2012-2013 Honors Chemistry Final Exam Review

-Scientific Method

  • Observation:
  • Hypothesis:
  • Experiment:
  • Data
  • Qualitative Data:
  • Quantitative Data:
  • Theory or Scientific Law
  • Theory:
  • Scientific Law:
  • Practice: Identify the parts of the scientific method in the paragraph below.
  • On last week’s episode of Mythbusters, Adam came up with the myth that a person can swim just as fast in syrup as they can in water. Jamie and Adam built two identical trenches and lined them both with plastic. One trench they filled with water, in the other trench, they poured a mixture of guar gum and water so that it had the exact same consistency as maple syrup. Both Adam and an Olympic gold medalist in swimming swam three laps in each pool and were timed by Jamie. Adam’s average time in the syrup was 1 second slower than in the water. The Olympian’s times for swimming in syrup were vastly different for each of the three trials which they later contributed to the thickness in the syrup messing with the swimmer’s technique rather than just his speed. So they threw out the results for the Olympic swimmer and kept only Adam’s results. Both Jamie and Adam concluded that the myth is indeed plausible; you may just be able to swim just as fast in syrup as you can in water.

-Lab Equipment

  • Identify & describe the use for the following pieces of lab equipment.

-Scientific Notation

  • Converting from regular notation into scientific notation
  • Move the decimal point so that it is after the 1st number (So that the number is between 1 and 10) [Ex. 12300.0 becomes 1.23 ]
  • Add “× 10” and then count how many times you moved the decimal point. That will be the superscript on the 10.
  • If the original # was greater than 1 (meaning your moved the decimal point to the left), then the super script will be a positive number. [Ex. 12300.0 becomes 1.23 × 104]
  • If the original # was less than 1 (meaning you moved your decimal point to the right), then the super script will be a negative number. [Ex. 0.00456 becomes 4.56 × 10-3]
  • Practice writing these numbers in scientific notation.
  • 67800
  • 0.0000789
  • 96300000
  • 0.00000085
  • Scientific Notation in Calculations- When adding, subtracting, multiplying or dividing numbers that are written in scientific notation AND you are using a scientific calculator: MAKE SURE YOU USE THE “EE” OR “EXP” BUTTON ON THE CALCULATOR!
  • For example, let’s say you are dividing (1.47 × 105) / (2.58 × 103).
  • You would put this into your calculator…
  • 1.47 EE 5 ÷ 2.58 EE 3 =
  • Practice these calculations with your calculator
  • (3.2 × 10-8) + (5.43 × 10-9) =
  • (8.42 × 1012) × (3.69 × 1011) =
  • (5.46 × 10.6) ÷ 62 =

-Unit Conversions by dimensional analysis- One of the things that many students have problems with is unit conversions. Unfortunately, unit conversions are really important to know how to do.

  • For example, let's say that somebody wants to do a calculation of the number of moles of water in your body. This seems like it should be easy, but you probably know your weight in pounds (if you live in the US) rather than kilograms - since mole conversions are in grams, you need to be able to convert between pounds and kilograms to do this.
  • Fortunately, there's a way around this. It's called the "factor-label method", or the "t-chart method". Whatever you call it, the idea is the same.
  • The idea behind this method is simple. In every problem, they give you a number you need to convert. We'll refer to this as "what you know", since it's the given in the problem. In every problem you're also given something you need to find. We'll refer to this as "what you want to know". When doing conversions between what you know and what you want to know, you'll need to have some unit conversion factors. These factors are along the lines of "there are 12 inches in one foot" - nothing too disturbing.
  • Let's do an example:

Example: Convert 10 meters to inches. There are 2.54 centimeters in 1 inch.

How to solve:

Go through these steps to make your life much easier:

1) Draw a great big T. It should look like this:

2) Put the number the problem gives you to convert in the top left of this T. Since the problem told you that you've got "10 meters", that's what you should write up there. Check it out:

3) Put the unit of that number in the bottom right part of the T. In this case, the unit is "meters", so you just write that in the bottom right. Have a look:

4) Write the unit of what you want in the top right. Now, in this question we may have a problem. Here it is: Do you know what the conversion factor is between meters and inches? Come on, off the top of your head! Quick, what is it? What do you mean you don't know?

