Ch.7.1 Flashcards
the layer of air on Earth is called the ___________________.
atmosphere
the atmosphere is ___________________ to living things. without air, living things _____________ ______________.
essential, cannot survive`
what is air made of?
air is a mixture of gases.
what does air consist of? what is the percentage of these gases in air?
nitrogen (78%), oxygen (21%), carbon dioxide (0.03%), noble gases (0.9%), water vapour and small amounts of other gases (0.07%).
Noble gases are mainly ___________________. Other examples include ______________ and ______________.
argon, neon, helium
The ‘other gases’ in air includes:
methane, ozone, sulphur dioxide and nitrogen oxides etc
properties we study when we test for a certain gas: - - - - -
what colour is it? does it have a smell? does it burn? can it support burning? does it react with other chemicals?
-
it relights a glowing splint
it causes a burning splint to burn more brightly
-
it turns hydrogencarbonate indicator from red to yellow
it turns limewater from colourless to milky
how to test for gases with other chemicals:
—
add a few drops of that chemical to a test tube containing a gas.
how to test for water and water vapour?
-
both turn dr cobalt chloride paper from blue to pink.
how to test for nitrogen and noble gases?
-
there are no simple tests.
it is used to keep the cobalt chloride papers dry.
why is dry cobalt chloride paper used to test for water?
-
it is because a dry cobalt chloride paper shows a colour change when it is in contact with H2O.
why are there no simple tests for nitrogen and noble gases?
it is because these gases are very unreactive.
how is oxygen used in daily life?
—used to ______________ ______________ with ______________ ______________
—used to ___________ ______________ in a ______________ with a __________ ____________ in ______________, as such _____________________________________________________________________________________.
help patients, breathing difficulties
cut metals, mixture, gas fuel, industry, mixture burns to produce a very high temperature which is high enough for cutting metals
how is carbon dioxide used in our daily life?
—used in ________________________________________________________ as it _______________________________ and is _______________________________.
—used on ______________ to __________________________________________________, as ______________ carbon dioxide (___________________) ________________________________________________________.
used in fire extinguishers to put out fires, does not support burning, denser than air
stages, produce a fog effect, solid, dry ice, changes directly to a gas at room temperature.
Both oxygen and carbon dioxide are involved in _____________________________________ of living things: including ______________________________________________.
three essential life processes; photosynthesis, respiration, gas exchange
how is nitrogen used in our daily lives?
—used to __________________________________________ as it ______________________________________________________.
—______________ nitrogen with a ___________________________________________ is used for ________________________________________________________.
fill some food packages, helps prevent the food from going bad
liquid, temperature below -196°C, storing living cells and tissues
how is argon used in our daily life?
—used to ________________________________________.
fill light bulbs
how is helium used in our daily life?
—used to __________________________________________.
fill balloons and airships
how is neon used in our daily life?
—used to ________________________________.
fill advertising lights
