Heat of reaction equations Using simultaneous equations.

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Presentation transcript:

Heat of reaction equations Using simultaneous equations

Simultaneous equations GIVEN:ΔH A + B = C-50 D + E = F+24 F + C = H???

Simultaneous equations GIVEN:ΔH A + B = C-50 D + E = F+24 F + C = A+ B + C + D???

Simultaneous equations GIVEN:ΔH A + B = C-50 D + E = F+24 A+ B + E + D= H -26

INTERPRETING DATA In any reaction, the heat taken in or given out is determined by the direction of the reaction. Always work left to right ΔH A + B = C - 50

INTERPRETING DATA In any reaction, the heat taken in or given out is determined by the direction of the reaction. Always work left to right ΔH A + B = C - 50 C = A + B......

INTERPRETING DATA In any reaction, the heat taken in or given out is determined by the direction of the reaction. Always work left to right ΔH A + B = C - 50 C = A + B +50

INTERPRETING DATA In any reaction, the heat taken in or given out is determined by the direction of the reaction. Always work left to right ΔH A + B = C - 50 C = A + B +50 If the direction of the reaction is reversed, the sign of the energy is changed (- to + or + to –)

Using this to solve an unknown reaction 2009 Q6(e) The combustion of Butene C 4 H 8 is described by the following balanced equation. C 4 H 8 + 6O 2  4CO 2 + 4H 2 O ΔH = –2710 kJ mol –1 The standard heats of formation of water and carbon dioxide are –286 and –394 kJ mol –1, respectively. Calculate the heat of formation of C 4 H 8

What have we been told?? 2009 Q6(e) The combustion of Butene C 4 H 8 is described by the following balanced equation. C 4 H 8 + 6O 2  4CO 2 + 4H 2 O ΔH = –2710 kJ mol –1 This is the energy given out when butene is burned in oxygen

What have we been told?? 2009 Q6(e) The combustion of one of Butene C 4 H 8 is described by the following balanced equation. C 4 H 8 + 6O 2  4CO 2 + 4H 2 O ΔH = –2710 kJ mol –1 The standard heats of formation of water and carbon dioxide are –286 and –394 kJ mol –1, respectively. Calculate the heat of formation of C 4 H 8

What have we been told?? The standard heats of formation of water and carbon dioxide are –286 and –394 kJ mol –1, respectively. ΔH = kJ mol –1 H 2 + ½O 2  H 2 O -286 C + O 2  CO

What do we need to know? 4C + 4H 2  C 4 H 8 ΔH = ??? Using all the given info one has to manipulate the given formulas to leave the needed one. The question seeks to answer if the formation of butene is exothermic or endothermic

What’s next? Write down all the info you have. ΔH = kJ mol –1 H 2 + ½O 2  H 2 O -286 C + O 2  CO C 4 H 8 + 6O 2  4CO 2 + 4H 2 O –2710

What’s next? Write down all the info you have. ΔH = kJ mol –1 H 2 + ½O 2  H 2 O -286 C + O 2  CO C 4 H 8 + 6O 2  4CO 2 + 4H 2 O –2710 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? ΔH = kJ mol –1 H 2 + ½O 2  H 2 O -286 C + O 2  CO C 4 H 8 + 6O 2  4CO 2 + 4H 2 O –2710 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? ΔH = kJ mol –1 H 2 + ½O 2  H 2 O -286 C + O 2  CO C 4 H 8 + 6O 2  4CO 2 + 4H 2 O –2710 4CO 2 + 4H 2 O  C 4 H 8 + 6O C + 4H 2  C 4 H 8 ΔH = ??? reverse

What’s next? ΔH = kJ mol –1 H 2 + ½O 2  H 2 O -286 C + O 2  CO C 4 H 8 + 6O 2  4CO 2 + 4H 2 O –2710 4CO 2 + 4H 2 O  C 4 H 8 + 6O C + 4O 2  4CO C + 4H 2  C 4 H 8 ΔH = ??? x4

What’s next? ΔH = kJ mol –1 H 2 + ½O 2  H 2 O -286 C + O 2  CO C 4 H 8 + 6O 2  4CO 2 + 4H 2 O –2710 4CO 2 + 4H 2 O  C 4 H 8 + 6O C + 4O 2  4CO H 2 + 2O 2  4H 2 O C + 4H 2  C 4 H 8 ΔH = ??? x4

What’s next? ΔH = kJ mol –1 4CO 2 + 4H 2 O  C 4 H 8 + 6O C + 4O 2  4CO H 2 + 2O 2  4H 2 O C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???

What’s next? 4C + 4H 2  C 4 H 8 ΔH = ???