Well, we have a problem then. If you can't convert between meters and inches, I guess you can't do the problem. It's unsolvable!

Or is it?

Maybe, just maybe we can convert meters to something that can be converted to inches. If we're really lucky, the question might give you a hint as to what you can try. Let's take a look at the question again:

Example: Convert 10 meters to inches.There are 2.54 centimeters in 1 inch.

I don't know about you, but I just had an idea! Maybe instead of going directly from meters to inches, we could go from meters to centimeters, and then from centimeters to inches! I'm a genius!

As a result, we'll put the unit "centimeters" in the top right.

5) Write the unit conversion factor in front of the units from steps 3 and 4.

There are three ways to do this:

  • Sometimes the unit conversion factor is so simple that it doesn't need to be told to you - it's assumed that you know it off the top of your head. Examples of this include the factors "12 inches in 1 foot", "3 feet in 1 yard", "60 minutes in 1 hour", "24 hours in 1 day", and so on. If this is the case for a problem, then all you need to do is look back in your memory to figure it out.
  • When the unit conversion factor isn't simple, the problem will give it to you. For example, in this problem, the problem tells you that there are 2.54 centimeters in 1 inch. That'll probably come in handy, and is obscure enough that you don't need to memorize it.
  • When converting from metric units to other metric units, you put a "1" in front of the unit with the prefix, and write the "multiplier" in front of the unit without the prefix. The common multipliers for metric conversions are as follows:

Prefix / Multiplier
micro / 0.000001 (10-6)
milli / 0.001 (10-3)
centi / 0.01 (10-2)
deci / 0.1 (10-1)
kilo / 1,000 (103)
mega / 1,000,000 (106)
giga / 1,000,000,000 (109)

In this problem, that's what we need to do because we're converting between meters and centimeters. Since "centimeters" has a prefix (centi), we write a 1 in front of it. Since "meters" has no prefix, we put the multiplier for centimeters in front of it. From the chart above, we can see that the multiplier is 0.01. Let's do it!

6) If you're not done with the conversion in one step, draw another vertical line in the t-chart after the first step and start over at step 3. I'll assume that you can follow along with what we're doing at this point, so I'll just show you the steps you need to follow in a bunch of different diagrams. If you have problems following what we're doing, refer to the steps above.

Here's what it looks like when you draw the vertical line and stick the unit in the bottom right (from step 3):

Since we want to convert to inches and we have a unit conversion factor between centimeters and inches, write inches in the top right:

Since we know that the unit conversion factor between inches and centimeters is "2.54 centimeters in 1 inch", write "2.54" in front of centimeters and "1" in front of inches:

7)Since you've got the t-chart filled out, all you have left to do is multiply all the numbers on the top together and divide them by the product of all the numbers on the bottom. The unit of this answer will be "inches", since "meters" and "centimeters" cancel out. As a result, we get:

And that's your answer! Yeeeeha!

  • Practice Problems to Try
  • Convert 52.6 g to mg
  • Convert 9.63kg to mg
  • Convert 1234mg to Mg

-Density – Density is the ratio of mass to volume of a substance. Water, a universal substance, has a density of 1.00g/mL. Substances that have a density less than water does float in water. Those substances that have densities greater than water’s sink in water. Density of regular, cube shaped objects can be determined by first, finding the mass and the finding the length, width, and height of the object and using those measurements to find the volume. (V = l × w × h). If you have an irregularly shaped object that is not soluble in water, you can find the volume by water displacement. Fill a graduated cylinder with water and record the volume, then carefully place the object in the water and record the new volume. The volume of the irregular object is the difference between the two volumes. (Vobject = Vwater & object – Vwater)

  • Equation for density d = m/V
  • Problems to try
  • A student finds a rock on the way to school. In the laboratory he determines that the volume of the rock is 22.7 mL, and the mass in 39.943 g. What is the density of the rock?
  • What is the mass of a 350 cm3 sample of pure silicon with a density of 2.336 g/cm3?
  • A strange object is found to have a mass of 0.582g and its volume was found by water displacement. A graduated cylinder was filled to volume of 33.4mL and the object was carefully placed in the graduated cylinder and the new volume was read to be 36.5mL. What is the density of the object?

