Test VI Study Guide
Mole Conversions
1) 3000 atoms of Mg to grams
1.20x10-19 g Mg
2) 5.0 grams of Na to atoms
1.31x1023 atoms Na
3) 4 moles of H2O to grams
72g H2O
4) 15.0 grams of MgCl2 to molecules
9.6x1022 MgCl2 molecules
5) 20.0 grams of CO2 to moles
0.45 mol CO2
Stoichiometry—Do NOT assume chemical equations are balanced!!!!
1) __2____ H2O
____2____ H2 + _______ O2
If 5.0 grams of O2 gas are produced from this reaction, how many grams of H2O did I
start with?
5.6g H2O
2) __2__ C2H2 + __5___ O2
__4____ CO2 + ___2____ H2O
If I have 14.0 grams of C2H2, how much CO2 gas will I produce from burning?
24.12 L CO2
3) ______ CaCl2 + ______ K2SO4
______ CaSO4 + _____2____ KCl
If 5.0 grams of CaSO4 are produced in this reaction, how many grams of CaCl2 did I have
at the beginning of the reaction?
4.0g CaCl2
Percent Composition
Calculate the percentage for each element.
1) CuBr2 Br: 71.4%
Cu: 29%
2) NaOH Na: 57.5%
O: 40%
3) (NH4)2S N: 41.2%
H: 2.5%
H: 11.8%
S: 47%
4) N2S2 N: 30.4% S: 69.6%
Empirical vs. Molecular Formula
1) If an empirical formula for a chemical compound is P2O5 and the compound has a
molar mass of 283.89g, what is the molecular formula? P4H10
2) What is the molecular formula of a compound having an empirical formula of CH
and a formula mass of 78.110 g? C6H6
3) An unknown compound was found to have a percent composition as follows:
47.0% K, 14.5% C, and 38.5% O. What is its empirical formula? If the true molar
mass of the compound is 166.22 g/mol, what is its molecular formula?
Empirical: KCO2
Molecular: K2C2O4
4) What is the empirical formula of a compound with 40% C, 6.72% H, and 53.9%
O? CH2O
Hydrates
Write either the chemical name or formula for the following—
1) copper (II) sulfate pentahydrate
CuSO45H2O
2) Na2CO310H2O sodium carbonate decahydrate
3) Zinc sulfate heptahydrate
ZnSO47H2O
Glassware Questions
These are examples of the types of questions to expect on glassware and lab equipment.
1) To light a Bunsen burner, what is the proper order of steps?
a) Close burner slits, turn the burner valve 2 turns to the left, turn gas on
b) ensure burner is stable, close burner slits, turn gas on, turn the burner valve 2
turns to the left
c) ensure burner is stable, turn the burner valve 2 turns to the left, turn gas on,
close burner slits
d) turn gas on, close burner slits, turn the burner valve 2 turns to the left, ensure
burner is stable
e) None of the above
2) What type of glassware is used to accurately measure liquids?
a) beaker
b) graduated cylinder
c) Erlenmeyer flask
d) medicine dropper
3) You need to set a chemical compound out to dry overnight. What type of
equipment/glassware are you likely to use to hold the compound?
a) weigh boat
b) Klim wipe
c) wire gauze
d) watch glass
4) Name the 2 functions of a fire blanket.
Privacy shield for safety shower
Stop fire
5) What type of lab equipment is used to handle hot glassware or ceramic contains?
a) wire gauze
b) crucible tongs
c) test tube holder
d) crucible