Illustrated Guide to Home Chemistry Experiments

Chapter 14 Laboratory: Gas Chemistry 255

A IERd y C ExpLoSIoN

Dr. Paul Jones, one of our technical advisors, suggests an amusing use for any dry ice you

have left over when you finish this lab session. Place a chunk of dry ice in a disposable

latex glove and knot the top of the glove. As the dry ice warms, it sublimates from solid

to a gas and inflates the rubber glove. Eventually, the glove can stretch no farther, and it

explodes with a loud bang. Our dogs may never forgive me.

Just don’t use anything more robust than a thin latex glove. Confining dry ice in a glass

jar, plastic soda bottle, or a similar container can have tragic results. When the container

inevitably shatters, shards of glass or plastic moving at high velocity will puncture

anything or anyone in the area. People have been blinded and even killed by doing stupid

things with dry ice.

dISoALp S :

No waste products

are produced in this

laboratory session.

Save the alcohol for use

in your alcohol lamp

or similar noncritical

purposes.

7.emove the syringe from the dry ice bath and set it R

aside to return to room temperature. When it has done

so, verify that the volume has returned to the original

reading. (Press the plunger gently once or twice to

ensure that it can move freely; the readings should be

the same each time.)

8. Set the beaker aside with a watch glass or similar item
   loosely covering it. (Make sure that it is vented to allow
   gas to escape.) Allow the dry ice to be consumed and
   the alcohol to return to room temperature, which may
   require an hour or more. Once the alcohol is again at
   room temperature, you may return it to its container.
   The dry ice does not contaminate the alcohol any more
   than storing it in the freezer would. Allowing it to return
   to room temperature also allows dissolved carbon
   dioxide gas to dissipate.


9. Fill the second beaker with a mixture of tap water
   and ordinary ice, and allow the temperature to stabilize
   at 0°C. Make sure that some ice remains unmelted in the
   beaker.

TABLE 14-2: Observe the volume-temperature relationship of gases—observed and calculated data

Trial TemperatureActual volumeCalculated volume

A. Room temperature________.__ K____.____ mL n/a

B. Dry ice in alcohol ________.__ K____.____ mL ____.____ mL

C. Ice water ________.__ K____.____ mL ____.____ mL

D. Hot tap water ________.__ K____.____ mL ____.____ mL

E. Boiling water ________.__ K____.____ mL ____.____ mL

10.

11.

12.

13.

14.

Verify that the syringe is at the original volume—75% of full

scale, or whatever you used initially—and then immerse

the syringe in the ice-water bath, making sure that the

portion filled with gas is below the surface of the ice water.

Allow the syringe to remain in the ice-water bath for two

to three minutes to ensure that the gas has equilibrated

at the temperature of the bath, and then withdraw the

syringe and note the volume indicated. (Bump the

plunger.) Record the temperature of the bath and the

volume of the syringe on line C of Table 14-2.

Remove the syringe from the ice-water bath and set it

aside to return to room temperature. When it has done

so, verify that the volume has returned to the original

reading. (Bump the plunger.)

Repeat steps 9 through 12 using baths of hot tap water

and boiling water. Record the temperatures and volumes

on lines D and E of Table 14-2, respectively.

Calculate the expected volume at each temperature, and

enter the results on lines B through E in the right column

of Table 14-2.