General Chemistry - Unit 1
Dimensional Analysis Tips There are three steps to solving problems: 1. Find where to start: write down the variables in the problem separately. This allows you to easily see important information. 2. Find the ending: write down what variable you are finding. 3. Develop a plan to find the answer: this is where you lay out the steps to get from start to end and is the hardest part. The next slide contains an example.
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LOOK AT THE MATTER CHART AND HOW IT BREAKS UP INTO 2 SECTIONS
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The diameter of a mitochondrion is about 1.2 ✕ 10−4 in. What is its diameter in centimeters? 1 inch = 2.54 centimeters
.0003048 > .00030
A person weighs 175 lb. What is the daily dosage, in grams, of a prescribed medication for this person if the recommended dosage is 10.0 mg drug per kilogram of body weight? (1 lb = 453.59237 g exactly)
.794
How many kg is in a g? How many pg is in a g?
1 kg = 1000 g 1x10^12 pg = 1 g
If you had 8.64e+23 silver atoms, how many moles of silver would you have?
1.43
Imagine an element with the letter S in the middle and in the top left corner has the number 33 whereas the number in the bottom left corner is 16... What's the atomic mass / it's the number of _______ what's the mass / it's the number of ____ the number of _______ How many neutrons are in it? & name the "equation" to find the neutrons
16 / protons / atomic number 33 / protons + neutrons neutrons = atomic mass - atomic number = 17
a) How many moles of CO2 contain 2.11 ✕ 10^24 molecules? b. What number of moles is equivalent to 7.29 ✕ 1021 atoms of Hg?
3.50 mol CO2 .0121 mol Hg
How many molecules of galactose (C6H12O6) are present in 24.1 g of the substance?
8.06 x 10^22
What does an atomic symbol look like? *Where does the charge of an ion go
A X Z where X is the elemental symbol, A is the atomic mass, and Z is the atomic number (number of protons) If charge is needed because it is an ion, it will go on the upper right. Many times, the atomic number will not be shown.
What's the difference between accuracy and precision? Describe these 3 samples of pouring a 10.0 mL solution: a. 9.9, 9.8, 9.9, 9.7 b. 8.5, 8.7, 8.6, 8.5 c. 9.1, 9.9, 8.3, 8.6
Accuracy is how close a measurement is to a true value, and precision is how close measurements are to each other (not compared to the true value a. Precise and Accurate b. Precise but NOT Accurate c. NEITHER
Summarize the postulates of Dalton's atomic theory. (I) All matter is made of ---Select--- atoms molecules , which are tiny and indivisible. (II) All atoms of a given element are ---Select--- different identical , and atoms of different elements are ---Select--- different identical .(III) Chemical reactions ---Select--- can cannot create or destroy atoms, and they ---Select--- can cannot change atoms of one element into atoms of another element. (IV) A compound is a combination of two or more different types of atoms. The ratio of one type of atom to another in a given compound is ---Select--- fixed variable and can be expressed as a ratio of small whole numbers
Atoms Identical / Different Cannot destroy / Cannot change Fixed
What is the difference between base units and derived units?
Base units are standards that are set that are not calculated from other base units. Derived units are calculated from the base units (for example, density = mass/volume).
Convert the following numbers to proper scientific notation. (a) 33500 (b) 235.00 ✕ 10^3 (c) 0.0000529 (d) 0.0063 ✕ 10^-4
CHECK PAPER
Classify each of the following changes as physical or chemical. (a) baking bread physical chemical (b) scratching a wooden floor physical chemical (c) distillation of vinegar
Chemical - chemical reactions w/ yeast Physical Physical - evaporating and condensation and whatnot is used
What's chemistry?
Chemistry is the study of matter. We will learn about how the properties of substances and substances themselves change
An ibuprofen suspension for infants contains 80 mg/mL. The recommended dose is 10 mg/kg body weight. How many mL of this suspension should be given to an infant weighing 21 lb? Given: suspension = 80 mg/mL Dose = 10 mg/kg Infant weight = 18lb Find: dose for 21 lb infant
Conceptual plan: lb → kg → mg medicine → mL suspension
What's the formula for density?
Density = mass / volume
What is dimensional analysis? Any tips to help?
