Dimensional Analysis

In class, we took notes covering dimensional analysis. Dimensional analysis is used to convert one quantity to another. By using conversion factors, we can calculate out the equivalent in the desired unit. In order to determine the equivalent in the desired unit, the sought for unit must be used in the numerator. The equation for dimensional analysis is the following: given units x (desired units/given unit)= the solved desired unit.

I found these links helpful for dimensional analysis:
http://www.alysion.org/dimensional/fun.htm
https://www.sophia.org/tutorials/dimensional-analysis-unit-conversion

   

                   













https://www.sophia.org/tutorials/
dimensional-analysis-unit-conversion

http://www.math-salamanders.com/metric-to-standard-conversion-chart.html

Significant numbers

In class, we learned the difference between accuracy and precision, which is especially important in chemistry. Accuracy is the proximity of a measurement to the true value of a quantity; whereas, precision is the proximity of several measurements to each other. In other terms, accuracy depends on the technique and precision depends on how reproducible the measurement is. A measurement with accuracy usually also has a component of precision. In chemistry, significant figures are used to show the value of something being measured. Significant figures include zeros that are between whole numbers, zeros at the end of a number if there's a decimal point, all numbers in scientific notation, and all nonzero integers. With these significant figures, we can estimate one digit past the calibration of the instrument being used for the measurement. When adding or subtracting significant figures, the answer is rounded to the smallest number of decimal places present in the equation; on the other hand, multiplication and division are rounded out to the smallest number of significant digits in the equation.

I found some helpful links for determining significant figures and using them in problems:
http://chemistry.about.com/od/mathsciencefundamentals/a/sigfigures.htm
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch1/sigfigs.html
http://chemwiki.ucdavis.edu/Analytical_Chemistry/Quantifying_Nature/Significant_Digits

Classification of Matter

In order to properly identify matter, there are a series of questions you have to go through.

This flowchart is very helpful in properly identifying matter as heterogenous, a homogenous mixture, a compound or an element.

Matter can go through different changes which can be identified as a physical or chemical change. With a physical change, the identity of the substance is the same but the state the substance is in changes. In the case of a chemical change, however, the change results in a different substance than the original. We also learned three techniques for separating substances: filtration, distillation, and chromatography. Filtration is used for the separation of solid substances, distillation is used for substances with different boiling points, and chromatography is used for liquids with a difference in polarity.

I found these links helpful for classifying matter:
http://www.chemprofessor.com/matter.htm
http://chemwiki.ucdavis.edu/?title=Textbook_Maps/General_Chemistry_Textbook_Maps/Map:_Brown,_LeMay,_%26_Bursten_%22Chemistry:_The_Central_Science%22/01._Introduction:_Matter_and_Measurement/1.2:_Classification_of_Matter

Aspirin Lab

Yesterday we took the pre-lab quiz for our aspirin lab to see who got to participate in the lab. Out of those in the second group for the lab, only one set of partners passed the quiz. Everyone else just had a study hall an extra two days while the one set of partners conducted the lab. The pre-lab quiz contained a sentence directly from the lab packet, as well as, a question asking about the mass of the beginning substance and the drops of the liquid used in the lab. I didn't read the packet carefully enough to get the fill in the blanks for the sentences or to remember the mass of the additional things added to the original substance. For the next pre-lab quiz, I know I need to read the packet more carefully and more frequently in order to properly understand the information. 

Archaeology Lab

On Tuesday in class, my lab partner and I conducted an experiment to coincide with our current subject for notes, half-lives. During this lab, we had to cut out 567 squares out of paper given to us. These squares represented the number of atoms present. As we continued the experiment, we put all of the paper squares in a shoe box and shook them up. The squares that showed white were removed from the box and represented the decayed atoms. We did this another five times, going through six half-lives. After each half-life, we totaled up the number of decayed atoms and the number of radioactive atoms left to get our data for this experiment.