Chemistry Calculations: Finding Moles, Mass, and Number of Particles

Calculations:

SHOW WORK on separate paper and copy final answers in the boxes provided. Use correct number of significant figures and report units with answers where required.

1.Find the number of moles in 25.0 grams of each of the following:

    a.    Ni            b.    C6H6            c.    Ca(OH)2

2.Find the mass of 0.750 moles of each of the following:

    a.    Br2            b.    P4O10            c.    Cu2S

3.Find the number of particles in 35.0 grams of each of the following:
    a.    Ag            b.    CF4            c.    C6H12O6

4.Find the mass of 4.52 x 1023 particles of each of the following:
    a.    N2            b.    Li3N            c.    H2SO4

5.Determine the % composition of the following compounds:
    a.    MgCl2            b.    SiO2            c.    (NH4)2S

6.Determine the empirical and molecular formula of the following:
    a.    caffeine, 49.48%C; 5.19%H, 28.85%N and 16.48%O; Molar mass = 194.2.

    b.    octene, 85.7%C and 14.3%H; Molar mass = 112.

   c.    an oxide of phosphorous, 43.7%P and 56.3%O; Molar mass = 284.

7. How many moles of O2 react with or are produced by 6.75 moles of the first reactant shown in each balanced equation?
    a.    2C2H6  +  7O2                4CO2  +  6H2O

   b.    2KClO3                2KCl  +  3O2

    c.    4Fe  +  3O2                2Fe2O3

8.How many grams of the second reactant is needed to react with 20.0 grams of the first reactant in each balanced equation?
    a.    P4  +  6Cl2               4PCl3
    b.    P4O10  +  6H2O                4H3PO4

    c.    Fe2O3  +  3CO                2Fe  +  3CO2

9.Using the three balanced equations below, do 9.a through 9.d for each:
a.   How many grams of the first product can be produced from 20.0 grams of the first reactant and 20.0 grams of the second reactant? 
b.    Which reactant is the limiting reactant?
    c.      How many grams of the excess reactant are reacted?
    d.      How many grams of the excess reactant are left unreacted?

         P4  +  6Cl2 4PCl3                 P4O10  +  6H2O  4H3PO4          Fe2O3  +  3CO 2Fe  +  3CO2

10.A student carried out the reaction shown by reacting 10.0g P4 with excess Cl2 and obtained 35.0g of PCl3.              P4  +  6Cl2              4PCl3
    a.        What is the theoretical yield of PCl3?

    b.        Calculate the % yield of PCl3.