-Temperature Conversions- There are 3 temperature scale of which you should be aware: Fahrenheit, Celsius, and Kelvin. You will need to be able to convert between the 3 scales.

  • To convert between Celsius and Kelvin
  • T°C = TK – 273
  • TK = T°C + 273
  • To convert between Celsius and Fahrenheit
  • T°C = .56(T°F - 32°)
  • T°F = 1.8(T°C) + 32°
  • Practice problems
  • Convert 98.6°F to °C and then to K.
  • Convert 4K to °C and then to°F

-Matter

Matter

Pure SubstancesMixtures

Cannot be separated physicallyCan be separated physically

ElementsCompoundsHeterogeneousHomogeneous

Only 1 kind of 2 or more atomseach component is (solution) uniform

atomchemically bondedvisiblecomposition

Separating Mixtures

-by hand

-magnets

-filtration

-chromatography

-distillation

Properties of Matter

Physical PropertiesChemical Properties

-can be identified without changing -can be identified when the

the substancesubstance changes

Ex. Shape, color, melting point, boiling point,Ex. Flammability, digestion,

density, texturedecomposing, fermenting, rusting

  • Try these
  • Identify the following as an element, compound, heterogeneous mixture, or homogeneous mixture.
  • Air
  • Dirt
  • Silicon
  • Hydrogen
  • Coffee
  • Carbon tetrachloride
  • Identify the following as physical properties/ changes or chemical properties. Changes.
  • The substance is silver.
  • It catches on fore when placed in water.
  • Its density is 10.52g/mL.
  • It develops a white crust when exposed to air.

-Atomic Theory

  • What is the importance of the following people, experiments or models to the development of our current theory of the atom?
  • Democritus & Aristotle:
  • The Alchemists:
  • John Dalton:
  • Dalton’s Atomic theory:
  • J.J. Thomson:
  • Cathode Ray Experiment:
  • Plum Pudding Model:
  • Ernest Rutherford:
  • Gold Foil Experiment:
  • Neils Bohr:
  • Planetary Model of the Atom:
  • Erwin Schrödinger:
  • Wave Mechanical Model:

-Atomic Structure

  • What subatomic particles reside inside the nucleus of an atom? Outside the nucleus?
  • Explain what an electron cloud is.
  • What are the charges for protons? Neutrons? Electrons?
  • What is atomic number? Mass number?
  • What is atomic mass?
  • Isotopes
  • Atoms of an element that have the same # protons BUT different # neutrons.
  • Symbol
  • Determine the # protons, # electrons, and # neutrons for each isotope below.

-Periodic Table

  • Can you identify the following parts of the Periodic Table?
  • Groups
  • Periods
  • Metals
  • Nonmetals
  • Metalloids
  • Alkali metals
  • Alkaline earth metals
  • Halogens
  • Noble gases
  • Transition metals
  • Inner transition metals

  • Periodic Trends
  • Atomic/ Ionic radius-
  • As you move from left to right across a period, what happens to the general size of the atoms?
  • As you move from top to bottom down a group, what happens to the general size of the atoms?
  • Ionization energy – energy needed to remove an electron from an atom
  • As you move from left to right across a period, what happens to the ionization energy of the atoms?
  • As you move from top to bottom down a group, what happens to the ionization energy of the atoms?
  • Electronegativity – the attraction an atom has for other atom’s electrons
  • As you move from left to right across a period, what happens to the electronegativity of the atoms?
  • As you move from top to bottom down a group, what happens to the electronegativity of the atoms?

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