1. Methanol is made in large quantities as it is used in the production of polymers and in fuels.The enthalpy of combustion of methanol can be determined theoretically or experimentally.
(a) Using the information from Table 10 of the Data Booklet, determine the theoretical enthalpy of combustion of methanol.
(b) The enthalpy of combustion of methanol can also be determined experimentally in a school laboratory. A burner containing methanol was weighed and used to heat water in a test tube as illustrated below.
The following data were collected.
(i) Calculate the amount, in mol, of methanol burned.
(ii) Calculate the heat absorbed, in kJ, by the water.
(iii) Determine the enthalpy change, in kJ mol–1, for the combustion of 1 mole of methanol.
(c) The Data Booklet value for the enthalpy of combustion of methanol is –726 kJ mol–1. Suggest why this value differs from the values calculated in parts (a) and (b).
(i) Part (a)
(ii) Part (b)
2. (a) Explain why the relative atomic mass of argon is greater than the relative atomic mass of potassium, even though the atomic number of potassium is greater than the atomic number of argon.
(b) Deduce the numbers of protons and electrons in the K+ ion.
(c) Deduce the electron arrangement for the K+ ion.