Download Review of Moles and Stoichiometry

Review of Moles and Stoichiometry
Chemistry
1.) What is 1 mole?
2.) A mole was originally define with respect to one particular isotope. What
isotope is this, and how is 1 mole defined with respect to it?
3.) What is Avogadro’s Number?
4.) a.) How many grapes are there in 1 mole of grapes?
b.) How many grapes are there in 0.5 moles of grapes?
5.) What is the molar mass for the following compounds:
a.) CaCl2
b.) Ca(NO3)2
6.) Consider 7.5 grams of water.
a.) How many moles of water molecules does this sample represent?
b.) How many water molecules does this sample represent?
c.) How many hydrogen atoms does this sample represent?
7.) Find the mass of 1.25 moles of H2SO4.
8.) How many moles of sodium hydroxide are there in 1.505 x 1024 units of
NaOH?
9.) How many molecules of CO2 are there in 110 grams of CO2?
10.) If you burned 4.0 x 1024 molecules of natural gas (methane, CH4), during a
laboratory experiment, what mass of methane did you burn?
11.) A room has length, width, and height dimensions of 5m x 6m x 4m. One
liter has a dimension of 0.1 m x 0.1m x 0.1m. Assuming the room is at
STP, how many moles of gas are there in the room?
12.) A chemical reaction produces 1.52 moles of H2. What volume does this
H2 gas occupy?
13.) A sample of urea contains 1.121 g N, 0.161 g H, 0.480 g C, and 0.640 g O.
a.) By mass, what percent of urea is C and what percent is O?
b.) What is the empirical formula of urea?
14.) A sample of a compound with a mass of 0.453 grams has the following
composition: 36% calcium and 64% chlorine. When this compound is
decomposed into its elements, what mass of each element will be
recovered?
15.) A compound was analyzed in a lab to determine its empirical formula.
Decomposition of the compound at standard temperature and pressure
produced 9.00 g carbon, 16.8 L hydrogen, and 2.80 L oxygen.
a.) What is the empirical formula for this compound?
b.) The molar mass of the compound is 116 g/mol. What is its molecular
formula?
16.) Phenylalanine is an essential amino acid whose chemical composition is
65.5% carbon, 6.67% hydrogen, 8.48% nitrogen, and 19.4% oxygen.
What is the empirical formula for phenylalanine?
17.) Ammonium nitrate decomposes to dinitrogen oxide and water by the
reaction:
 N2O + 2 H2O
NH4NO3 
If 3.2 moles of ammonium nitrate are decomposed, how many moles of
water will form?
18.) Consider the reaction between iron and oxygen to form iron oxide:
 2 Fe2O3 (s)
4 Fe(s) + 3O2 (g) 
a.) If 25 g of oxygen react with more than enough iron, how many grams
of Fe2O3 will form?
b.) 23.5 grams of iron will react with exactly how many liters of O2 gas at
STP?
19.) How many milliliters of oxygen gas at STP are released from the
decomposition of 3.2 grams of calcium chlorate as described by the
equation:
 CaCl2 + 3O2
Ca(ClO3)2 
20.) The reaction between nitrogen and hydrogen to produce ammonia, NH3, is
given by:
 2NH3 (g)
N2 (g) + 3 H2 (g) 
If 3 moles of N2 react with 8 moles of H2, which gas is the limiting
reactant?
21.) Methanol (CH3OH), also called methyl alcohol, is the simplest alcohol. It
is used a as fuel in race cars and is a potential replacement for gasoline.
Suppose 68.5 kg CO (g) is reacted with 8.60 kg H2 (g). This reaction is:
 CH3OH (l)
2 H2 (g) + CO (g) 
a.) What is the limiting reactant?
b.) How many grams of CH3OH would be predicted to form (this is called
the theoretical yield)?
c.) If 3.57 x 104 g actually was produced, what is the percent yield of
methanol?