SciHawks

Physics- we analyzed a speed vs time graph, noting when acceleration was positive, negative, or zero (each acceleration was uniform, as indicated by the lines as opposed to curves on the graph). We then calculated the distance traveled for each separate segment of the graph, sometimes having to split the shape under the curve into a right triangle and a rectangle. For right triangle sections ONLY, be careful to always divide the base x height product by 2.

We then sketched the distance vs. time graph, noting that when speed vs. time is a straight, positively sloping line, the distance vs. time graph looks like half of a "smiling" PARABOLA. When the speed vs. time graph is a flat , zero slope line, the distance vs. time graph is a POSITIVELY sloping STRAIGHT line (assuming positive velocity).
Overall, the slope at any given point on the distance vs. time curve IS THE SPEED of the object at that point!
The slope at any given point on the speed vs. time curve is THE ACCELERATION of the object at that point.
We then started a motion problem in which we had two moving objects. We just wrote the truth: the distance = avg. speed x time for each train and added these distances to equal the total distance given.

Physics - did Motion Ditto 3 problems in which we encountered our first TWO STEP problem. Sometimes, based on the DATA GIVEN right in the question, you will have to solve for ONE unknown variable (usually time, but in this case, acceleration). Once you solve for that unknown, you plug that answer into a different equation to solve for the variable that was asked for.
TWO STEP problems are more difficult, naturally, so we will practice more of them soon.

We then did our first graphical analysis of motion lab in which we analyzed the motion of a cart via a click-timer.

AP Chem - HERE IS A LIST OF THE QUESTION TYPES ON TOMORROW'S EXAM:

1. Write and balance (including phase labels) the formula, ionic, and net ionic equations for
a. double replacement with precipitation reactions
b. double replacement acid-base neutralization reactions

2. Percent composition to empirical formula to molecular formula problems
and/or the REVERSE.

3. Determination of atomic mass from isotope masses and respective percent abundances
and/or the REVERSE.

4. Combustion analysis to determine the empirical formula and molecular formula of an organic compound.

5. Gravimetric analysis to determine the atomic mass of an unknown element in a compound.

There are NO questions on our current STOICHIOMETRY unit.
Also, I will not ask about the FOUR separation of mixture techniques BUT I will have questions about those techniques on an upcoming quiz or future test.


STUDY THOROUGHLY by reviewing/copying NOTES and doing practice questions.


Email me if you have questions or see me at extra help at 8AM in Room 306 on Thursday.

Today we applied limiting reactant stoichiometry to the reaction for the synthesis of urea. We determined the masses consumed and produced for all substances by first converting all masses to MOLES, and then using the mole ratios from the balanced equation.
We also determined and explained percent yield. 

update 8:45 PM - just posted the questions and answers to the equation writing hw from a few weeks ago - just another resource for the exam preparation.

Physics - we did ditto 2 from the straight-line motion packet, and then analyzed graph II, again relating the speed vs. time graph to a distance vs. time sketch for the same object's motion.

AP Chem - started our new unit on Stoichiometry. We discussed the MEANING of the coefficients of a BALANCED chemical equation in terms of MOLES of atoms, molecules, formula units of the various types of substances.
We then, by analogy, showed that when reactants are not mixed PROPORTIONALLY to their "recipe" amounts, an excess of one reactant remains; the other "limiting" reactant, determines the quantity of each product formed.

We showed the ONLY MOLE RATIOS can be used in determining limiting and excess reactants.
We defined the term "mole of reaction".
We then introduced our percent composition of a hydrate lab, noting proper weighing technique and some sources of error.

Physics - we looked at the equations that relate the various variables of motion: speed, distance, time, and acceleration.
We then applied these formulas, using specific test-taking skills of LABELLING the variables DIRECTLY in the question. We then look up the equation that contains ALL of the variables. We then plug in the data, and solve for the ONE unknown variable.
That is how we solve ALL of these one-step problems.

We then did a graphical analysis of motion. We saw how to get the distance travelled by an object by calculating the AREA UNDER THE LINE (ALL THE WAY down to the x axis) in the SPEED vs. TIME graph. To do so, we use the area of rectangle = bh and area of right triangle = bh/2 formulas.

AP Chem - did TWO gravimetric analysis problems, one in which we used the MOLE method, and the other in which we used the gram/mass method.
We also looked at and reviewed the combustion analysis setup.

Physics - Unit 1 test grades will be posted on Blackboard after 9PM (or a wee bit later).
We went over a couple of multiple choice question and found an answer key error- that boosted the class average by 5% :) Most students got 2 or 3 wrong out of the 20 multiple choice questions - pretty good overall.

We showed the difference between speed and velocity. We discussed the basic motion formulas involving time, distance, speed, and acceleration.
We tried to get a feel for the formulas and a sense of their meaning, particularly the formula for acceleration. We noted that any change in a variable is the difference between the FINAL quantity minus the INITIAL quantity.
We will do problem solving and graphical analysis. We will also collect and analyze lab data to see the relationships in the motion formulas.

AP Chem - now posted on Blackboard is the update data and solution to the para-cresol combustion analysis problem.
We did a percent composition to formula of a hydrated salt, noting that this time the mole ratios of formula units of the salt to molecules of water are the COEFFICIENTS in the formula. The (unwritten) coefficient of the salt part of the formula is almost always "1".

We then did a combustion analysis problem. Be sure to use an excess of significant figures in each step so that rounding errors are not multiplied throughout (this could lead to a wrong answer).

We then did a gravimetric analysis problem in which an unknown sulfate salt of known empirical formula is reacted/precipitated for the sulfate. Using the "gram method" or the "mole method", the unknown cation can be identified.
We went through the process of determining the empirical formula and molecular formula of a compound via combustion analysis.
Our unit exam is on Thursday. On Blackboard, there are many problems and tutorials with which to get additional practice. (Do NOT do the limiting reactant or percent yield problems yet; they are not on the test).

Physics - took our first unit exam, both parts. I'll have your multiple choice results for you tomorrow.
We will continue unit 2, straight-line motion, tomorrow. This unit involves determining distance, speed, and acceleration of objects and can be applied to a practically infinite number of life situations.

AP Chem - did a more complex percent composition to empirical formula problem involving a three-element compound. We reviewed each step, the meaning of empirical formula, and the limits to rounding the decimals in the calculations. (5th period also did atomic mass percent abundance problems that were covered in the 11th period class).

Physics - the emergency lockdown drill pre-empted our multiple choice exam so we will take both parts of the exam during the double period tomorrow.
Be prepared to work and check your answers for at least 70 of the 85 minutes of test time. I will collect the test only after the 70 minute mark, though I will usually collect a test only at the end of a period. Part of good test-taking skills is to assume that you made a few careless mistakes during your first run-through of an exam, and then to find and correct them. Do not change an original answer unless you KNOW that you misread the question or made some other clear-cut error.
You'll find this practice can only help you and never hurt you.
Thanks.

AP Chem - we discussed the basis of atomic mass and did isotope calculations (to be done first thing in 5th period tomorrow); we then did percent composition problems and looked at the "magic triangle of moles, grams, and liters (any condition).
We really got into quantitative AP Chem by figuring out how to go from percent composition to empirical formula. We will do more of those problems tomorrow.

Physics- NOTE: practice problems and the complete answers to the Unit 1 Vectors packet will be scanned and posted on Blackboard by about 8 tonight (if not sooner).  are now posted. Compare your answers to these posted answers, and let me know if you have any questions.

we had extra help this morning - good practice for the exam on Wednesday (3rd period, multiple choice) and Thursday (3rd period, written response).

We went over vector addition, getting the maximum and minmum resultant from any pair of vectors.
We reviewed the graphical and mathematical methods for resolving vectors into their horizontal and vertical components, as well as for vector addition.

We did some vectors 5 problems and a few multiple choice practice problems - check answers on Blackboard later.
Study and be confident tomorrow.

AP Chem - we discussed percent composition (by mass) and applied this formula to the percentage mass of water in a hydrated salt (we'll get to this tomorrow in 10th/11th period - today we caught up on separation techniques and how/why they work; we also discussed the basis of Avogadro's Law).

Physics - EXTRA HELP tomorrow morning (and after school, if desired); to prepare for this week's test, bring questions from the end of the packet that you find difficult.

We discussed the lab write-up: good news that most of you consistently put the unit of each of your measurements- that will always be a good and necessary part of your correct answer.
Some of you did not heed the warning about the misused term experimental "error"- that NEVER means "mistake" in science. When a scientist makes a mistake, the experiment is ruined- it is never written up or published.
Experimental "error" REALLY means "SOURCE of random variation/ uncertainty". That is, an experiment done PERFECTLY by you or a perfect robot/droid STILL will have variation in the EXACT same measurements each time the SAME experiment is performed. Scientists must acknowledge, think about, and MINIMIZE sources of uncertainty in a given experiment. The FEWER sources of uncertainty, the BETTER the experimental design, and the more precise the results can be.

We went over the two hw problems and then did a problem in vectors 5 that shows the MAXIMUM and MINIMUM resultant magnitudes from adding any two vectors: the max is the sum of the two magnitudes ( zero degrees between the two vectors) and the minimum is the DIFFERENCE of the two magnitudes (180 degrees between the two vectors); the resultant can be ANY magnitude between the maximum and the minimum, depending on the angle between the two vectors.

We will finish up vectors 5 tomorrow and then do some test prep for the exam on Wednesday (part 1, multiple choice) and Thursday (part 2, written response).
The questions will closely match those from the packet and the labs; of course the numbers will be different, and the wording of the questions can vary- but that won't be a problem if you always DRAW a picture of what is in the question, and properly label everything with the correct sign and arrow direction.

AP Chem - we did some double replacement equation writing, including acid-base neutralization. Remember, all weak acids are written as un-ionized molecules, which almost ALL of them are (in solution).

We did a few percent composition problems, and then explained how the law of multiple proportions was discovered and applied to determining empirical formulas of compounds.

Physics - the weekend HW, which I will check on Monday,
is to do the problems in Vectors 4 that we did not cover in class:
That is, questions 1 and 2.You can try question 4, but we will do that question together in class.
Our first unit test will be given next Wednesday (Part 1, multiple choice) and Thursday (Part 2, written response).
You can start practicing for the test by doing the multiple choice exam questions at the end of our unit 1 vector packet.

We saw how to calculate the angle of the resultant relative to a given axis; we did so by taking the inverse tangent of the ratio of the opposite side to the adjacent side of the right triangle that forms the resultant.
We the did two types of problems in vectors 4:
1. Resolving a given vector into its horizontal (x) and vertical (y) components.
2. Adding two or more vectors by resolving each vector into its horizontal (x) and vertical (y) components, and then by separately adding these horizontal and vertical components.
We use these sums and pythagorean formula to get the magnitude of the resultant;
then we use the inverse tangent formula to get the angle of the resultant.
Overall, we saw the EXTREME IMPORTANCE of :
DRAWING a sketch of the information in the question so that you have a good idea of what the correct answer should look like
and
LABELING all positive and negative signs and directions
and consistently WRITING UNITS for each quantity.

Keep practicing this method to be confident that you are setting up these problems correctly.
Writing and plugging in the given formulas will be the easier mechanical part.
Have a great weekend.

AP Chem - we discussed the classification of every type of matter, noting the difference between substance and mixture, element and compound, and compound and mixture.
We discussed the basis for the four common techniques used to separate mixtures (11th period was truncated, so I will discuss that with you all on Monday).

We began our new mostly quantitative unit by discussing the basis of the law of constant composition (in compounds).
I posted some Classification of Matter worksheets with answer keys in the Unit 1 Files section on Blackboard.
Do those worksheets and then check your answers.

Physics - introduced the mathematical/trigonometric method of adding vectors via resolving them into their horizontal and vertical components; we then use pythagorean formula to determine the length of the resultant, and the tangent formula to determine the direction/angle of said resultant.
With some practice, we will be able to solve hundreds of "seemingly" different problems that all just involve vector addition.

The map displacement lab is due tomorrow, Friday, in class.
I had extra help this morning, as posted and announced, to help anybody who had questions about the lab.

AP Chem - CHECK OUT Blackboard. I posted some very good review tutorials on ions vs. molecules, compound naming and formula writing, as well as a worksheet with key on these topics. There's also the promised animation of an ionic compound dissolving in water.
We did some double-replacement with precipitation equation writing, using the formula, ionic, and net ionic equations.
We then did a qualitative analysis lab in which we applied our knowledge of solubility rules, formula and equation writing to deduce a set of unknown solutions based on the reactions observed.

Physics - looked at the big picture of graphically adding vectors by just sketching some vectors from data in a question. This way, you can get a quick estimate of what your more accurate answer should look like at the end of your measurements.

We then applied the graphical method of vector addition to a displacement mapping lab.

AP Chem- explained the cause of solubility rules via Coulomb's Law. We discussed the CAUSE of the strength of a given ionic bond between a cation and an anion, and also the ATTRACTIONS between water molecules and ions.

Physics - we finished Vectors 2 problem 1, using a new scale so that the vectors fit on the graph.

We then did problem 4, though we didn't get to measure the angle of the resultant. I measured the angle and posted that in the notes on Blackboard.

We will finish the graphical method of combining/adding vectors, and then move on to the more accurate mathematical/trig method (remember SOH-CAH-TOA ? good.)

AP Chem - we finished contrasting molecules and ionic compounds, drawing samples of separate molecules (which NEVER bond together) and then drawing samples of ionically bonded (on ALL sides) cations and anions in a salt's lattice.

We went through the logic of the periodic table to show that KNOWING the charge of a given representative metal cation or nonmetal anion is easy to reason, given the "octet rule" and the knowledge of its cause.

We discussed the test a bit, and then did some sample compound naming and drawing problems.
We discussed the setup of our solubility rule, qualitative analysis lab.

Physics - we compared and contrasted scalar and vector quantities. The main difference is that vector quantities, in addition to a magnitude, have a specific DIRECTION, e.g. 25 mph 20 degrees west of south (or 70 degrees south of west).

