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When she nor the key to change for a chemical reaction you can include that
with the balance chemical equation to give you
a thermal chemical equation
so here's a balanced equation
and you have the key chains delta H
they're is a slight difference between delta H and delta E that's beyond this class so
normally when you see a thermal chemical equation you're gonna see a written with delta H
rather than with delta E
delta H means the change in and pulpy
and the Entel pi is almost the same thing as heat
the technical difference is
if you measure the heat that constant pressure
the heat is equal to the change in chemical be and for most chemical reactions in the lab we work that constant pressure so Keats and and pulpy are
used interchangeably for most chemistry applications
this delta H is a positive number and that's
matches a positive two and remember a positive delta H
means the system is absorbing eight so this reaction requires an input of heat if we had gotten
another reaction with a negative delta H that means Exe open MIC
we can also use this
in the conversion factor because
this delta H this number of kill a jewels of heat
is required for if you're looking at the iron is coefficient of two tells you it takes two moles of iron to react
and it requires this number of
kill a jewels of heat if you were looking at the aluminum its two moles if you're looking at any chemical
the mole in the coefficient is equal to the number of kill a jewels from the balance them a chemical equation
so for example
if we calculate delta H
for reaction that produces 585 g of aluminum
we turn that we're trying to figure out how many kill a jewels of heat
would be absorbed if the reaction produced 555 g of aluminum
we won a use our therma chemical equation as their conversion factor
and so we have to convert Grams of aluminum
in two moles of aluminum
using the periodic table
fine in the molar mass of 26.98
and then once we have moles of aluminum
we can turn it into kill a jewels of heat using the thermal chemical equation
the coefficient for aluminum as a two
and that requires an input of 852 kill a jewels
so multiplying gives us an answer of 8.76 times 10 to the third
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