MIDTERM REVIEW UNIT 1: Mass/Measurement Practice Problems 1. Circle the word/phrase that best fits the statement: A. [ PHYSICAL OR CHEMICAL] changes are changes in which the identity of the substance does not change. B. Chemical changes sometimes produce a [ GAS or GEL ] which can be observed by wafting. C. When two clear solutions mix, [NOTHING HAPPENS or A PRECIPITATE] forms producing a cloudy mixture. D. [QUANTITATIVE or QUALITATIVE] properties deal with numbers. E. [PURE SUBSTANCE or MIXTURE] contains only one type of atom or molecule. F. [REACTIVITY, DENSITY, or MELTING] is not a physical property. G. A mixture that is completely uniform in composition is a [HOMOGENEOUS or HETEROGENEOUS] mixture. 2. Indicate whether its a chemical or physical change: A. milk souring D. Chopping wood B. gasoline burning E. Breath fogging a mirror C. Ice melting 3. Indicate whether the material is a COMPOUND, ELEMENT, HOMOGENEOUS MIXTURE, or HETEROGENEOUS MIXTURE. A. hydrogen peroxide D. Sugar B. copper E. stainless steel C. a salad F. Nitrogen Gas G. Ozone 4. Indicate TRUE or FALSE. A. __________________ Elements can be separated easily into simpler substances. B. __________________ Compounds can be separated into simpler substances C. __________________ The properties of compounds are different from those of their components. D. __________________ Allotropes can be described as elements and compounds. E. __________________ Chemical properties are only observed when a substance undergoes a chemical change. 5. Identify the number of sig figs in each measurement: A. 0.370 g B. 70,420 mL C. 5 x 104 m/s D. 0.0039 s E. 7.30 x1014 ms 6. Convert the following: A. 3.5 Liters to Cubic Centimeters D. 0.52 km to m B. 0.75 kg to mg E. 750 microliters to liters C. 4 X 1014 nanoseconds to centiseconds F. 7 Megagrams to milligrams 7 . Perform the following Arithmetic and place the answer in the correct number of sig figs (multiplication/division rules for significant figures trump addition/subtraction rules) A. (21 mL -­‐ 19.0 mL)/4x102 mg B. 734 m X 7.3 x 102m – 3.23x102 m C. (0.0323 kg +0.324 kg) X 8.8x10-­‐1 m2 8. Calculate the number of seconds in the entire month of October. 9. Each chemistry teacher provides 6 test tubes to each lab group. In each class there are 12 lab groups, and the teacher has four classes. There are a total of 5 chemistry teachers. How many test tubes does the chemistry department provide for their students? (Use dimensional analysis) 10. A light year is the distance that light can travel in one year. If the sun is 150,000,000 km away, how many light years is the sun from the earth? Light travels at the speed of 3.0 X108 m/s. Place your answer in scientific notation. 11. What is the cost in dollars for the nails used to build a fence 125 meters long if it requires 30 nails per meter? Assume 40 nails are sold per box at a cost of $3.35 a box. 12. Determine the Volume that a 35.2 grams sample of carbon tetrachloride will occupy if it has density of 1.60 g/mL. 13. The density of ethanol is 0.789 g/mL. What is the mass of a 100 mL sample? UNIT 2: Nomenclature Practice Problems 1) Find the number of protons, neutrons and electrons in the following: Element Protons Neutrons electrons Copper zinc Carbon-­‐12 Carbon-­‐14 Sodium Phosphorus calcium silver tungsten mercury 2) What is average atomic mass of Lithium if 7.42% exists as 6Li (6.015 g/mol) and 92.58% exists as 7Li
(7.016 g/mol)?
3. Neon has two major isotopes, Neon-20 and Neon-22. Out of every 250 neon atoms, 225 will be Neon-20
(19.992 g/mol), and 25 will be Neon-22 (21.991 g/mol). What is the average atomic mass of Neon?
4. What is the atomic mass of Hafnium if out of every 200 atoms, 10 have mass 176.00 g/mol, 38 have
mass 177.00 g/mol, 54 have mass 178.00 g/mol, 28 have mass 179.00 g/mol, and 70 have mass 180.00
g/mol?