We then saw how to draw vectors, how to calculate a proper graph scale, and also how to graphically add vectors, doing the vectors 1 problems in the packet. I will scan a post the overhead graphs that we did today.

Since I did not have protractors for you to purchase in class ( I will soon, 50 cents per protractor - amazing bargain :)  ), you do not have to hand in the homework problem (vectors 1 question 4 in the packet) for tomorrow. Just try to do it; if you do not have access to a protractor, you may estimate the angle.

Here is a link to some videos and animations showing the graphical method of adding vectors:
http://www.youtube.com/watch?v=pimr9I92GZY
http://video.google.com/videoplay?docid=-5528554074758763042#docid=736209380734386925

http://video.google.com/videoplay?docid=-5528554074758763042#

http://faraday.physics.utoronto.ca/PVB/Harrison/Flash/Vectors/Add2Vectors.html

http://faraday.physics.utoronto.ca/PVB/Harrison/Flash/Vectors/Add3Vectors.html

http://www.walter-fendt.de/ph14e/resultant.htm

AP Chem assignment/ equation-writing worksheet is now posted on Blackboard. Complete the worksheet and hand it in, in class, on Monday.
Email me, if you have questions.

Physics - we completed the Relationship between Weight and Mass Lab by seeing how to properly graph and draw a best-fit line among data points. We discussed how to obtain the slope of that line, as well as the meaning of the slope and its relation to the direct proportion equation W=km ( y = kx) .
On Monday, we will discuss vector and scalar physical quantities.
Have a great break already.

AP Chem- congratulations on completing your first in-class test. The vast majority of you clearly worked hard, were focused, and wrote detailed answers. Thank you.
The better you perform, the faster I'll be able to get the tests back to you. We must hit the ground running on Monday, when we'll finish expanding upon some of the topics from the summer assignment.
By Thursday night, I'll post a worksheet for you to do over the break.

Physics- We discussed the common natural relationships found between variables: the direct proportion, the inverse proportion, and the square/exponential proportion. We wrote the mathematical formulas that solve for each of these relationships, and we also sketched the lines or curves that show these relationships - these lines or curves can be plotted from their respective equation.

We discussed the difference between mass (the amount of matter that makes up/comprises an object) and weight (the gravitational force of a given planet pulling on that mass). So, though you would be the exact same person having the same MASS on Jupiter as you do on Earth, your WEIGHT is much greater on Jupiter because Jupiter is much more massive than Earth, and will therefore attract you via gravitation with a much greater force.

We did a spring-scale lab that shows the relationship between mass and weight (in NEWTONS, as determined by a calibrated spring) on Earth. We will graph the data together to make sure that we all conform to the same scientific graphing conventions.

I didn't collect it today, but please bring in your signed lab safety contract tomorrow. Thank you.

AP Chem - we discussed acid/base lab safety and writing net ionic equations.
Tomorrow's test will be given in the initial period and will last one hour. Plan to work through the bell. You must work for the entire time alotted - if you think that you are done early, go back and repeatedly check your work, and try to provide further detail in your answers. I will never collect a test early.
The test will reflect the summer assignment and also have a few questions on the lab safety that we discussed.
Note - this is an AP class so the QUALITY of your test-work HEAVILY affects your grade as it does on the AP exam. Tomorrow's test covers mostly basic first-year chemistry skills but you will not have the heavily detailed reference table for help. You must correctly spell the elements e.g. FLOURINE is unacceptable and will cause a point deduction. F is the symbol for FLUORINE as in "fluorine has the "flu" ".  Check that you spelled everything correctly on your practice test.
Detail is required for any answer that requires a description or an explanation. You can and should use accompanying drawings/diagrams to clearly get your point across.
Take the above advice to heart.

Physics - we discussed the demonstration that showed that, neglecting air resistance, different mass objects fall at the same rate, with the same acceleration, towards the Earth. We reasoned that the greater the mass of an object, the greater its force of gravitational attraction. However, the greater the mass of an object, the greater its INERTIA i.e. the more force required to move it! These opposing factors balance out to make all objects move towards the Earth with the same acceleration.

We completed a lab safety discussion and worksheet. Please have the safety contract signed over the weekend.

Welcome to our class blog, Physics and AP Chem students.

I was nice meeting you today, and I anticipate a great year ahead, filled with learning, growth, and some laughs too.

As you were told in class, this blog provides a daily synopsis of the notes and activities from class.


Physics- today, we went through the formalities of book and course requirement distribution.
Be sure to get the course requirement sheet signed by your parent or guardian and return it to me in class tomorrow.

AP Chem - today we went through the formalities of book and course requirement distribution. I collected the summer assignments. We will have a test on that material next Wednesday, September 8.