Slides in this set
Oxygen in the air
· The percentage of oxygen in the air can be
measured by passing a known volume of air
over hot copper, and measuring the decrease
in volume as the oxygen reacts with it. Here
are the equations for this reaction:
· copper + oxygen copper oxide
· 2Cu + O2 2CuO
· Gas syringes are used to measure the volume
of gas in the experiment.…read more
Evolution of the atmosphere
Its early atmosphere was probably formed from the gases given out by volcanoes.
The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. There
were smaller proportions of water vapour, ammonia and methane.
As the Earth cooled down, most of the water vapour condensed and formed the oceans.
It is thought that the atmospheres of Mars and Venus today, which contain mostly carbon
dioxide, are similar to the early atmosphere of the Earth.
Changes in the atmosphere
· So how did the proportion of carbon dioxide in the atmosphere go down, and the
proportion of oxygen go up?
· The proportion of oxygen went up because of photosynthesis by plants.
· The proportion of carbon dioxide went down because:
· it was locked up in sedimentary rocks such as limestone, and in fossil fuels
· it was absorbed by plants for photosynthesis
· it dissolved in the oceans.
· The burning of fossil fuels is adding…read more
How is the atmosphere of today
· Burning fossil fuels which releases carbon dioxide.
· Deforestation- trees are being cut down so that there is space for
new houses to be built and new roads to be created because of the
rise in human population, the trees are burnt or cut and also
releases carbon dioxide.
· And livestock farming.
· Sulfur dioxide can be thrown up high into the atmosphere when
volcanoes erupt. Along with carbon dioxide.…read more