Download Conversion Factors

CHEMISTRY SEMESTER 1 REVIEW
Conversion Factors
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Calculate the number of milliseconds in 1.75 years.
Calculate the height of a rocket 0.25 miles high in centimeters. (2.54 cm = 1.0 inch) (1 mile = 5,280 feet)
A chemistry student needed to convert 2.5 mg to kg.
Density = mass/volume
4. A piece of metal has the dimensions of 2 cm long, 5 cm wide, and 7 cm thick. If the metal has a mass of 85
grams, what is the density?
5. Find the density of a chunk of mineral with a mass of 225 grams and a volume of 15 cm3.
Chemical and Physical Properties and Changes
Label each of the following as PC (physical change), CC (chemical change), PP (physical property), or CP
(chemical property)
6. _____ melting a penny
9. _____ dew forms on the windshield
7. _____ lunch digesting in your stomach
10. _____ water is converted to hydrogen and oxygen
8. _____ the density is 6 g/ml
11. _____ carbon conducts electricity
State which of the following are HE (heterogeneous) and which are HO (homogeneous) mixtures.
12.______ sand in water
14. _____ sand and sugar stirred together
13.______dust in the air
15. _____ tomato sauce with meat balls
Name each element. How many protons, neutrons, electrons do the atoms of the following elements have?
16. [Ne]
17. [Xe]
18. [Ar]
19. [Kr]
20. [Ar]
What is an isotope?
Calculating average atomic mass:
22. a.Calculate the average atomic mass for silicon if 92.21% of its atoms have a mass of 27.98 amu, 4.70% have a
mass of 28.98, and 3.09% have a mass of 29.97 amu.
b. Calculate the average atomic mass of oxygen. Oxygen has three naturally occurring isotopes: oxygen -16 with a
mass of 15.99 amu an abundance of 99.76%, oxygen -17 with a mass of 17 amu and an abundance of .038%, and
oxygen-18 with a mass of 18.00 amu and an abundance of 0.20%.
The Mole: A Huge Number
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A mole (mol) is = 6.022 x 1023 particles
1 mole is the number of atoms in the atomic mass of an element when the mass is expressed in grams.
Example: carbon-12: 1 mole = 6.022 x 1023 atoms = 12 grams and 1 atom of carbon is 12 AMU
Avagadro's number = The number of particles (or atoms), 6.022 x10 23 in exactly 1 mole of pure substance.
