Year 1 (Term 1) 2015 Joseph Rendall Graphing Methods 2 Year 1 (Term 1) 2015 Joseph Rendall

To the computer lab For a quicker method

Lab Notebook (Sections) Introduction Date, Statement of Purpose or Research Question, Source of Experiment Experimental Plan List of equipment and steps required to do the experiment. Safety requirements. Observations and Data Write down almost everything. Include your raw data tables. Discussion of Results (Data Evaluation) Thoughts on experiment, the results and possible future significances Conclusion Summarize the goal of your experiment and what was determined by the experiment

Lab Notebook (Sample Layout) Title Date Data Introduction 2-3 sentences Experimental plan Construct pendulum as shown Displace pendulum … Observations Lists and/or drawings http://www.penaddict.com/blog/2011/5/31/bookfactory-scientific-and-engineering-notebook-review.html

Lab Notebook (Sample Layout) Discussion of Results 2-6 sentences Conclusion 2-3 well constructed and succinct sentences http://www.penaddict.com/blog/2011/5/31/bookfactory-scientific-and-engineering-notebook-review.html

Hopes for the new process You’ll understand physics better, be able to design your own experiments and write quality questions.

Measurements and Uncertainty/Error All measurements include some uncertainty, it is the job of the scientist (or teacher-scientist) to identify the quantity of uncertainty in the measurement and identify what types (quality) of error there are in the experiment. Types of error or uncertainty Systematic Biases data in one direction Human We all make mistakes (transposing numbers, ect.) Random Doesn’t bias data in any direction When data is averaged the results will be accurate but not precise Instrument precision Sensitivity of instrument Activities

Year 1 Pratical Exams (Challenges and Tips for passing) Hardest part is knowing “what the question asking!?” Ask for all things to be clarified! Exam time management skills Some exams are packed with information Rewriting data tables and graphs can cause you to loose valuable time Don’t cross out bad work until you have replaced it with good work Be sure to attempt all parts of questions Hands-on skills Make sure during labs you get a chance to manipulate the apparatuses Be exacting but efficient in your handing of the apparatuses Units Know your units or how to determine them

Reports for Lab’s Include Title Introduction (Background of Physics Topic and Experiment) Methods (Description of Experiment, Sometimes Raw Data) Results (Tables and Explanation) Conclusion (Significance of Results) Discussion (Future Research) References

Handout Questions Thoughts Think Pair Share

Example Intro. The objective of this lab was to determine the energy involved in the phase changes of ice, water, dry ice (sold CO2), and liquid nitrogen. By placing two substances in contact with each other – by placing them in an insulated container – heat energy is transferred from the warmer substance to the cooler substance. The energy change of the first substance can be calculated from its mass m, temperature change (delta t), specific heat s, according to the equation q = ms(delta t). If the system is well insulated then the energy change of the second substance can be assumed to be equal, but opposite in time – thus all energy is conserved. 

Example Intro. A procedure utilizing this information was used to determine the energy involved in the phase changes of ice water, dry ice, and liquid nitrogen. The expected result for the experiment would be that CO2 requires the most energy since it is going from solid to a gas (sublimation). As for water and nitrogen, they would be around the same amount of energy since fusion and vaporization – only changing by one state in matter. This experiment is important because phase changes are prevalent in chemistry, and one should be aware of the energy associated with them. 

Example Methods Part 1 1) 25 ml of water was heated. 2) The weight was measured. 3)20 grams of ice was added. 4) Using the probe, the initial value was recorded. 5) The ice was added to the water. 6) When all the ice melted and the temperature started to increase, the T was recorded. Part 2 Similar to part one, but 40 g of liquid N2 was added. Part 3 Similar to parts one and two, but 15 g of dry ice(CO2) was added.

Example Data Mass and temp hot water: Mass and temp solvent: 50g at 70 C 20g at 0 C 46.51g at 53 C 39.85g at -196 C 51.37g at 63 C 15.04g at -78 C

Example Results

Example Results

Example Conclusion The energy involved in the phase change of liquid nitrogen to gas was 6.12kJ/mol, the energy change of solid CO2 to gas was 27.04kJ/mol, and the energy change associated with the change from ice to liquid was 572kJ/mol). These results were found by measuring the heat transferred from the first substance to the second substance, assuming minimal energy loss to the surroundings. In this lab, the concepts of conservation of energy and specific heat were utilized in order to calculate phase changes, and enhance one’s understanding of how energy is associated to changes in matter.

Example Discussion The results give the change in heat of a substance by knowing the specific heat of water and the starting temperatures of the two solutions. This can be done for most mixable substances where the boiling temp and freezing temp are known. These temperatures and masses lead to knowing the change in energy of the mixing. There could be a large source of error in the water ice part of the lab because the amount of water was poured in was measured in a beaker, not weighed like the parts for dry ice and N2. The last 2 parts of the lab turned out with very low percentages of error. (mainly doing to the weighing of the hot water added)

Example References