The Joys of Simple Life

I was discussing classification of matter with my students. We were trying to classify substance whether as pure substance or mixture. If pure substance, if it is element or compound. If it is mixture, if it is homegeneous or heterogeneous. It was kind of easy for most, at least taking a break from dimensional analysis which some students were shocked they did not expect chemistry to deal with a lot of mathematical problem solving. they thought it is just like other sciences where they dont have to deal with numbers. so, they were glad when we stepped into classification of matter, at least, a rest from analytical solving problems with them.

when i asked about air, i did not specify exactly the air in this room, i just put air. some said it is homogeneous mixture, some said it is heterogeneous mixture. so i said, what about the air in this room? they look around, and one said, " we see nothing", hehehe. then one said it is heterogenous because the smoke coming out from the car’s exhaust are so visible that put layers in the air. that’s a very good observation, but no one has answered yet the air in our classroom. i told them to focus in a sample of air inside our room, still some would insist they see nothing. so, i asked them if you dont see anything, would that mean there is no air around you? of course, they said there should be air, otherwise, we all die from lack of oxygen. finally, they were able to unite into saying the air in our room is homogeneous since they see nothing meaning they could not distinguish the layers of different gases in the air. then, i told them to now look out, they opened the blinds to see the outside. i asked them, "how do you classify the air outside this room?" they said, homogeneous, no fogs can be seen. then, one of the student asked, what about early morning, when we walk in the clouds since oftentimes our morning is very foggy due to the marine layer with very poor visibility, the surrounding only clears when the sun starts to warm the earth and the fog dissipates. so i asked them, "what do you think is the reason for poor visibility? what blocks your vision?" they said, "the particles of water, tiny droplets of water suspended in air". so, everybody agreed with the fogs and the clouds air is heterogenous since they see layers, layers of clouds.

then, i tried to summarize everything, "the air in this room is homogeneous since we see nothing meaning we dont see any definite layers, the air outside is homogeneous if there are no clouds or fogs, generally it is homogeneous by 9:00 am or 10:00 am when the sun breaks out from the clouds and the fog disappears. but if you look up in the atmosphere, air in the vast atmosphere is heteregeneous since there are clouds always seen, the clouds tell us the suspension of tiny droplets of water, a layer separating from other gases. after taking a shower, the air in the bathroom is heterogenous too since tiny droplets of water suspended in the air makes the bathroom foggy. but generally a given sample of air is homogeneous, and on on a clear day outside, air surrounding us is a homogeneous solution of gases."

then one said, "not in LA, surrounding air is always heterogeneous there. it is not because of the fog, they dont get as foggy as we do here in the morning, but they are always full of smog, and unlike fog which disappears with the sun out, smog even thickens when the sun is all out since all the cars are out too, so air is really heterogeneous there!"

this is the first time we had a long discussion about the classification of air, since generally before, when i asked about air, students will just generally unite into saying, "homogenous mixture", not taking into consideration the diffrent places, different conditions, but just a particular sample of air, which usually i would agree because i too am usually referring to just a particular sample of air around me at the moment we talk of air, that is air in the classroom.

too bad we didnt have enough time to challenge students how we can help our county maintain the homogeneity of the surrounding air. since i dont know if southern californians would be willing enough to give up driving their cars and take the bus and the railways instead. in LA, people always say that it is impossible to be around LA without a car, i beg to disagree. i had been to almost all city there by bus when i was very new in US before and was looking for a job who can sponsor me. LA  has good public transportation system only that people there often thinks that the buses are only for the poor people who can not afford a car. i know some who would want their family to drop them off and pick them up even if they can take the bus but they wont since they think it is too low class to take the bus. but you look at the roads of LA, it is crazy, even the freeways has 6 lanes in each opposite direction, but still not enough to take all the commuters there, my husband and i know always we are in LA everytime we travel from san diego to LA. in san diego, we travel maybe 70+ to 80+ miles per hour ( i know, this is way above the speed limit which is 65, but we dont understand the cars here drive like crazy, if we drive 65, we may be traffic obstruction, that is slowing down the traffic), then if we start to stall and sometimes to a full stop on a FREEWAY, we would joke, "welcome to LA dear". just too many cars out there, and if you take the bus, there are a lot of buses in LA and train systems, but only very few people take them. and yet, people complain about the smog each time! how can you help solve the problem if you can not take the solution? people eventually should warm up to the idea of public commute, like in NYC and SF to better the traffic flow and air quality.