Dimensional analysis is a series of unit conversion needed to solve a problem. A lot of chemistry is changing measurements from one unit to another using a ratio called a conversion factor Sanity check your answers! Think about what it should be so you're on the right track. If you're converting from meters to inches, then your answer must be larger than the number you converted. If it isn't, you know you've done something incorrectly.
Ions are when _______ are moved around Isotopes are when ______ are moved around
Electrons / Neutrons
What's the property when: *changes depends on the amount of stuff changes changes as the size of the substance changes For example, if you compare a cup of water to a liter of water, the mass will be different
Extensive Water bottle = a certain size (48 ounce) Associated length and volume If bottle expands or doubles in size magically, it would hold 96 ounces, and be 2 ft tall Water bottle changes in volume as it changes
List all the extensive (6)
Extensive properties include: volume / mass / size weight / length
What's "scientific thinking"? (4 steps)
First, you make an observation and wonder why. o Next, you propose an explanation for the observation. o Then, you run some experiments to see if your explanation makes sense. o If your explanation doesn't make sense, you propose another explanation. If your explanation does make sense, more work is done to see if it is true all of the time. If your explanation works under a lot of conditions, a theory could be developed. If the original observation you made happens all of the time, a law could be described
Phase: Gas Volume and shape? Motion? Density? Compressibility?
Gas Volume and shape conforms to the container / is the container's bitch PARTICLES ARE IN CONSTANT MOTION A A . A A A A SLIDING PAST ONE ANOTEHER Low density Easy to compress
Some ---Select--- hypotheses laws theories scientific methods are attempts to explain the behavior that is summarized in a ---Select--- hypothesis law theory scientific method , which describes or predicts some facet of the natural world.
Hypothesis / Laws
State whether each number expressed in the following statements are exact or inexact numbers. (a) The scuba diver's diving cylinder has a pressure of 3000 psi.The number is ---Select--- exact inexact (b) The dumbbell has a weight of 50 pounds.The number is ---Select--- exact inexact (c) There are 13 states that border Canada.The number is ---Select--- exact inexact (d) The movie theater has a seating capacity of 200 persons.The number is ---Select--- exact inexact .
Inexact Inexact Exact Exact **Exact is when it's EXACTLY this -- is absolutely definite whereas inexact is usually a measurement
What's the property when: *"it being it" - does not change based on the stuff tdoesn't change as the size of the substance changes For example, the boiling point of a cup of water is the same as the boiling point for a liter of water.
Intensive Density of water = 1 gram per mm - does not change Does not change when it's swimming pool or a cup of water Specific heat capacity doesn't change - how much heat something can hold Property of itself of what it is Temperature - doesn't matter how big or small it is - you can have it as a certain temp All are properties of IT Molecules themselves (composition) = what atoms and elements make up of it = H2O
List all the intensive (7)
Intensive properties include: boiling point / color / temp / luster / density / hardness
What is an exact number? For example, 1 dozen = exactly 12 of something. 1 cm = exactly 2.54 cm.
It is a conversion with an exact definition. Exact numbers are also for a thing you can count You can count how many of an object is in front of you, so there is no question how many there are
Why are prefixes like centi, milli, etc. important? For example... 8 gigabytes than 8,000,000,000 bytes
It's much easier to deal with certain numbers. For example, it's easier to do math with 8 gigabytes than 8,000,000,000 bytes. As long as you know the order of magnitude represented by the prefix, you're good to go for when you need to convert units
What's the formula for both Kelvin and Celsius? What about fahrenheit, given celsius? What about celsius, given fahrenheit?
K = C + 273.15 C = K - 273.15 F = 9/5C + 32 X = 5/9F - 32
The whole-number mass ratios of the components is the law of... Lastly, we determine the whole-number ratios of the mass ratios is the law of ________ ________
Law of definite proportions multiple proportions
Exactly one pound of bread dough is placed in a baking tin. The dough is cooked in an oven at 350°F, releasing a wonderful aroma of freshly baked bread during the cooking process. Is the mass of the baked loaf greater than, less than, or the same as the one pound of original dough?
Less The mass would be less than one pound as water vapor and other molecules (aroma) are released from the cooking dough.
Phase: Liquid Volume and shape? Motion? Density? Compressibility?
