8.1 In Reaction 1, platinum (Pt) acts as a catalyst - NSC Physical Sciences - Question 8 - 2016 - Paper 2
Question 8
8.1 In Reaction 1, platinum (Pt) acts as a catalyst.
What NAME is given to the energy that a catalyst changes in a chemical reaction?
8.2 Reaction 2 reaches equilib... show full transcript
Worked Solution & Example Answer:8.1 In Reaction 1, platinum (Pt) acts as a catalyst - NSC Physical Sciences - Question 8 - 2016 - Paper 2
Step 1
What NAME is given to the energy that a catalyst changes in a chemical reaction?
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Answer
The energy that a catalyst changes in a chemical reaction is called activation energy.
Step 2
Is the reaction EXOTHERMIC or ENDOTHERMIC? Give a reason.
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Answer
The reaction is endothermic because the change in enthalpy (ΔH) is negative, indicating that energy is absorbed during the reaction.
Step 3
Write down TWO changes that must be made to increase the YIELD of NO2.
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Answer
Increase the pressure in the reaction vessel. This shifts the equilibrium towards the side with fewer moles of gas, thus favoring the production of NO2.
Add more NO or O2 to the reaction mixture. Increasing the concentration of reactants will drive the reaction forward, enhancing yield.
Step 4
What is the value of ΔH per mole of NO2 formed?
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Answer
The value of ΔH per mole of NO2 formed is -74.55 kJ.
Step 5
Write down the NAME of the type of reaction between an acid and a base.
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Answer
The reaction between an acid and a base is called neutralization.
Step 6
Which particle (PROTON or ELECTRON) is transferred during the reaction mentioned in QUESTION 8.3.1?
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Answer
During the reaction, a proton is transferred from the acid (NH4NO3) to the base (NaOH).
Step 7
Calculate the percentage purity of the ammonium nitrate sample.
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Answer
To calculate the percentage purity of the ammonium nitrate sample:
Calculate the moles of NH4NO3 based on the reaction:
n(NaOH)=2.4imes10−3mol
Since the mole ratio of NH4NO3 to NaOH is 1:1, the moles of NH4NO3 is also 2.4 × 10⁻³ mol.
Calculate the mass of pure NH4NO3 produced:
m(NH4NO3)=n(NH4NO3)×M(NH4NO3)
Where the molar mass of NH4NO3 is approximately 80 g/mol,
m(NH4NO3)=2.4×10−3mol×80molg=0.192g
Calculate the percentage purity:
Percentage Purity=(0.204g0.192g)×100≈94.12%
