Discussion Topic
Chemical energy sources are often portable
and provide large amounts of energy. Fossil
fuels are one kind of chemical energy source.
Most of the energy we use in the United
States is generated by the combustion of
fossil fuels. However, fossil fuel combustion
adds greenhouse gases to the atmosphere,
mostly CO2. One measure of the total
amount of greenhouse gases that are
emitted into the atmosphere each year is
called a carbon footprint. Read this article to
compare the carbon footprint of an average
person in the United States to an average
person around the world.
Knowing that greenhouse gases are
contributing to climate change, how can we
reduce our carbon footprint, particularly in
the United States? Could hydrogen fuel
replace fossil fuels in the future? Why or why
not? Should the size of a person's carbon
footprint be limited by law? Why or why not?

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray