The graph below shows a reaction profile for the reaction between methane and oxygen.
What does the label X represent?
Activation energy
Overall energy change
Reactants
Progress of the reaction
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The graph below shows a reaction profile for the reaction between methane and oxygen.
What does the label X represent?
Activation energy
Overall energy change
Reactants
Progress of the reaction
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Which is true about chemical energy changes?
Reaction type | Energy flows | Temperature of surroundings | |
A | exothermic | to the surroundings | increases |
B | exothermic | from the surroundings | decreases |
C | endothermic | to the surroundings | decreases |
D | endothermic | from the surroundings | increases |
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The reaction profile for making nitrogen monoxide, NO, is shown below:
What is the activation energy for this reaction?
+140 kJ
+180 kJ
+320 kJ
-330 kJ
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Chlorine reacts with methane in sunlight.
CH4 + Cl2 → CH3Cl + HCl
The diagram below shows the displayed formulae for the reaction of chlorine with methane.
The table below shows the bond energies and the overall energy change in the reaction.
C-H | Cl-Cl | C-Cl | H-Cl | Overall energy change | |
Energy in kJ/mol | 413 | 243 | X | 432 | -122 |
What is the value of X?
67 kJ
134 kJ
346 kJ
542 kJ
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How much energy is needed to break all the bonds in 0.025 g of nitrogen gas?
Relative atomic mass (Ar): N = 14
Bond | Bond energy in kJ/mol |
NN | 945 |
1701 J
1701 kJ
844 J
844 kJ
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What is the reading on the following thermometer?
28.3 oC
28.6 oC
29.2 oC
28.5 oC
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Endothermic reactions can be used in emergency sports injury treatment packs.
What is true about these packs?
Absorb energy from the surroundings and transfer it to the injury
Can be re-used
Usually contain ammonium nitrate and water in separate compartments
Cause the temperature of the surroundings to increase
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