Liquid Fixed volume BUT SHAPE IS IN THE SIZE OF CONTAINER Atoms or molecules are CLOSE TOGETHER, but can still move around in an disordered way MODERATE DENSITY minor smoosh/compress
A lead pipe is: _______ domain A bromine atom is: ______ domain
Macroscopic Microscopic
Observations are made with (3) things:
Macroscopic Domain Microscopic Domain Symbolic Domain
Why are some numbers not considered exact numbers? How does this relate to significant figures?
Many things must be measured with some sort of instrument (rulers, scales, etc.) You're always guessing about the measurement to some extent Each instrument has an associated uncertainty. This lets you know how accurate the device is. A ruler that has an uncertainty of 0.01 cm is more accurate than one that has an uncertainty of 0.1 cm. The number of significant figures is based on the uncertainty in the device and tells us how accurate the measurement is.
Matter Chart: What's the: Has mass and takes up space IF IT CAN BE PHYSICALLY SEPARATED it creates a: __________ _________ which is when "the sample is made of different stuff" IT BREAKS DOWN INTO 2 SECTIONS: > _____________: Every part of the sample looks the same >____________: Parts of the sample look different
Matter Mixture Homogeneous Heterogeneous
Matter Chart: What's the: Has mass and takes up space IF IT CAN'T BE PHYSICALLY SEPARATED it creates a: __________ _________ which is when "the entire sample is made of the same stuff" IT BREAKS DOWN INTO 2 SECTIONS: > _____________: THE SAMPLE ONLY CONTAINS ONE TYPE OF ATOM >____________: THE SAMPLE ONLY CONTAINS MOLECULES
Matter Pure substance Element Compound
What is uncertainty?
Measurements involve instruments and humans, and both of those can contribute to errors. The uncertainty is the amount of error (or a description of how good the measurement is)
Find the molar mass of MnSo4? How many moles are in 131 grams of MnSo4?
Mn (54.94) + S (32.07) + O4 (64) = 151.01 g/mol 1 mol = 151.01 g/mol 131/151.01 = .867
How to solve for the atomic mass if given mass (amu) and abundance (%)?
Multiple mass and abundance[move the % two decimal places to the left], and then add all of the numbers together at the end
What's a law?
Of science summarize a vast $ of experimental observations, and describe or predict some facet of the natural world
Define: precision accuracy w/ archers
Precision: when they hit the target in roughly the same spot every time (precise aim/spot) Accuracy: when they actually hit it in the middle/where they're supposed to
Write the symbol for each of the following particles. (a) an atom with 16 protons and 16 electrons S (b) a magnesium atom that has lost 3 electrons Mg3+ (c) an iodine atom that has gained 1 electron I1- (d) an oxygen atom with 9 neutrons in its nucleus (Enter your answer using the format AX.) O17
S Mg3+ I1- O17
Phase: Solid Volume and shape? Motion? Density? Compressibility?
Solid Fixed volume AND shape atoms or molecules vibrate in a fixed position relative to one another High density Difficult to compress/smoosh
What's a hypothesis?
Tentative explanation of observations that acts as a guide for gathering and checking info Tested via experiment, calculation, or comparisons w/ others
If a law works it creates a .... Scientific theory.. which is:
That are well-substantiated comprehensive, testable explanations of particular aspects of nature (accepted because of the explanations)
What is the macroscopic domain? Give an example!
The macroscopic domain is the big stuff; we can see that directly. Macroscopic Domain: anything we can see with our eyeballs Tables, eraser, rubberband, and basically anything
What is symbolic domain? Give an example!
The symbolic domain is how we represent substances using symbols or pictures. It allows us to share information with others. Symbolic Domain: how we represent stuff Chemical symbols, pictures, drawings, diagrams, graphs, etc...
When magnesium burns in air, a white flaky ash of magnesium oxide is produced. Is the mass of magnesium oxide greater than, less than, or the same as the original piece of magnesium?
The mass of the magnesium oxide product would be greater than the original magnesium metal as the amount of magnesium remains the same, but having combined with oxygen, the total amount of matter increases.
Antoine Lavoisier, the French scientist credited with first stating the law of conservation of matter, heated a mixture of tin and air in a sealed flask to produce tin oxide. Was the mass of the sealed flask and contents after heating greater than, less than, or the same as the original flask and contents?
The mass of the sealed flask and contents would remain the same as no reactants or products leave the flask, and therefore the quantity of matter in the flask does not change.
