Illustrated Guide to Home Chemistry Experiments

250 DIY Science: Illustrated Guide to Home Chemistry Experiments

the incremental mass additions to some smaller value,

such as 250 g. If the first 500 g addition causes too little

volume reduction, as it may with a large-bore syringe,

increase the incremental mass additions to some larger

value, such as 1,000 g.

Repeat step 9, adding 500 g of lead shot each time

and recording each volume reading on the syringe in

Table 14-1. Continue adding mass until the container is

nearly full or the syringe fails to compress any more,

whichever comes first. As you add mass, keep an eye on

the stability of the apparatus, or you may find yourself

picking up 5 kilograms of lead shot from the floor, piece

by piece.

The atmospheric pressure, the mass of the empty

container and plunger, the bore area of the syringe, and

the masses added to the container are all known. Force

equals mass times acceleration (F = ma). Gravitational

acceleration (a) is 9.81 m · s–2. Pressure equals force

divided by area (P = F/A), where the area is the cross-

sectional area of the syringe. Using these data, calculate

the pressures and expected volumes for each of the

mass/volume readings, and record those values in the

right columns of Table 14-1.

7. Clamp the syringe as shown in Figure 14-2. Make sure
   that the cap of the syringe is pressing directly against
   the base of the ring stand. Otherwise, when you add
   mass to the container, the cap might pop off the syringe.


8. Obtain the atmospheric pressure using a barometer or
   from a local radio or TV broadcast. Convert that value to
   pascals and enter it on line D of Table 14-1.


9. Verify the initial volume reading on the syringe, and
   record that value as accurately as possible on line D of
   Table 14-1. (Your syringe may use cc graduations, which
   are the same as mL graduations for our purposes.)
   Weigh 500 g of lead shot and add it to the container above
   the syringe. If your balance does not have a 500 g capacity,
   do repeated weighings and accumulate the shot until you
   reach 500 g. Record the volume reading of the syringe
   on line E of Table 14-1. The first 500 g mass addition
   should cause a noticeable but not excessive reduction in
   volume. For example, with my setup, the first 500 g mass
   addition reduced the volume from 10.0 mL to 8.2 mL.
   Depending on the bore size and capacity of your syringe,
   you may need to modify the mass increments from 500 g
   to some other value. If 500 g causes too much volume
   reduction, as it may with a narrow-bore syringe, reduce

10.

11.

12.

TABLE 14-1: Observe the volume-pressure relationship of gases—observed and calculated data.

Item Observed valueCalculated pressureCalculated volume

A. Area of syringe bore _________ m^2 n/a n/a

B. Mass of empty container and plunger _____.____ g n/a n/a

C. Atmospheric pressure __________ Pa n/a n/a

D. Initial volume reading ____.____ mL n/a n/a

E. Volume reading (+500 g) ____.____ mL __________ Pa ____.____ mL

F. Volume reading (+1,000 g) ____.____ mL __________ Pa ____.____ mL

G. Volume reading (+1,500 g) ____.____ mL __________ Pa ____.____ mL

H. Volume reading (+2,000 g) ____.____ mL __________ Pa ____.____ mL

I. Volume reading (+2,500 g) ____.____ mL __________ Pa ____.____ mL

J. Volume reading (+3,000 g) ____.____ mL __________ Pa ____.____ mL

K. Volume reading (+3,500 g) ____.____ mL __________ Pa ____.____ mL

L. Volume reading (+4,000 g) ____.____ mL __________ Pa ____.____ mL

M. Volume reading (+4,500 g) ____.____ mL __________ Pa ____.____ mL

n. Volume reading (+5,000 g) ____.____ mL __________ Pa ____.____ mL