Chemistry Goal 2 Study Guide Answers

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Chemistry Goal 2 Study Guide
1. Collision Theory- molecules must collide in order to react, and they must collide in the correct or
appropriate orientation and with sufficient energy to equal or exceed the activation energy.
2. Draw a potential energy diagram for an exothermic and endothermic reaction. Label the energy of
the reactants, products, activation energy, and the heat of reaction.
3. Determine if a chemical reaction has occurred based on the following criteria:
a. precipitate formation
b. color change
c. temperature change
d. Production of a gas
4. Write and balance chemical equations predicting products in a reaction. Classify each type of
reaction.
a. 2 N2 + 3 H2  2 NH3
synthesis
b. 2 NaCl + 1 F2  2 NaF + 1 Cl2
single replacement
c. 1 Ag2SO4 + 2 NaNO3  1 Na2SO4 + 2 AgNO3
double replacement
d. 2 C3H6 + 9 O2  6 CO2 + 6 H2O
combustion
e. 2 Na + 1 CaSO4  1 Na2SO4 + 1 Ca
single replacement
5. Write a balanced net ionic equation for the reaction that occurs in each of the following cases.
Assume that all soluble reactants are added in the form of aqueous solutions. Indicate precipitates
that are formed. If no reaction occurs, then write "NO RXN" and do not write a balanced equation,
a. potassium phosphate + magnesium nitrate → magnesium phosphate + potassium nitrate
i. 2 K3PO4 + 3 Mg(NO3)2  Mg3(PO4)2(s) + 6 KNO3
ii. 6 K+1 + 2 PO4-3 + 3 Mg+2 + 6 NO3-1  Mg3(PO4)2(s) + 6 K+1 + 6 NO3-1
iii. 2 PO4-3 + 3 Mg+2  Mg3(PO4)2(s)
b. calcium chloride + aluminum nitrate → NO RXN
c. calcium hydroxide + ammonium chloride → NO RXN
6. Use activity series to predict whether a single replacement reaction will take place.
a. ___I2(g) +___NaBr(s)NO RXN
b. ___Pb(s) +___H2O(s) NO RXN
c. 1 Sr(s) + 2 H2O(l) Sr(OH)2 + H2
d. 1 Mg(s) +1 Co(NO3)2(g) Mg(NO3)2 + Co
7. Use the solubility rules to determine the precipitate in a double replacement reaction if a reaction
occurs.
a. CaCl2(aq) + Na3PO4(aq) → Ca3(PO4)2(s) + NaCl
b. KNO3(aq) + MgI2(aq) → NO RXN
8. Mole Conversions
a. How many moles of magnesium is 3.01 x 1022 atoms of magnesium? 0.05 moles
b. How many molecules are there in 4.00 moles of glucose, C6H12O6? 2.408x1024 molecules
c. How many moles in 28 grams of CO2 ? 0.636 mol
d. What is the mass of 5 moles of Fe2O3 ? 798.5 g
e. Determine the volume, in liters, occupied by 0.030 moles of a gas at STP. 0.672 L
f. How many moles of argon atoms are present in 11.2 L of argon gas at STP? 0.5 mol
g. Find the mass in grams of 2.00 x 1023 molecules of F2. 12.624 g
h. Determine the volume in liters occupied by 14 g of nitrogen gas at STP. 11.2 L
9. Stoichiometry Problems
a. 6 NaOH + 2 Al  2 Na3AlO3 + 3 H2
i. How many grams of aluminum are required to produce 913g of hydrogen? 8217 g Al
ii. How many grams of Na3AlO3 can be formed from 8167 g of NaOH? 9800 g
b. Given the reaction S + O2  SO2
i. How many moles of sulfur must be burned to give 0.567 moles of SO2? 0.567 mol
ii. How many moles of SO2 can be produced from 67.1 moles of O2? 67.1 mol
c. Balance the chemical equation and use it to solve for the following problems:
i. Al(s) + H2SO4(aq) →AlSO4 + H2
1. If 45.60 L of Hydrogen gas forms at STP, what volume of Hydrogen sulfate
was used? 45.60 L
2. What volume of hydrogen gas will be produced @ STP from the complete
rxn of 36.1g of Aluminum? 29.9 L
10. What’s the empirical formula of a molecule containing 18.7% lithium, 16.3% carbon, and 65.0%
oxygen? If the molar mass of the compound is 73.8 grams/mole, what’s the molecular formula?
