Chapter 16 Laboratory: Electrochemistry 305CUTIOA nS
Although none of the materials used in this lab session is
particularly hazardous, make sure to dispose of the food
items after use. DO NOT EAT ANY FOOD ITEM used in
this session. The food items will be contaminated with
metal ions, including toxic heavy-metal ions. Wear splash
goggles, gloves, and protective clothing.z
POCEDURER
1.ou have not already done so, put on your splash If y
goggles, gloves, and protective clothing.
- Use steel wool or sandpaper to polish each of the
electrodes to remove surface oxidation, oils, and other
contaminants. - Use the knife to make two slits in the one of the lemons,
spaced as far apart as possible, and large enough to accept
the electrodes. It’s important that the two electrodes do
not touch once they are inserted into the lemon. - Insert the copper electrode in one of the slits and the
magnesium electrode in the other slit. - Touch or clamp one of the leads from the DMM to each of
the two electrodes and observe the voltage reading on the
DMM. If necessary, reverse the leads to obtain a positive
voltage reading. Record the voltage reading to 0.01V on
line A of Table 16-7. - Switch the DMM to resistance mode and record the
resistance reading on line A of Table 16-7. - Switch the DMM to current mode and record the current
reading on line A of Table 16-7. - Repeat steps 3 and 4 to prepare the other two lemons.
- Use a patch cable to connect the copper electrode
on the first lemon to the magnesium electrode on the
second lemon.
Use patch cables to connect the magnesium electrode
on the first lemon to one of the DMM terminals and the
copper electrode on the second lemon to the other DMM
terminal. If necessary, reverse the cable connections on
the DMM to obtain a positive voltage reading. Record that
voltage reading on line B of Table 16-7.
Switch the DMM to resistance mode and record the
resistance reading on line B of Table 16-7.
Switch the DMM to current mode and record the current
reading on line B of Table 16-7.
Add the third lemon to the circuit by disconnecting the
copper electrode on the second lemon from the DMM and
reconnecting it to the magnesium electrode on the third
lemon. Then connect the copper electrode on the third
lemon to the DMM terminal. Record the voltage reading
on line C of Table 16-7.
Switch the DMM to resistance mode and record the
resistance reading on line C of Table 16-7.
Switch the DMM to current mode and record the current
reading on line C of Table 16-7.
Disconnect all of the patch cables.
Use a patch cable to connect the copper electrode of the
first lemon to the copper electrode of the second lemon.
Use a second patch cable to connect the magnesium
electrode of the first lemon to the magnesium electrode
of the second lemon.
Use patch cables to connect the magnesium electrode
on the first lemon to one of the DMM terminals and the
copper electrode on the first lemon to the other DMM
terminal. If necessary, reverse the cable connections on
the DMM to obtain a positive voltage reading. Record that
voltage reading on line D of Table 16-7.
Switch the DMM to resistance mode and record the
resistance reading on line D of Table 16-7.
Switch the DMM to current mode and record the current
reading on line D of Table 16-7.
Use a patch cable to connect the copper electrode on the
third lemon to the copper electrode on the second lemon,
and a second patch cable to connect the magnesium
electrode on the third lemon to the magnesium electrode
on the second lemon. Record the voltage reading on line E
of Table 16-7.
Switch the DMM to resistance mode and record the
resistance reading on line E of Table 16-7.
Switch the DMM to current mode and record the current
reading on line E of Table 16-7.dISpoSAL: dispose of the lemons with household
waste. The electrodes can be retained for later use.FIGURE 16-5: A two-cell series lemon-powered battery