Ch. 5, 6, & 11  conversion factors, moles, & light  test                      Honors  Chem

For problems involving calculations, show the relevant equation (or formula and conversion factor(s)), show your work in an organized manner, put the proper units in your calculations / answer, and have the proper number of significant figures in your answer.  [55 points]

1.  A photon of light has a wavelength of 275 nm.  [10 points]

a.   what is its frequency ?

b.  what is its energy ?

2.  A 15.0 g sphere has a density of 5.0 g / mL.  [10 points]

a.  what is its volume ?

b. what is its radius, in mm ?  [hint:  the volume of a sphere is .

3.   fill-in the blank.  [10 points]

a.  5.36  +  12.218  =  ______  [need not show your work]

b.  5.00 ÷ 9.0  =  _______  [need not show your work]

c.  Using scientific notation, 0.002360 =   ______________________.  [need not show your work]

d. 4.  determine: __.  [15 points]

a.  725 milligrams of water =  __ moles of water ?

b.  7.25 billion carbon dioxide molecules =  ___ grams of carbon dioxide ?

c.  888 micromoles of magnesium chloride =  __  grams of magnesium chloride ?

5.  A compound contains

48.65 % carbon
8.11 % hydrogen
43.24 % oxygen

what is the compound’s empirical formula ?   [10 points]