Molecules & Compounds

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15. Give the total number of atoms of each element in one formula unit of each of the
     following compounds:
   

Compound Number of Each Type of Element
CaC2O4
C6H5CHCH2
CuCO3(OH)2
Pt(NH3)2Cl2
K4Fe(CN)6

 

19. Predict the charges on the ions formed by aluminum and selenium.
    

23. Give the symbols, including the correct charge, for each of the following ions:

Ions Charge
Strontium ion
Aluminum ion
Sulfide ion
Cobalt(II) ion
Titanium(IV) ion
Hydrogen carbonate ion
Perchlorate ion
Ammonium ion

25. For each of the following compounds, give the formula, charge, and number of each
     ion that makes up the compound:

Compound Formula, Charge, number of ions present
K2S
NiSO4
(NH4)3PO4
Ca(ClO)2
KMnO4

31. Solid magnesium oxide melts at 2800 oC. This property combined with the fact that it
     is not an electrical conductor, makes it an ideal heat insulator for electric wires in
     cooking ovens and toasters (see the photo). In contrast, solid NaCl melts at the relatively
     low temperature of 801 oC. What is the formula for magnesium oxide? Suggest a reason
     for its melting point being so much higher than that of NaCl.

33. Name each of the following ionic compounds:

Ionic Compound Name
K2S
NiSO4
(NH4)3PO4
Ca(ClO)2

35. Give the formula for each of the following ionic compounds:

Name Formula
Ammonium carbonate
Calcium iodide
Aluminum phosphate
Copper(II) Bromide
Siver(I) acetate

43. Calculate the molar mass for each of the following compounds.

Compound Molar Mass
Iron(II) oxide
Boron trifluoried
Manganese(II) chloride tetrahydrate

47. Acrylonitrile, C2H3CN, is used to make acrylic plastics. If you have 2.50 kg of
     acrylonitrile, how many moles of the compound will you have?

    

55. Vinyl chloride, CH2CHCl, is the basis of many important plastics (PVC) and fibers.
     (a) Calculate the molar mass
     (b) Calculate the mass percent of each element in the compound
     (c) How many grams of carbon are there in a 454 g sample of vinyl
          chloride?

59. Acetylene is a colorless gas that is used as a fuel in welding (just ask Bobby Z)
     torches, among other things. It is 92.26% C and 7.74% H. Its molar mass is
     26.02 g/mol. Calculate the empirical and molecular formulas for this compound.

     

97 Transition metals can combine with carbon monoxide (CO) to form compounds such
     as Fe(CO)5, and Co(CO)8. Assume  that you combine 0.125 g of nickel with CO and
     isolate 0.364 g of Ni(CO)x. What is the value of x?

    

112. When analyzed, an unknown substance gave these experimental results: C, 54.0%,
       H, 6.00%, and O, 40.0%. Four different students used these values to calculate the
      empirical formulas given below.
        (a) C4H5O2        (c) C7H10O4
        (b) C5H7O3        (d) C9H12O5

        Which answer is correct? Why did some students not get the correct answer?