total molar concentration of phosphate species that was added from H3PO4.}

PLEASE ANSWER ALL PARTS, I NEED HELP. THANKS IN ADVANCE!

I have to estimate, to the nearest degree, the temp. at which the vapor pressure of a solution (3.9g benzene, 4.6g toluene) reaches 1 atm. I believe the mole fractions are .73 for benzene, and .26 for toluene.