Submit your questions for Ben in the
comments section for a Q and A session next week.
Heating zinc oxide with a blow torch
causes it to turn from a white powder into a golden yellow. The process reverses when the substance cools
back down to room temperature. The heat
drives out some oxygen from the ZnO lattice, cause some locations to have a Zinc
metal ion. This disruption in the
lattice is able to absorb more blue and violet
light, causing the overall
substance to look yellow.
here's a neat little
demo I've got some
zinc oxide powder in this metal dish
here take a look what happens when I
heat it up with a blowtorch as you can
see it turns a nice yellow color and you
might think well just because it's being
burned but take a look when it cools
back down the white color returns it's
actually a reversible process
the reason this occurs is because the
heat drives out some of the oxygen so
instead of zinc oxide some of the
locations inside that crystal lattice
become just zinc ion so the oxygen
pulled out of it and this change affects
how the substance is able to absorb
light this is the same reason that
metals like copper are sort of reddish
colored they're able to absorb shorter
wavelengths of light blue and purple
colors and the other colors are
reflected so you're left with sort of a
yellowish or an orange color when the
substance cools back down the oxygen in
the air is able to go back into the
lattice and convert it back to the
original zinc oxide form so I'm a little
late in thanking you guys for pushing
the channel over the hundred thousand
subscriber mark and to make it up to you
I'm going to do a question and answer
session next time so please post your
questions in the comment section of this
video and I will answer as many as I can
next week okay see you next time
bye
s
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