CHEMISTRY WKST
CH. 6 REVIEW
NAME: _______________________________________
BE SURE ALL CALCULATIONS’ ANSWERS ARE IN THE CORRECT NUMBER OF SIGNIFICANT DIGITS.
1) What is Avogadro’s Number? ________________________
2) Given 1 mol of Mg atoms, what two quantities are equivalent to this? (mass, and number of atoms)
a)
b)
3) What two ratios do the subscripts of a formula give?
a)
b)
4) Determine the molar mass of the following.
a) BaCl2
b) P4O10
c) Pb(C2H3O2)4
d) Ba(OH)2•8H2O (this is called a “hydrate”; you find the molar mass of Ba(OH)2 and then add the mass of 8 H2O to
it)
5) Determine the moles of the following.
a) 125 g CO2
23
b) 3.221 x 10 NH3 molecules
23
c) 2.0 x 10 oxygen atoms—find moles of C6H12O6
6) Determine the mass of the following.
a) 0.13 mol NaCl
23
b) 2.89 x 10 N2O5 molecules
22
c) 1.000 x 10 Ag atoms
7) How many oxygen atoms are in 75 g of Fe2O3?
8) In a NaCl(aq) solution, what is the:
a) solute?
b) solvent?
9) What is the molarity of a solution having 12 g Pb(NO3)2 dissolved in 825.0 mL of solution?
10) What mass of NaOH is needed to make 1.750 liters of a 2.25 M NaOH solution?
11) What volume must a solution be, if there is 205 g of NH4Cl, in order to have a 0.8 M NH4Cl solution?
12) Determine the percent by mass of oxygen in the following compounds.
a) CuSO4
b) Ba(NO3)2
13) A solution is made up of 60.0 g NaCl and 500.0 g water. What is the percent of NaCl in the solution?
14) Determine the mass of Mg(NO3)2 needed to make a 22.25% Mg(NO3)2 solution with 500.0 g H2O.
15) Determine the mass of Zn in 50.00 g ZnSO4.
16) Hemoglobin is the protein that transports oxygen in mammals. Hemoglobin is 0.342% Fe by mass, and each
hemoglobin molecule contains 4 iron atoms. Calculate the molar mass of hemoglobin.
17) Write the empirical formula for the following compounds.
a) Vitamin C, C6H8O6
b) Benzene, C6H6
c) Nutra-Sweet, C14H18N2O5
-2-
18) A 2.62 g sample of S was allowed to react with an excess of Cl to produce 8.44 g of a product that contains only sulfur
and chlorine. What is the empirical formula of this compound?
19) A substance was found to be made up of 60.8% Na, 28.5% B, and 10.5% H. What is the empirical formula of this
compound?
20) If the empirical formula of a compound is C2HCl and its molar mass is 181.4 g/mol, what is its molecular formula?
21) A compound having an approximate molar mass of 165-170 g has the following percentage composition by mass:
42.87% carbon, 3.598% hydrogen, 28.55% oxygen, and 25.00% nitrogen. Determine the empirical and molecular
formula of this compound.
22) Using the conversion table given to you, perform the following conversions using the dimensional analysis method.
a) 100.0 yd → m
b) 2.00
→
−4
c) 6.942 x 10
→
d) 55.2°F → K
e) −44°C → °F
23) How does a Kelvin degree compare to a Celsius degree?
24) Hydrogen has three different isotopes—hydrogen-1, hydrogen-2, and hydrogen-3—and they all have different
masses. Yet, the periodic table only gives one atomic mass. Why?
25) What is the purpose of distilling a solution?
26) In the lab you did, the solution that was distilled was colored yet the distillate was clear. Is this an example of a
chemical or a physical change? Why?
27) When the steam is converted back into liquid water, does the water lose energy or take on energy? Would this be
endothermic or exothermic?
28) We have done labs where we have filtered and distilled a mixture. Why is it that when the original mixture was
colored, distilling gave us a clear liquid at the end but the filtrate when filtering was still colored?
29) Given two solids placed into water, what property of the solids would allow us to separate the two solids from each
other by filtering?
30) In the molar ratio lab, the chemical equation for the reaction was: Fe(s) + CuSO 4(aq) → FeSO4(aq) + Cu(s)
a) What was the mole ratio between Fe(s) and Cu(s)?
b) If 0.75 mol Fe reacted, how many moles of FeSO4 was produced?
c) The CuSO4 solution was supposed to be in excess to make sure all the iron reacted. How do we know this took
place?
31) Explain how you would find the density of some odd shaped object.
32) What is the density of water?
33) What is the equation for density?
VOCAB TO KNOW:
amu
average atomic mass
concentration
density
distillation
empirical formula
filtrate
molar mass
molarity
mole
molecular formula
solute
solvent