|
|
 |
|
|
| TGC5:
Gases |
|
 |
LINKS |
 |
|
|
|
|
The videos of test with a lighted splint are simply to illustrate
difference in properties at this stage. The reactions are
explained in Changing substances: Advanced Topics.
Using these ideas (1): ‘Think for Yourself’
questions
This would be a good opportunity to ask students to hold up
voting cards for each answer and then follow up with explanations
by individual students.
‘Which of A and B shows the sample above the
boiling point of the substance?’
This shows particles in the gas state
so it must be above the boiling point.
‘Are the particles in A more energetic than
the particles in B? Explain.’
Yes. A is at a higher temperature
than B, so particles in A are more energetic than those in
B. (Heating the sample to a higher temperature has given the
particles more energy).
‘We can not usually see substances in the gas
state. Are the individual particles in A different from those
in B?’
No. In the gas state the particles
are far apart and too small to be seen on their own. When
there is a change from the liquid state to the gas state,
the particles are the same particles, but with more energy.
This is why it is still the same substance. (Note: Students
may already know of chlorine and nitrogen dioxide, which are
obviously not invisible: the key point is that you cannot
see any ‘bits’, lumps’ or ‘blobs’
because there are no big clumps containing many particles).
‘Is the ability of particles to hold onto each other
weaker in A than in B?’
No. The particles have not changed
so they have the same ability to hold onto each other. The
particles in A can move away from each other because they
are more energetic.
|
|
|
|
|
| a
Science Enhancement Programme CD-ROM 2005 |
|
user
guide |
| |
|
|
|
|