5. In a sample of 200 Chlorine atoms, it is found that 151 are 35Cl (34.969 g/mol), and 49 are 37Cl (36.966
g/mol). What is the average atomic mass of Chlorine?
6. Without doing any math, are there more Bromine-79 atoms or more Bromine-80 atoms on earth?
Explain your reasoning.
7. Find the molar mass of the following substances:
Cu2SO4
C20H30O2
HNO3
C5H10O5
HC2H3O2
Na
NaCl
8. Name or write the formula of the following: potassium nitrate _________________ Ammonium phosphate _____________________ sodium phosphate ________________ chromium (IV) chloride ____________________ ammonium phosphide ___________ zinc sulfate ____________________ aluminum oxide __________________ LiClO2 ______________________________ NaMnO4 __________________________ Copper (II) oxide _________________ Fe2O3 ______________________________ 9. How many atoms are in 208 grams of lead? How many atoms are in 12 grams of carbon? How many molecules are in 16 grams of methane (CH4)? Explain the relationship between these numbers. 10. Do the following conversions: a) 36.5 grams of calcium to moles b) 0.598 g of iron to moles c) 1.37 x 103 g of Cu to moles 11. A substance contains 26.57% potassium, 35.36% chromium, and 38.07% oxygen. What is the
empirical and molecular formula if its molar mass is 294.19 g/mol? What is the name of the compound/
12. The compound propylene glycol is used in commercial antifreeze. What is the empirical and molecular
formula if the percent composition is 47.37% carbon, 10.59% hydrogen and 42.04% oxygen and its molar
mass is 76.09 g/mol?
13. An acid is 2.04% hydrogen, 32.65% sulfur, and 65.31% oxygen. Find the empirical and molecular formula and name the acid. The molar mass is 98.08 g/mol. 14. Write the name of the following acids: HF __________________________ H2SO4 __________________________ HCl __________________________ HNO3 __________________________ HC2H3O2 __________________________ HNO2 __________________________ H3PO4 __________________________ HClO4 __________________________ UNIT 3: Chemical Reactions 1) Balance the following reactions:
a)
___ NaNO3 + ___ PbO ! ___ Pb(NO3)2 + ___ Na2O
b) ___ AgI + ___ Fe2(CO3)3 ! ___ FeI3 + ___ Ag2CO3
c)
___ C2H4O2 + ___ O2 ! ___ CO2 + ___ H2O
d) ___ ZnSO4 + ___ Li2CO3 ! ___ ZnCO3 + ___ Li2SO4
e)
___ V2O5 + ___ CaS ! ___ CaO + ___ V2S5
f)
___ Mn(NO2)2 + ___ BeCl2 ! ___ Be(NO2)2 + ___ MnCl2
g) ___ AgBr + ___ GaPO4 ! ___ Ag3PO4 + ___ GaBr3
h) ___ H2SO4 + ___ B(OH)3 ! __ B2(SO4)3 + ___ H2O
i)
___ S8 + ___ O2 ! ___ SO2
j)
___ Fe + ___ AgNO3 ! ___ Fe(NO3)2 + ___ Ag
2) Determine the type of reaction shown and predict the products of each. If the reaction does occur,
balance it. If a reaction will not occur, explain why not:
a)
____ Ag2SO4 + ____ NaNO3 !
b)
____ NaI + ____ CaSO4 !
c)
____ HNO3 + ____ Ca(OH)2 !
d)
____ AlCl3
e)
____ Pb
+ ____ Fe(NO3)3 !
f)
____ Na
+ ____ CaSO4 !
+ ____ (NH4)3PO4 !
3) Double Displacement: Predict the products of the reactions below (names and formulas), balance
the equations, and write the complete ionic and net ionic equations if the reaction occurs. Identify
the spectator ions by circling them in the complete ionic equation.
a)
silver nitrate + potassium phosphate !
b) copper (II) bromide + aluminum chloride !
c)
sodium chromate + copper (II) nitrate !
d) carbonic acid + potassium sulfide !
e)
nitrous acid + barium hydroxide !
