COLLEGE CHEMISTRY 35 POINTS
Determine the percent yield when 12 g of CO2 are formed experimentally from the reaction of 0.5 moles of C8H18 reacting with excess oxygen according to the following balanced equation:

2 C8H18(l) + 25 O2(g)  16 CO2(g) + 18 H2O(l)

Please show your work.

6.81% is the percent yield when 12 g of CO2 are formed experimentally from the reaction of 0.5 moles of C8H18 reacting with excess oxygen.

Explanation:

Data given:

mass of carbon dioxide formed = 12 grams (actual yield)

atomic mass of CO2 = 44.01 grams/mole

moles of = 0.5

Balanced chemical reaction:

2 + 25 ⇒ 16 C + 18

number of moles of carbon dioxide given is

number of moles =

number of moles=

number of moles of carbon dioxide gas = 0.27 moles

from the reaction 2 moles of reacts to produce 16 moles of C

So, when 0.5 moles reacted it produces x moles

=

x = 4

4 moles of carbon dioxide formed, mass from it will give theoretical yield.

mass  = number of moles x molar mass

mass = 4 x 44.01

        = 176.04 grams

percent yield = x 100

percent yield = x 100

     percent yield  = 6.81 %

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.