Topic 1: Stoichiometric Relationships

Question 1

If the fuel blend was vaporized before combustion, predict whether the amount of energy released would be greater, less or the same. Explain your answer.

Answer 1

Greater. Gaseous fuel has greater enthalpy than liquid fuel because it had to absorb greater enthalpy to get to that state, thus it will release a greater amount of energy too.

Question 1

Explain why the relative atomic mass of cobalt is greater than the relative atomic mass of nickel, even though the atomic number of nickel is greater than the atomic number of cobalt.

Answer 1

Cobalt has a greater proportion of heavier isotopes / cobalt has greater number of neutrons.

Question 2

Suggest one reason why the values of rates of reactions obtained at higher temperatures may be less accurate.

Answer 2

At higher temperatures, the reaction is faster, so it becomes harder to measure the exact time the mark disappears, increasing experimental error.