Introduction to Chemistry - Matter and Energy



Honors Chemistry - Final Exam Study Guide 2015

Measurements and Calculations (Math)

➢ Scientific Notation

➢ Metric System and SI Units

➢ Review of Measurements/Uncertainty

➢ Significant Figures

➢ Dimensional Analysis

Chemical Composition

➢ Average Mass, Atomic Mass

➢ The Mole, Molar Mass

➢ Percent Composition

➢ Formulas of Compounds

• Empirical Formulas

• Molecular Formulas

Chemical Quantities – Ch 11

➢ Mole-Mole Relationships

➢ Mass Calculations

➢ Stoichiometry

• Mass-Mass

• Limiting Reactants

• Percent Yield

Modern Atomic Theory

➢ Electromagnetic Radiation Ch 5

• wavelength

• frequency

• photons

• Energy Emission

➢ Bohr Model Ch 5

➢ Wave Mechanical Model Ch 5

• Orbitals

• Energy Level diagrams

• Electron Configuration and relationship with the PT

➢ Atomic Properties and Trends on PT Ch 6

• State of Matter

• Ionization Energy

• Atomic Size

• Electronegativity

Bonding

➢ Ionic and Covalent bonds- how formed (review electronegativity) Ch 7 and Ch 8

➢ Polarity and Dipoles Ch 8

➢ Forming Ionic Bonds/predicting formulas Ch 7

➢ Lewis Structures Ch 8

• Single bonds

• Multiple Bonds

➢ Molecular Structures – VSEPR Ch 8

• Single bonds

• Multiple Bonds

Useful Information:

K = *C + 273

Density = mass/volume

1Kcal = 1Cal = 1000 cal

22.4 L = 1 mol of gas (at STP)

Avogrado’s number (6.022 x 1023)

Percent Yield = actual yield/theoretical yield x 100

c = λ· υ

Ephoton = h · υ

Planck’s constant (h) = 6.626 x 10-34 J·s

Speed of Light (c) = 3.00 x 108 m/s

Quantum Numbers:

n: principal energy level (values 1 – 7)

l: sublevel number (range from 0 to n-1)

ml: orbital values (range is –l to +l; includes zero)

ms: spin value + ½ and – ½

Practice Problems

Measurements and Calculations (Math)

1. How many significant figures are in each of the following?

100

1180.3

0.00198

1.001

67.342

0.0103

4.10 x 104

2. Express the results of each calculation to the correct number of significant figures.

1.8 x 2.93

0.002/0.041

0.00031 x 4.030

495.0/390

5024 x 19.2

91.3 x 2.10 x 7.7

8.003 x 4.93/61.05

3. A family consumes 2.5 gallons of milk per week. How many liters of milk do they need to buy for one week? (1 L = 0.908 quart; 1 gallon = 4 quarts)

4. Determine the number of significant figures in each measurement.

0.000010 L

907.0 km

2.4050 x 10-4 kg

300,100,000 g

5. Round each number to five significant figures. Write your answers in scientific notation.

0.000249950

907.0759

24,501,759

300,100,500

6. Complete the following calculations. Round off your answers as needed.

52.5 g + 309.1 g + 77.214 g

927.37 mL – 231.458 mL

245.01 km x 2.1 km

529.31 m / 0.9000 s

Chemical Composition

1. A sample with a mass of 4.100 x 105 amu is 25.00% carbon, and 75.00% hydrogen by mass. How many atoms of carbon and hydrogen are in the sample?

2. Calculate the molar mass of the following substances:

Fe2O3

NH3

C2H5OH

Pb(OH)2

Cu(NO3)2

Na2SO4

3. How many grams of potassium sulfate are in 0.623 mol potassium sulfate?

4. Calculate the mass percent of each element in the following substances:

CH3NH2

H2SO4

5. The molecular formula of the gas acetylene is C2H2. What is the empirical formula?

6. The compound benzamide has the following percent composition.

C = 69.40% H = 5.825% N = 11.5% O = 13.21%

What is the empirical formula?

7. The empirical formula for a compound used in the past as a green paint pigment s C2H3As3Cu2O8. The molar mass is 1013.71 g. What is the molecular formula?

Chemical Quantities

1. Determine all the mole ratios for the following balanced chemical equations.

a. N2 + O2 ( 2NO

b. 4NH3 + 5O2 ( 4NO + 6H2O

c. 4HCl + O2 ( 2H2O + 2Cl2

2. The carbon dioxide exhaled by astronauts can be removed from a spacecraft by reacting it with lithium hydroxide (LiOH). The reaction is as follows: CO2 + 2LiOH ( Li2CO3 + H2O. An average person exhales about 20 moles of CO2 per day. How many moles of LiOH would be required to maintain two astronauts in a spacecraft for three days?

3. Balance the following equation and answer the questions below.

KClO3 ( KCl + O2

a. How many moles of O2 are produced from 10 moles of KClO3?

b. How many moles of KCl are produced using 3 moles of KClO3?

c. How many moles of KClO3 are needed to produce 50 moles of O2?

4. Calculate the mass of sodium chloride (NaCl) produced when 5.50 moles of sodium reacts in excess chlorine gas.

5. How many grams of chlorine gas must be reacted with excess sodium iodide (NaI) to produce 6.00 moles of sodium chloride?

a. balance the equation: NaI + Cl2 ( NaCl + I2

b. Perform the calculation

7. Balance each equation and solve the problem.

a. If 40.0 g of magnesium reacts with excess hydrochloric acid, how many grams of magnesium chloride are produced? Mg + HCl ( MgCl2 + H2

b. Determine the mass of copper needed to react completely with a solution containing 12.0g of silver nitrate. Cu + AgNO3 ( Cu(NO3)2 + Ag

c. How many grams of hydrogen chloride are produced when 15.0 g of sodium chloride reacts with excess sulfuric acid? NaCl + H2SO4 ( Na2SO4 + HCl

8. Ammonia is one of the most common chemicals produced in the United States. It is used to make fertilizer and other products. Ammonia is produced by the following chemical reaction.

N2 + 3H2 ( 2NH3

a. If you have 1.00 x 103 g of nitrogen and 2.50 x 103 g of hydrogen, which is the limiting reactant in the reaction?

b. How many grams of ammonia can be produced from the amount of limiting reactant available?

c. Calculate the mass of excess reactant that remains after the reaction is complete.

9. Calculate the percent yield for each chemical reaction based on the data provided.

a. theoretical yield: 25g actual yield: 20g

b. theoretical yield: 55g actual yield: 42g

c. theoretical yield: 5.2g actual yield: 4.9g

10. In an experiment, 10.0 g of magnesium reacted with excess hydrochloric acid forming magnesium chloride. Mg + 2HCl ( MgCl2 + H2 At the completion of the reaction, 29.5 g of magnesium chloride was produced. Calculate the theoretical yield and the percent yield.

Modern Atomic Theory

1. A helium-neon laser emits light with a wavelength of 633nm. What is the frequency of this light?

2. What is the wavelength of X-rays having a frequency of 4.80 x 1017 Hz?

3. An FM radio station broadcasts at a frequency of 98.5 MHz. What is the wavelength of the station’s broadcast signal?

4. Calculate the energy of a gamma ray photon whose frequency is 5.02 x 1020 Hz.

5. What is the difference in energy between a photon of violet light with a frequency of 6.8 x 1014Hz and a photon of red light with a frequency of 4.3 x 1014 Hz?

6. Calculate the energy of a photon of ultraviolet light that has a wavelength of 49.0 nm.

7. How many electrons an the second principal energy level hold? How many electrons can the third principal energy level hold? Explain the difference in these numbers of electrons.

8. When writing the electron configuration of an atom, in what general order are the sublevels written?

9. Write the electron configurations of the following elements:

a. sulfur

b. calcium

c. bromine

d. magnesium

10. Write electron-dot structures for the following elements:

a. Nitrogen

b. Aluminum

c. Neon

d. Strontium

e. Antimony

11. Rank the following elements by increasing atomic radius: carbon, aluminum, oxygen, potassium.

12. Rank the following elements by increasing electronegativity: sulfur, oxygen, neon, aluminum.

13. What is the difference between electron affinity and ionization energy?

14. Why does fluorine have a higher ionization energy than iodine?

15. Why do elements in the same family generally have similar properties?

Bonding

For each of the following molecules, draw the Lewis structure (with any resonance structures, if applicable), indicate the molecular shapes and bond angles, indicate the molecular polarity (if any), and identify the sigma and pi bonds in each compound.

1. carbon tetrafluoride

2. BF3

3. NF3

4. H2CS

5. carbonate ion

6. CH2F2

7. nitrate ion

8. O2

9. PF3

10. H2S

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