Standard Enthalpy Change

According the given enthalpy diagram. Which letter shows the enthalpy of the reaction?

• B

• C

• D

• E

An energy profile for a reversible chemical reaction is shown. According to this profile, the activation energy of the reverse reaction is equal to . . . . .

• D

• A - B

• C - B

• C - D

Given to you the reaction of sodium thiosulphate with the water below.
Na₂S₂O₃(s) + 5H₂O(l) --> Na₂S₂O₃.5H₂O(s) .
This reaction is an example of . . . . .

• combustion

• Neutralization

• Atomisation

• Hydrated from anhydrous salt

Here is the reaction between sulfur with oxygen.
S + O₂ --> SO₂
According to the standard enthalpy change we could classify as standard enthalpy of ........... and .........

• combustion and formation

• Formation and atomisation

• neutralization and combustion

• atomization and neutralisation

The activation energy is the ​ (a)   energy required for a reaction to occur. This means that the reactant molecules have enough kinetic energy to ​ (b)   successfully and overcome the repulsion caused by outer electrons. If the activation energy is high for a reaction, then only a ​ (c)   particles will have enough energy to collide so the reaction will be ​ (d)   . If a reaction has a low activation energy then the reaction will be ​ (e)   as a lot of particles will have the required energy.

• minimum
• average
• collide
• few
• slow
• fast

Give to you the formula to calculate the energy that is released/absorbed during the chemical reaction.
 Q= m c ∆T
what represents each symbol

• specific heat

• c

• changing temperature

• ∆T

• mass

• Q

• energy

• m