Chemistry Honors – Class 24

Actually – We use a cashew…

Dates

• Periods A, C, D – Friday, February 28th

Recapping some things…

• You have been shown a way to record data and show calculations in your LNB. The goal is to practice how to easily communicate with other scientists. So, what did you do when allowed to write any way you wish to write in your LNB? Did you revert to a method other than what was taught? Sigh…
• Calorimeters prevent heat exchange with the outside world. So, (ideally) within the calorimeter one object is releasing heat and the other substance is gaining that exact same amount of heat. Since the quantities of heat are the same setting them equal to each other makes finding the “c” quite simple as long as you know the mass of both objects, the initial temperatures of each object (separately) and the final temperature of both together.
• Be sure that the specific heat capacity activity is in your LNB next week when I collect your next lab.

Today’s Lab Questions

• Why are we suing a cashew and not a peanut?
• What are you determining?
• Can this be measured directly?
• What is the role of the water?
• What measurements need to be made?
• What calculations should be performed to get a answer?
• How do you show calculations?
• What uncertainties are present? How do they impact your result?
• What is the “real” value? How close are your results?
• From label: 160 Calories per 28 grams of cashew
• Note that negative (-) numbers in science indicate direction and do not mean “less than zero” so if you calculate -350 joules of energy that means that 350 joules are LOST by the system

Homework

• Write up the lab in your LNB
• Be sure that all sections are properly finished in your LNB according to the formatting guidelines
• Remember: less is more