Oxygen and hydrogen will not react until a lighted splint is used. This is because [blank_start]energy[blank_end] must be supplied to the reaction to start it.
Answer
energy
Question 2
Question
Two solutions are added together. The temperature goes down. What type of reaction is this?
Answer
exothermic
endothermic
Question 3
Question
The temperature of 50 ml acid, in a 100 ml beaker was 18 Celsius. 2 g of calcium carbonate was added, and when it finished reacting the temperature was now 42 Celsius. The temperature change was [blank_start]24[blank_end] Celsius.
Answer
24
Question 4
Question
Using the given bond energies, calculate the overall energy change of this reaction. (remember that bond breaking is a positive energy process [requires energy], and bond making is a negative energy process [releases energy]).
Overall energy change is [blank_start]-183[blank_end] kJ/mol
Bonding breaking is an [blank_start]endothermic[blank_end] process, whilst bond making is an [blank_start]exothermic[blank_end] process. In an exothermic reaction, the energy release from forming bonds is [blank_start]greater[blank_end] than the energy used to break them.
Answer
endothermic
exothermic
greater
smaller
Question 6
Question
Which shows the correct reaction profile for an endothermic reaction?
Which of the following is not an example of an endothermic reaction?
Answer
electrolysis
combustion
photosynthesis
thermal decomposition
Question 8
Question
If the energy change of a reaction has a positive (+) value, then the energy change is [blank_start]endothermic[blank_end]; if is has a negative (-) value, then the change is [blank_start]exothermic[blank_end]