Li2CO3
11. Calculate the mass percent of carbon, nitrogen and oxygen in acetamide, C2H5NO.
12.
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40.7 % C
23.7% N
27.1% O
A chemist heats a sample of hydrated lithium nitrate which weighs 170 grams and finds, after
heating that it weighs 95.3 grams. Find the correct formula of the hydrate and name it.
LiNO3*3H2O
lithium nitrate trihydrate
Define: specific heat capacity, heat of fusion, and heat of vaporization.
a. Specific heat capacity- the amount of heat energy required to raise the temperature of 1 g
of a substance by 1 degree Celsius.
b. Heat of fusion- the amount of heat energy required to melt a substance at its melting point.
c. Heat of vaporization- the amount of heat energy required to vaporize a substance at its
boiling point.
Draw a heating curve for water. Label solid, liquid, gas, freezing, melting, condensation,
vaporization, heat of vaporization, heat of fusion, boiling point, and melting point. (in class)
Complete calculations of: q = m*Cp*∆T, q = m*∆Hf, q = m*∆Hv, and qlost = (-qgain)
a. A 15.75-g piece of iron absorbs 1086.75 joules of heat energy, and its temperature changes
from 25°C to 175°C. Calculate the specific heat capacity of iron. 0.46 J/g*C
b. How much energy is required to melt 850. grams of ice? 283,900 J
c. How much energy is required or released to change 100.0 g of ice at -10.0°C to steam at
118°C? 306,896 J
Ideal Gas Equation
a. If I have 4 moles of a gas at a pressure of 5.6 atm and a volume of 12 liters, what is the
temperature? 204.6 K
b. If I have an unknown quantity of gas at a pressure of 1.2 atm, a volume of 31 liters, and a
temperature of 87 0C, how many moles of gas do I have? 1.26 mol
Combined Gas Laws
a. If I initially have 4.0 L of a gas at a pressure of 1.1 atm, what will the volume be if I increase
the pressure to 3.4 atm? 1.29 L
b. A toy balloon has an internal pressure of 1.05 atm and a volume of 5.0 L. If the temperature
where the balloon is released is 200 C, what will happen to the volume when the balloon
rises to an altitude where the pressure is 0.65 atm and the temperature is –150 C? 7.1 L
18. Dalton’s Law
a. A metal tank contains three gases: oxygen, helium, and nitrogen. If the partial pressures of
the three gases in the tank are 35 atm of O2, 5 atm of N2, and 25 atm of He, what is the total
pressure inside of the tank? 65 atm
b. Blast furnaces give off many unpleasant and unhealthy gases. If the total air pressure is 0.99
atm, the partial pressure of carbon dioxide is 0.05 atm, and the partial pressure of hydrogen
sulfide is 0.02 atm, what is the partial pressure of the remaining air? 0.92 atm
Extra Practice Problems:
1 Pb(OH)2 + 2 HCl  2 H2O + 1 PbCl2
1 C3H8 + 5 O2  3 CO2 + 4 H2O
1 FeCl3 + 3 NaOH  1 Fe(OH)3 + 3 NaCl
2 HNO3 + 1 Ca(OH)2  1 Ca(NO3)2 + 2 H2O
1 CaCO3  1 CaO + 1 CO2
AlCl3 + (NH4)3PO4  3 NH4Cl + AlPO4
1 Pb + 1 Fe(NO3)3  1 Pb(NO3)3 + 1 Fe
Use activity series to predict whether a single replacement reaction will take place.
a. 1Ca(s) +2H2O(l)1 Ca(OH)2 + 1 H2
b. 1Mg (s) +2H2O(g) 1 Mg(OH)2 + 1 H2
c. ___Br2(l) +___NaCl(s)no reaction
d. 4Sb(s) +3O2(g)2 Sb2O3
27. Use the solubility rules to determine the precipitate in a double replacement reaction if a reaction
occurs.
a. 3 KOH(aq) + 1 Fe(NO3)3(aq) → Fe(OH)3(s) + 3 KNO3
b. NaC2H3O2(aq) + CaS(aq) → NO RXN
c. 1 K2SO4(aq) + 1 Pb(NO3)2(aq) → 1 PbSO4(s) + 2 KNO3
28. How many moles are 1.20 x 1025 atoms of phosphorous? 19.9 mol
29. How many atoms are in 0.750 moles of zinc? 4.52x1023 atoms of zinc
30. How many molecules are in 0.400 moles of N2O5? 2.408x1023 molecules
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26.
