I\'m confused with my pre lab can I get some help 2 The reaction of 1 142 grams

Question

I'm confused with my pre lab can I get some help

2 The reaction of 1 142 grams of octane, one mole, with oxygen can be represented by: 9H20(g) 5074 kilojoules + + CsH,8 () 25/2o2(g)-8CO2(g) + Find the heat energy released when 1,00 gram of octane reacts with oxygen. This is the fuel value of octane Find the approximate mass of methanol (CH,OH) required in a typical heat of combustion experiment by completing the calculations below a) A 1 18.5g glass flask with specific heat capacity 0.857 Joules/g undergoes a 3. temperature change of 10.0 °C. How much heat energy is absorbed by the flask? b) 192.2g of water with specific heat capacity 418 joules/g also is heated and undergoes a temperature change of 10.0 C. How much heat energy is absorbed by the water? c) The total energy used to warm the water and glass flask is the same as the heat energy released by the combustion of the methanol fuel. What is this energy in units of joules? in units of kilojoules? d) Methanol produces 19.9 kilojoules of energy for each gram that undergoes combustion. Find the mass of methanol equired to produce the total heat energy calculated in part c)

Explanation / Answer

1) When one mole of octane(114.2g/mol) is burnt the energy released = 5074 kJ

Hence when 1 g of octane is burnt the energy liberated = 1g x 5074 kJ /114.2g

= 44.43 kJ

Thus the fuel value of octane = 44.43 kJ/g

2) a)

Mass of flask = 118.5g

heat capacity of flask = 0.857J/g.C

temperature difference = 10 C

The heat absorbed by the flask = mass x specific heat x rise in temperature

= 118.5g x 0.857J/g.C x 10 C

=1015.545 J

b) mass of water = 192.2g

specific heat of water = 4.18J/g.C

diefference in temperature = 10C

Thus heat change invlved = mass x specific heat of water x dfference in temperature

= 192.2g x 4.18J/g.C x 10C

= 8033.96 J

C) the amount of heat liberated by burning methanol = [amount of heat absorbed by water + g;lass flask]

= 8033.96 J + 1015.545 J

=9049.505 J

= 9.05 kJ

d) one gram of methanol produces 19.9 kJ of energy on combustion

mass of methanol that produces 9.05 kJ of heat

= 1gx 9.05kJ /19.9kJ

= 0.4547 g of methanol

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