Energetics I
State three examples of exothermic reactions.
combustion, neutralisation and reaction between metal and acid
State three examples of endothermic reactions.
Decomposition, Dehydration, Photosynthesis
Four factors that affect the rate of a chemical reaction
Surface area, Temperature, Concentration, Catalyst
How does decreasing pressure affect the position of the equilibrium?
The position shifts in the exothermic direction.
Astronaut Tatsumaki, with a mass of 48 kg, is standing on the surface of a fictional celestial body, Planet X. The acceleration due to gravity on Planet X is approximately 12 N/kg. Calculate her weight on the surface of Planet X, considering the gravitational force exerted by the nearby gas giant, which contributes an additional acceleration due to gravity of 5N/kg in the same direction.
48 * 17 = 816 newtons
For an endothermic reaction, if the activation energy is 75 kJ/mol and the enthalpy change is +50 kJ/mol, calculate the energy of the reactants compared to the energy of the products.
-50 kJ/mol
In an exothermic reaction, if the activation energy is 80 kJ/mol and the enthalpy change is −120 kJ/mol, calculate the energy of the reactants compared to the energy of the products.
+120 kJ/mol
State the scientific name of marble chips.
calcium carbonate
What does ‘dynamic’ mean for dynamic equilibrium?
The reactions are still continuing.
What does Tatsumaki weigh on Earth?
480 newtons.
What chemical equation is used to calculate the enthalpy change for the decomposition of solid silicon dioxide into its elements?
SiO2(s) —> Si(s) + O2(g)
State the balanced chemical equation to find the enthalpy change for the combustion of 1 mole of octane (C8H18).
2C8H18 + 25O2 —> 16CO2 + 18H2O
The concentration of a reactant, 𝐴 , in a chemical reaction, is given by the function:
A(t) = 3t² - 4t + 5, where t is the time in seconds and the concentration 𝐴 is in moles per dm³. Calculate the instantaneous rate of change of the concentration of reactant A at t=3 seconds.
14 moles / dm3 s
State the equation that links the number of moles and volume (in millitres) of a gas at RTP.
Volume = moles x 24,000
Tatsumaki with a mass of 48kg is standing on the surface of the Moon, where the acceleration due to gravity is approximately 1.62 N/kg. If she jumps vertically with an initial velocity of 3 m/s upwards, how high will she reach before gravity pulls her back down?
2.78 m