Ch. 5, 6, & 11  conversion factors, moles, & light  test                      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.  [45 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.  The density of an object is  5.0 g / mL.  [10 points]

a.  if the mass = 42 g, then its volume is __.

b.  if the volume is 7.25 mL, then its mass 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.   Q3b problem

 

4.  determine: __.  [15 points]

a.  725 milligrams of H2 O =  __ moles of H2 O ?

b.  7.25 billion CO2 molecules =  ___ grams of CO2 ?

c.  888 micromoles of MgCl2 =  __  grams of MgCl2 ?