4) Balance and determine the products for the following single displacement reactions:
a)
____Al + ____Fe(NO3)2 !
b) ____Na2SO4 + ____ Pb !
c)
____BaCl2 + ____ F2 !
d) ____Fe + ____ HC2H3O2 !
e)
____ Co + ____AuPO4 !
5) Describe the difference between a synthesis and a decomposition reaction.
6) How can you identify a combustion reaction by looking at the reactants and products?
7) Identify the reactions below as single or double displacement, decomposition, synthesis, or combustion:
a)
Mg + HCl → MgCl2 + H2
b)
Na + MgF2 → NaF + Mg
c)
Cl2 + KI → KCl + I2
d)
NaCl → Na + Cl2
e)
Na + O2 → Na2O
f)
Na + HCl → H2 + NaCl
g)
K + Cl2 → KCl
h)
Ca + O2 → CaO
i)
j)
k)
l)
H 2O 2 → 2 H 2O + O 2
N2 + 3H2 → NH3
Cu2O + C → Cu + CO2
CH4 + O2 → CO2 + H2
UNIT 4: Stoichiometry 1.
2.
3.
4.
5.
a.
What is a mole? What is stoichiometry? Why is it important to a chemist? Calculate the mass of one mole of a) water b) acetic acid c) oxygen gas d) zinc phosphate What is Avogadro’s number? How is it related to a mole? Calculate the number of grams in each of the following. 1.5 moles of potassium oxide b.
c.
d.
6.
a.
b.
5.9 moles of sodium 7.24 x 1022 atoms of copper 4.85 x 10-­‐3 moles of silver nitrate Calculate the number of particles (atoms, formula units or molecules) of each of the following: 0.018 mol of Au 3.5 mol of C3H8 c.
d.
150.0 g of sulfur 5.0 g of Na2CO3 7. Complete the questions for the following reaction. Use dimensional analysis. C3H8 + 5O2 3CO2 + 4H2O a. How many moles of oxygen will be needed to react with 0.38 mol of propane, C3H8 ? b. How many moles of water will be produced from the combustion of 50.0 grams of propane? c. How many grams of carbon dioxide is produced from the combustion of 25.5 grams of propane? d. How many molecules of carbon dioxide will be produced from the consumption of 5.6 grams of oxygen? e. How many molecules of propane is burned if 250.0 g of propane is burned? 8. In a reaction of 0.26 mol of NaCl with 0.18 mol of Pb(NO3)2, how many grams of lead(II) chloride will be produced? What is the limiting reagent? 2 NaCl + Pb(NO3)2 PbCl2 + 2 NaNO3 9. Identify the limiting reactant when 0.091 mol of magnesium reacts with 6.4 g of oxygen to produce magnesium oxide. Which is the limiting reagent? 2 Mg + O2 ! 2 MgO 10. If 3.40 g of magnesium oxide is actually produced from the reaction in #9, what is the percent yield? 11. In a reaction between lead (II) nitrate and copper (II) bromide, do the following: a) write the formulas for the reactants and the products and balance the equation b) If 0.67 moles of copper (II) bromide react with 0.52 grams of lead (II) nitrate, how many grams of lead(II) bromide will be produced? c) Which reactant is the limiting reagent? In addition, any of the material from this week will also be on the midterm (calculating molarity, making solutions using molarity, titration and naming molecular compounds) 1. 0.145 g of aluminum metal reacts with 10.0 mL of 1.5 M hydrobromic acid, as shown
below
___ Al
+
___ HBr
→
a. Determine if the reaction happens. If it does, write the formulas and names of the
products and balance the equation.
b. What kind of reaction is this?
c. Using the amounts of aluminum metal and HBr from the equation, determine
which one is the limiting reactant.
2. You are asked to make 200.0 mL of a 0.500 M solution of zinc sulfate. How many
grams of zinc sulfate do you need?
3. You titrated 10.0 mL of HCl with 9.8 mL of 2.0 M NaOH. What is the molarity
of the HCl?
4. Name the following compounds (some are molecular or ionic). Name any acids
using acid naming rules:
a. N2O3
b. CS2
c. P2O5
d. SO2
e. Fe2O3
f. HBr
g. CaCO3