31. Find the number of moles of argon in 452 g of argon. 11.3 moles
32. Find the grams in 1.26 x 10-4 mol of HC2H3O2. 7.56x10-3 grams
33. Find the mass in 2.6 mol of lithium bromide. 225.7 grams
34. What is the volume of 0.05 mol of neon gas at STP? 1.12 L
35. What is the volume of 1.2 moles of water vapor at STP? 26.88 L
36. How many oxygen molecules are in 3.36 L of oxygen gas at STP? 9.03x1022 molecules
37. Find the mass, in grams, of 1.00 x 1023 molecules of N2. 4.65 grams
38. How many particles are there in 1.43 g of a molecular compound with a molar mass of 233 g/mol?
3.69x1021 particles
39. Calculate empirical formula from mass or percent using experimental data. Calculate molecular
formula from empirical formula using molecular weight.
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a. What’s the empirical formula of a molecule containing 65.5% carbon, 5.5% hydrogen, and
29.0% oxygen? If the molar mass of the compound is 110 grams/mole, what’s the molecular
formula? C3H3O
Calculate the COMPLETE percentage composition (by mass) of the following.
a. iron (III) oxide 69.9% Fe; 30.1% O
b. barium phosphate 68.4% Ba; 10.3% P; 21.3% O
What is the percentage of sodium (by mass) in sodium phosphate? 42.1% Na
For the hydrate sodium sulfate decahydrate, calculate the following:
a. the percent of sodium (by mass) in the hydrate 14.2% Na
b. Percent of TOTAL oxygen (by mass) in the hydrated compound. 78.3% O
c. Percent of water (by mass) in the hydrate 55.9% H2O
How many joules of heat are needed to raise the temperature of 10.0 g of aluminum from 22°C to
55°C, if the specific heat of aluminum is 0.90 J/g°C? 297 J
To what temperature will a 50.0 g piece of glass raise if it absorbs 5275 joules of heat and its specific
heat capacity is 0.50 J/g°C? The initial temperature of the glass is 20.0°C. 231O C
Calculate the heat capacity of a piece of wood if 1500.0 g of the wood absorbs 6.75×104 joules of
heat, and its temperature changes from 32°C to 57°C. 1.8 J/goC
How much energy is required vaporize 75. grams of water? 169,500 J
How much energy is required or released to …
a. Melt 15 g of ice at 0°C and heat the water to 22°C? 6389.4 J
b. Condense 15 g of steam at 100°C and cool the water to 22°C? 38,790.6 J
If I contain 3 moles of gas in a container with a volume of 60 liters and at a temperature of 400 K,
what is the pressure inside the container? 166.2 kPa
If I have 7.7 moles of gas at a pressure of 0.09 atm and at a temperature of 56 0C, what is the volume
of the container that the gas is in? 2311 L
If I have 17 moles of gas at a temperature of 67 0C, and a volume of 88.89 liters, what is the pressure
of the gas? 540.4 kPa
A small research submarine with a volume of 1.2 x 105 L has an internal pressure of 1.0 atm and an
internal temperature of 150 C. If the submarine descends to a depth where the pressure is 150 atm
and the temperature is 30 C, what will the volume of the gas inside be if the hull of the submarine
breaks? 767 L
People who are angry sometimes say that they feel as if they’ll explode. If a calm person with a lung
capacity of 3.5 liters and a body temperature of 360 C gets angry, what will the volume of the
person’s lungs be if their temperature rises to 390 C. Based on this, do you think it’s likely they will
explode? 3.53 L
790 torr of gas is collected over water at 25 degrees Celsius. (Vapor pressure of water is 23.12 torr
at 25 degrees Celsius). What is the partial pressure of the gas collected? 766.88 torr
A 250. mL sample of O2 is collected over H2O at 25oC and 760.0 mm Hg pressure. What is the
pressure of the dry gas alone? (Vapor pressure of water at 25oC = 23.8 mm Hg) 736.2 mm Hg
150 mL of oxygen is collected over water at 19.0oC and 750 torr. If the dry volume becomes 100 mL
and the pressure becomes 1.00 atm, what will be the new temperature? 201.7 K
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