Why are there so many rules for significant figures? When in doubt, report your answers in __________ ________. Many times, zeros are used as _____________, and are not significant. Scientific notation removes that Do significant figures always matter?
The rules come from the statistics: what happens when we add/subtract numbers or multiply/divide numbers. Scientific Notation / Placeholders Yes, but the number you need changes based on what you're measuring. If you're estimating the mass of something that is very large, you probably don't need to go to 5 decimal places to do that. However, if you're brewing coffee (one of your instructor's favorite morning activities) and the taste changes if you're off by 0.1 g of coffee, then you'll want a scale that measures to at least 0.1g or even 0.01 g.
If a hypothesis can explain a large body of experimental data, it can reach the status of a ---Select--- hypothesis theory law scientific method , which is a well-substantiated, comprehensive, testable explanation.The path that leads from questions and observations to laws and/or theories is called the ---Select--- hypothesis law theory scientific method .
Theory Scientific Method
What's the scientific method? Simple definition
This is the process of science.
Why do we need a standard set of units for reporting measurement of properties?
This makes it easier for scientists to talk to each other. When measurements are reported the same way by everyone, it's easy to understand what is being reported.
Why are unit charge and amu used?
Whole numbers are easier to work with than very small exponents, and we can convert when necessary.
How many significant figures are contained in each of the following measurements? (a) 0.39 g (b) 4 ✕ 10^13 m (c) 9.701 ✕ 10^−3 J (d) 0.00635 cm3
a. 2 b. 1 c. 4 d. 3
Sucrose, or table sugar, is a common food sweetener. It is composed of carbon, hydrogen, and oxygen in fixed proportions, regardless of the source from which it is obtained. Also, sucrose, carbon, hydrogen, and oxygen all have their own distinct sets of properties. Given this information, classify each of the following types of matter as a pure substance, element, compound, homogeneous mixture, or heterogeneous mixture. Please note that more one than classification may apply to each. (a) Sucrose is a ---Select--- heterogenous mixture homogeneous mixture pure substance that is ---Select--- a compound an element . (b) Carbon, hydrogen, and oxygen are ---Select--- heterogenous mixtures homogeneous mixtures pure substances that are ---Select--- compounds elements (c) Sucrose that is totally dissolved in water is a ---Select--- heterogenous mixture homogeneous mixture pure substance (d) Sucrose that is only partially dissolved in water is a ---Select--- heterogenous mixture homogeneous mixture pure substance .
a. Pure Substance Compound b. Pure substances / Elements c. Homogenous d. Heterogenous
What is: When a _________ ________ changes, the identity of the stuff changes. When iron metal reacts with oxygen, it forms rust, which is a new compound. Measuring ________ _________ changes the identity of what we're observing.
chemical property
What is: It is something that can change without changing the identity of the stuff. For example, if ice melts, it's still water. We can also observe or measure them without changing the identity of what we're looking at
physical property
Identify SI Units Give the name and symbol of the prefixes used with SI units to indicate multiplication by the following exact quantities. (Use the letter "u" in place of "µ" if needed.) (a) 10^−12 name symbol (b) 10^9 name symbol (c) 0.000001 name symbol (d) 0.01 names ymbol
pico / p giga / G micro / u centi / c
Write the protons, neutrons and electrons: atomic number 43, mass number 99, charge of 7+
protons 43 neutrons 56 electrons 36
The mass number of a xenon (Xe) isotope is 112. Compute the number of protons, neutrons, and electrons in a neutral atom of this isotope, and write the symbol for the isotope using the notation AZX. (a) Compute the number of subatomic particles in a neutral atom of this isotope: protons neutrons electrons (b) Write the symbol for the isotope using the notation AZX.
protons 54 neutrons 58 electrons 54 112 mass - 54 protons (atom #) = 58 neutrons ^112_54 Xe 112 = mass number 54 = atomic number
What's the Law of Conservation of Matter?
the amount of matter doesn't change when a substance or phase changes. You've probably heard that matter can't be created or destroyed
What is the microscopic domain? Give an example!
which is the stuff we can't see directly. Special tools are used to measure these properties. Microscopic Domain: things we can't see unless it's with a microscopic/tool Cells, smaller, small things that can't be seen with the naked eye
Go in your notes and look at the questions that was given on Webassign for 1.1-1.3!
yes.
