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Empirical and Molecular Formula for various substances

Submitted by mwolde on Mon, 05/26/2008 - 03:30

1.A compound containing titanium (Ti) and Chlorine is analyzed by converting all the titanium into 1.20 g of TiO2 and all the chlorine into 6.45 of AgCl. What is the simplest formula for the original compound?

2.Estrone is a female sex hormone that is known to contain 80.0% carbon, 8.2% hydrogen, and the remainder of oxygen. If 793 mL of estrone is found to have a mass of 4.97 g at 0.90 atm and 200 C, find the molecular formula for estrone.

3.Farmers use fertilizers mainly to replace depleted nutrients in the soil. Liquid ammonia and ammonium nitrate are two substances that are used to replace essential nitrogen in the soil. Based on the percentage of nitrogen by masss, which of these two chemicals would be the better fertilizer? Assume that the cost per kilogram of each chemical is about the same.


Problem 1: Find the moles of TiO2 in 1.20g.  Moles of Ti must be the same as moles of TiO2.  Find the moles of AgCl.  Moles of Cl must be the same as moles of AgCl.  Find the simplest formula of the compound by dividing the moles of Ti and the moles of Cl by the smallest number of moles (most likely the moles of Ti).

Problem 2: Assume a 100g sample.  Find moles of each of the component elements.  Divide through by the smallest number of moles to find the empirical formula. 

Use the Ideal Gas Equation to find the moles of estrone.  Divide the number of grams of estrone by the number of moles found from the Ideal Gas equation to determine the Molecular Mass.

Find the empirical formula mass from the empirical formula and divide the Molecular Mass by the emp. formula mass to find how many emp. formula units are in a molecule.

Problem 3:  Determine the % composition of N in NH3 and NH4NO3.  Percent composition can be found using the formula:
                        percent of N = mass of N in formula / formula mass  x 100
Whichever formula has the higher % nitrogen would be the better fertilizer.


thanks so much... i really appreciate ur help.... i have done the solutions and was wondering if u could check it for me

13.
Mol of TiO2 =  Mol of Ti

Mol of TiO2 =  = 0.00508 mol

Mol of AgCl =  = 0.04479 mol

Ti =  = 1

Cl =  = 9

Simplest formula = TiCl9

14.
C= 80%    H= 8.2%      O= 11.8%

  moles of C =    = 6.7 mol

  moles of H =  = 8.1 mol

  moles of O =  = 0.7 mol

C =  = 9.5      H =  = 11.5      O =  = 1

C19H23O2

V= 793 mL = 0.793 L  P= 0.90 atm  T= 200°C = 473 K

n=  =  = 0.18388 mol

  1 mole has a mass of =  = 271.88 g/mol

Thus, (C19H23O2) x n = 271.88 g/mol

283 g/mol . n = 271.88 g/mol

N= 1

  the molecular formula  =  C19H23O2

15.
Molecular mass of NH3 = (14g+3g) = 17 g

Percent of N =  x 100 % = 82.35 %

Molecular mass of NH4NO3 = (14g + 4g +14g++48g) = 80 g

Percent of N =  x 100% = 17.5 %
Liquid ammonia (NH3) would be the better fertilizer.

mwolde wrote:

1.A compound containing titanium (Ti) and Chlorine is analyzed by converting all the titanium into 1.20 g of TiO2 and all the chlorine into 6.45 of AgCl. What is the simplest formula for the original compound?

2.Estrone is a female sex hormone that is known to contain 80.0% carbon, 8.2% hydrogen, and the remainder of oxygen. If 793 mL of estrone is found to have a mass of 4.97 g at 0.90 atm and 200 C, find the molecular formula for estrone.

3.Farmers use fertilizers mainly to replace depleted nutrients in the soil. Liquid ammonia and ammonium nitrate are two substances that are used to replace essential nitrogen in the soil. Based on the percentage of nitrogen by masss, which of these two chemicals would be the better fertilizer? Assume that the cost per kilogram of each chemical is about the same.