The world burns appro
year. use the con
tion a
can
burns approximately 3.7 x 10 kg of fossil fuel per
ise the combustion of octane as the representative reac-
and determine the mass of carbon dioxide (the most signifi-
greenhouse gas) formed per year. the current concentration
of carbon dioxide in the atmosphere is approximately 399 ppm
(by volume). by what percentage does the concentration in-
crease each year due to fossil fuel combustion? approximate the
average properties of the entire atmosphere by assuming that
the atmosphere extends from sea level to 15 km and that it has
an average pressure of 381 torr and average temperature of 275 k.
assume earth is a perfect sphere with a radius of 6371 km.

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol

no, the red giant is the hottest with 2.00.000.000 degrees celsius. while the white dwarf only 25,000 degrees celsius.

the answer would be a