Unit Conversions with Grams, Moles, and Particles
23. How many atoms are present in 3.7 moles of sodium?
24. How many atoms are present in 155 moles of arsenic?
25. How many moles of xenon are equivalent to 5.66 x 1026 atoms?
26. Find the mass in grams of 8.6 moles of bromine atoms.
27. Find the mass in grams of 7.55 moles of silicon atoms.
28. How many moles are in 38 g of carbon atoms?
29. How many moles are in 2 g of hydrogen atoms?
36. What is an ion?
37. What is an isotope?
38. What part of the atom is involved in nuclear reactions? ___________
39. What part of the atom is involved in chemical reactions? ____________
Naming Compounds
59. Name the following compounds.
KBr _________________________
NiCl3 ______________________
P2O3 ______________________
BeF2 _________________________
PbBr2 _______________________
FeO ______________________
AsCl3 ______________________
Na2CO3 _______________________
Cs2S _________________________
H2O _______________________
Formula Writing
60. Write the formulas for the following.
lithium sulfide _________________________
iron (III) oxide ______________________
silicon tetrachloride ______________________
calcium oxide _________________________
barium fluoride _________________________
tin (II) fluoride ______________________
nitrogen dioxide ____________________
iron (II) oxide ____________________
sodium bicarbonate _______________________
zinc oxide _______________________
Calculating Empirical Formulas from Percent Composition
Example: The ingredients of a rechargeable battery has the following percent
composition: 21.9% Oxygen, 1.4% Hydrogen, 76.7% Cadmium
Step 1: Find the moles of each component:
21.9% Oxygen means 21.9 grams in every 100 grams of compound. Molar mass
of oxygen =16g/mole
21.9g x 1 mole O/16g O = 1.4 moles O
1.4% Hydrogen means 1.4 grams in every 100 grams of compound. Molar mass
of hydrogen = 1g/mole
1.4g x 1 mole H/1g H = 1.4 moles H
76.7% Cadmium means 76.7 grams in every 100 grams of compound. Molar mass
of cadmium =112g/mole
76.7g x 1 mole Cd/112g Cd = .68 moles Cd
Step 2: Divide the moles of each element by the moles of the element with the smallest
amount to find a whole number ratio.
0.68 mol Cd/ 0.68 = 1.0 mole Cd
1.4 mol O/ 0.68 = 2.06 mole O
1.4 mol H/ 0.68 = 2.06 mole H
The ratio is 1 Cd : 2 O : 2 H; therefore --------> CdO2H2
69. Calculate the empirical formula from the percent composition. Please show all work.
Fe = 63.6%
S = 36.4%
70. Calculate the empirical formula from the percent composition. Please show all work.
Ni = 52.6%
C = 21.9%
N = 25.5%
25. Express your understanding of the isotopic notation and sub-atomic particles by filling in the table below.
Name
Symbol Atomic# Mass#
# of Protons
# of Neutrons
# of Electrons
aluminum-27 atom
______ ______ ______
______
______
______
sulfur-32 atom
______ ______ ______
______
______
______
lead-208 ion
______ ______ ______
______
______
80
potassium-40 atom
______ ______ ______
______
______
______
7. Find the mass of 5.45 moles of magnesium Please show all your work
8. Find the number of moles of Boron in 83.2 grams of Boron
9. Find the number of moles of argon in 3.85 x 1024 atoms of Argon
10. Find the mass of 0.85 x 10 24 atoms of Phosphorus
11. What is the mass of 0.65 moles of Br2?
12. How many moles are contained in a sample of Ca(OH)2 that has a mass of 100.0 g?
13. What is the mass of 7.75 X 10 24 molecules of H2O?
14. What is the mass of 2.35 moles of C12H22O11?
1. If the mass of a powdered substance is 10.52 kg and the volume is 20.4 L, what is the density
of the powder?
2. If a piece of copper has a mass of 14 grams and a density of 8.94 g/cm3, what is the volume of
the copper?
3. If a sample of ethanol has a volume of 15 mL and a density of 0.789 g/mL, what is the mass of
the liquid?
4. If a liquid has a volume of 32 mL and the mass of the liquid and the graduated cylinder is 104
g, and the cylinder has a mass of 20 g, what is the density of the liquid sample? If I dropped a
solid object with a density of 2.13 g/mL into the liquid above would it sink or float?
5. Three objects all have the same volume. The three objects have different masses. Which of the
objects would have the highest density? The object with the least amount of mass, most amount
of mass, the one with the mass between the smallest and largest volume. Explain your answer.
10.Convert 22 L to milliliters.
11. Convert 23.5 decigrams to kilograms.
12. If a cube has the dimensions of 3 cm , 2 cm, and 5 cm and a mass of .006 kg, what is the
density of the cube in grams/ cm3?
Label each of the following as PC (physical change), CC (chemical change), PP (physical property), or CP
(chemical property).
16. ice melting
21.sugar tastes sweet
17. baking a cake
22.New substances are produced
18.silver tarnishes when exposed to air
23. No new substances are produced
19. hydrogen and oxygen combine to form water
24. A characteristic of a substance
20. the density is 6 g/ml
25. How a substance will react
States of Matter
If you were to draw pictures of the three states of matter at the particle level, identify which description below
describes a solid, a liquid, a gas.
26. _________ The particles would be very organized and close together.
27. _________ The particles would be randomly spaced but close together
28. _________ The particles would be randomly spaced but very far apart from each other