For the production of ammonia from its elements, 3H2(g)+N2(g)→2NH3(g),
ΔH = -21.9 kcal.

Part A: Is this process endothermic or exothermic?   

Part B: How many kilocalories are involved in the production of 27.75 g of NH3?

Part C: How many kilocalories are involved if 26.90 g of H2 are consumed in this reaction?

What are the 4 major macromolecules and how to they support life.Be sure to check your spelling. Minimum response should be 10 sentences.

a)How many mol are in 64.61 g of nickel(II) phosphite?

b)How many mol of carbon are in 30.6 g of aluminum carbonate?

c)What is the mass (in grams) of 1.01 mol of iron(III) chloride?

d)What is the mass of oxygen in 5.71 g of aluminum oxide?

what new facts you discover about the nature of matter and/or what surprise you in the experiment called the molecular models: lewis dot formula, VSEPR theory, and valence bond theory

if youre doing an analysis with a tlc plate and you use ethyl actete (polar) as the solvent please rank the distance that these molecules would move (aka which one would be the highest on the plate). They are the same molecule, the only thing that changes is the functional group. One has an alcohol functional group, one has a ketone, and the other has alkene functional group

If the Ksp of PbI₂ is 7.1 X 10^-9, will precipitation occur when 10 mL of 1.0 X 10^-4 M Pb(NO₃)₂ is mixed with 10 mL of 1.0X10^-3 M KI?

Will precipitation occur when 10mL of 1.0X 10^-2 M Pb(NO₃)₂ added to 10mL of 2.0 X 10^-2 M KI?

*Please show step-by-step, as I am really lost. Thank you in advance.

a) Which electrons experience a greater Z_eff (effective nuclear charge): the valence electrons in Be or the valence electrons of N? Why?

Using the simple equation on page 260, calculate the Z_eff of 3p electron of K atom.

a. Using the trends in ionization energy of sodium and electron affinity of oxygen, explain why sodium oxide has the formula Na₂O and not NaO.

Which specific orbital loses an electron in the fourth ionization step of Carbon?

2) Write the atomic radii and ionic radii of the following using the interactive Periodic   
Table on the web (Link: http://www.chemeddl.org/resources/ptl/index.php).

a-    Explain the trend in the radii for two elements in the same group and that for two      
     elements in the same period. Be sure to include units.

                                                Atomic Radius                                   Ionic Radius

            a. Ra             

        b. Cd

    c. Sr

4)Briefly explain why valence electrons are more important than core electrons in determining the reactivity and bonding in atoms.

Write the abbreviated electron configuration for the following pairs:

   a-Ir (Iridium) atom
   b- Ir³⁺      
   c- Se atom
d- Se^2—

How many unpaired electrons are there in the following: ( you should do their condensed electron configurations first)

a-Fe atom

b-Cu¹⁺ ion

In Michaelis-Menten kinetics, what values would make an enzyme “good” at catalysis?

The complex ion Cu(NH3)42 is formed in a solution made of 0.0200 M Cu(NO3)2 and 0.400 M NH3. What are the concentrations of Cu2 , NH3, and Cu(NH3)42 at equilibrium? The formation constant*, Kf, of Cu(NH3)42 is 1.70 × 1013.

In this week's experiment, the heat of vaporization of liquid nitrogen is determined by measuring the change in temperature of a known sample of warm water when liquid nitrogen is added.

In one experiment, the mass of water is 104 grams, the initial temperature of the water is 69.3^oC, the mass of liquid nitrogen added to the water is 60.6 grams, and the final temperature of the water, after the liquid nitrogen has vaporized, is 41.3^oC.

Specific heat of water = 4.184 J K^-1g^-1

How much heat is lost by the warm water?

Heat lost =         J

What is the heat of vaporization of nitrogen in J g^-1?

Heat of vaporization =           J g^-1

What is the molar heat of vaporization of nitrogen?

Molar heat of vaporization =             J mol^-1

Trouton's constant is the ratio of the enthalpy (heat) of vaporization of a substance to its boiling point (in K). The constant is actually equal to the entropy change for the vaporization process and is most often a measure of the entropy in the liquid state. The value of the constant usually lies within the range 70 to 90 J K^-1mol^-1, with a value toward the lower end indicating high entropy in the liquid state.

The normal boiling point of liquid nitrogen is -196^oC. Based upon your results above, what is the value of Trouton's constant?

Trouton's constant =           J K^-1mol^-1

State (2), explain (2), and derive (6) Gibbs’ Phase rule for a system with C components occurring in P different phases.

160 g of a 0.80% sodium hydroxide solution.

The following question involves the reaction of sodium hydroxide and succinic acid. Succinic acid is diprotic: the acid (H₂C₄H₄O₄) reacts with two of its hydrogens to give C₄H₄O₄^2-. The balanced “molecular” equation for the reaction has coefficients of 2 for NaOH and 1 for succinic acid:

2 NaOH (aq) + H₂C₄H₄O₄ (aq) --> Na₂C₄H₄O₄ (aq) + 2 H₂O (l)

A student weighs 1.700 g of succinic acid and dissolves it in water in a 250.0 mL volumetric flask. A 25.00 mL sample of this solution is withdrawn and placed in a 125 mL Erlenmeyer flask, to which 5 drops of the acid-base indicator phenolphthalein is added. This solution is titrated with a sodium hydroxide solution of unknown molarity in a buret.

a) How many moles of succinic acid were weighed and dissolved in the volumetric flask?

0.0572 M

b) How many moles of succinic acid were placed in the Erlenmeyer flask?

1.43 x 10^-3 mol

c) If the unknown sodium hydroxide solution was known to be approximately 0.20 M, at approximately what buret volume would you expect the end point of the titration? Show the calculation, including the use of the appropriate coefficients, as a 2 significant figure estimate:

14.30 mL NaOH

d) If the measured volume at the end point was 13.32 mL of sodium hydroxide added, calculate the actual molarity of the sodium hydroxide solution.

0.214 M NaOH

You are going to standardize a 0.80% solution of sodium hydroxide solution for which the molarity is approximately 0.20 M. You will have dry succinic acid, a 250 mL volumetric flask, a 25.00 mL pipet, a 50.00 mL buret, a phenolphthalein indicator solution, and other standard laboratory equipment. For each titration you will withdraw a 25.00 mL sample of the succinic acid solution with a volumetric pipet. Therefore, you will deliver exactly one-tenth of your initial mass of succinic acid (to four significant figures) in each titration. In deciding the amount of succinic acid to weigh, assume that you will be using approximately 15 mL of the sodium hydroxide of approximate 0.20 M concentration for each titration, and you need enough succinic acid for ten titrations. Show how to calculate the mass of succinic acid you will need to weigh.

2. Calculate the gravimetric factor for the following: (a) Cr2O3 in Ag2CrO4 (b) CaO in CaCO3,

3.Describe briefly the mechanism of precipitate formation.

So, I have some questions about the analytical chemistry experiment "Titrations based on complex formation."
1- Can you determine Mg by displacement or back titration?
2- You need to know the amount of EDTA added to solution in back titration method but you do not need to know the amount of MgEDTA added in displacement titration. Why? Explain by giving related reactions.
3- What is the minimum pH value needed for satisfactory titrations of Ca+2 and Mg+2 cations with EDTA?

Thanks for your help.