Test Review
Name:_____________________________
AP chemistry Chapter 3
Let’s see about reviewing the concepts we’ve learned in this unit!
1. Consider this mass spectrum for the element boron to the
right.
a. How many naturally occurring isotopes does boron
have?
b. Calculate the atomic mass of boron-­­ check your
answer with the atomic mass on the periodic table.
Show Your work!
c. How does boron’s atomic mass compare with the mass numbers of its isotopes?
2.) A nitrate of lead is found to contain 45.52% lead. What is the formula for this salt?
3.) A hydrocarbon with a molar mass of approximately 85, is found to contain 85.7% carbon by mass.
a.) calculate its empirical formula:
b.) Determine its molecular formula:
4) Calculate number of oxygen atoms in 20.00g of zinc phosphate.
5). Vanillin, a flavoring agent, is made up of carbon, hydrogen and oxygen atoms. When a sample
of vanillin weighing 2.500 grams is burned in oxygen, 5.79 grams of carbon dioxide as well as
1.18 grams of water are obtained.
a.) Use the mass of carbon dioxide produced in combustion to calculate the mass of carbon in
the original sample vanillin:
b.) What mass of hydrogen is found in this sample of vanillin?
c.) How much oxygen is in the original 2.500-gram sample of the vanillin?
d.) Use the information from above to calculate the empirical formula for vanillin:
6). Aspirin (C9H8O4) is synthesized by reacting salicylic acid (C7H6O3) with acetic anhydride (C4H6O3).
The balanced equation is written below:
C7H6O3
+
C4H6O3  C9H8O4 +
HC2H3O2
a) What mass of acetic anhydride is needed to completely consume 1.00 x 10 2 g salicylic acid?
b) What is the maximum mass of aspirin that could be generated from this reaction?
c) If 34.6 g of acetylsalicylic acid (Aspirin) are generated in the lab you do, what is the percent yield?
7). Given the following information and reaction: If you start with 14.8 g of C3H8 and 3.44 g of O2,
____C3H8 + ____ O2 -->
___CO2
+ ____ H2O
I
______
______
_______
_______
C
______
______
_______
_______
E
______
______
_______
_______
a) determine the limiting reagent;
b) determine the number of moles of carbon dioxide produced;
c) determine the number of grams of H2O produced;
d) determine the number of grams of excess reagent left.
8). You have 32.2 g of BaCl2 and 17.8 g Na2SO4. They react and produce barium sulfate and sodium chloride.
a) Write the reaction equation
b) determine the limiting reagent;
c) determine the number of grams of BaSO4 produced;
d) which substance is in excess, calculate the amount in excess.
9). How many Cl-1 ion in 1 mole of aluminum chloride compound?
10). Calculate the sodium ion in 2.00 g of sodium phosphate.