In This Issue:
The Caliper V14 #1 Cover
Chemistry
Biology
Physics
CBL™ News
Workshops & Contests
Bits & Bytes
Science Humor

New Products:
New Motion Detector
Lower Priced Sensors
Exercise Heart Rate Monitor
Instrumentation Amplifier
Ion Selective Electrodes
Rechargeable Battery Pack
Logger Pro Books
CBR™
TI-86

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Are you ready for the Mole Day celebrations taking place across America during the early morning hours of October 23rd? Vernier Software is! Set those alarms for 6:02 a.m. and help us celebrate the First Annual Vernier Software Mole Day Contest. How do you enter? Easy! Just have your class (minimum 1 teacher and 5 students) make the first phone call to Vernier Software at precisely 6:02 a.m. in your time zone (Eastern, Central, Mountain, and Pacific only time zones east of Eastern Time use Eastern, west of Pacific Time use Pacific). We realize this imposes a hardship on some dedicated Vernier employees (6:02 a.m. Eastern is 3:02 a.m. Pacific time!). We will have our clock set according to the National Institute of Standards and Technology in Boulder, CO. Their URL is www.bldrdoc.gov/timefreq/javaclck.htm, or telephone (303) 499-7111. The winning class in each time zone will receive a class set of student versions of Graphical Analysis, Macintosh or Windows (limit 30 per class), and a Vernier Software -shirt for the teacher. But remember, no fair calling us early. After all, would you accept 6.01 x 10(exp)23 for Avogadro's Number?

Here is a great new idea from Irwin Talesnick (Queen's University, Kingston, Ontario) for demonstrating vapor pressure or pressure-temperature relationships in chemistry. We occasionally hear of the frustrations of students and teachers when some part of the rubber stopper apparatus loses pressure due to a poor seal during vapor pressure or pressure-temperature experiments in Chemistry with Computers or Chemistry with CBL. But no longer! Irwin recommends using the apparatus shown here (for vapor pressure). It uses a #5 Twist-it stopper (with two air-tight tapered valve connectors inserted into it) to ensure a perfect seal. One of the tapered valves has a 2-way valve that allows you to attach your 20-mL syringe with 2 to 3 mL of the liquid to be vaporized.

Once the system is closed and you have begun monitoring pressure, simply open the 2-way valve, squirt the liquid into the 125-mL Erlenmeyer flask and close the valve. Vapor pressure data (like that shown in the Logger Pro Screenshot) can easily be collected using any of our interfaces and data collection programs. Gently swirl the flask. Once the system equilibrates, the flask can be placed in water baths of varying temperature to investigate the relationship between vapor pressure and temperature.
The good news is that we now carry the additional valves shown in this figure in a Vapor Pressure-PT Kit. The assembled kit includes the rubber stopper, two tapered valve connectors, and one Luer-lock connector to the rubber tubing. Note that the syringe, rubber tubing, and one of the Luer-lock connectors are currently shipped with each Pressure Sensor. If the 2-way valve is closed, as shown here, the rubber stopper assembly can also be used in pressure-temperature experiments.

The order information is:
Vapor Pressure-PT Kit VP-ACC $5.00

Andrea Cobb (Chantilly HS, Chantilly, VA) has added a new touch to Experiment 14 in Chemistry with Computers and Chemistry with CBL (Conductivity of Saltwater). Instead of simply adding 1.0 M NaCl one drop at a time to distilled water and monitoring the increase in conductivity, she has students repeat the procedure using 1.0 M CaCl2 and 1.0 M AlCl3. This way students not only discover the relationship between conductivity and concentration, but also see the increase in conductivity as they go from NaCl to CaCl2 to AlCl3. The ratio of the slopes shown here corresponds to nearly the dissociated-ion ratio of 2 to 3 to 4 for the three compounds.