The higher level chemistry paper was challenging in parts and required plenty of higher order thinking skills, teachers have said.
Mary Mullaghy, ASTI chemistry representative and deputy principal at Eureka Secondary School in Kells, Co Meath, said analysis, synthesis and evaluation skills were needed.
“On both the ordinary and higher level papers, there was a strong emphasis on the link between chemistry and the real world. For example, question one looked at hardness in water, and question two looked at ethene as one of industry’s most important chemicals,” Ms Mullaghy said.
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Tara Lyons, a chemistry teacher at the Institute of Education, said much of the higher-level paper was made up of a series of very short, exact questions.
“Precision was the order of the day this year,” Ms Lyons said. “The topics examined were as in previous years and, if students had practised past papers, they would have been well prepared and should expect a good grade in August.”
Like last year, there was plenty of choice as students were required to answer just six questions — instead of the usual eight — due to the changes made to the paper as a result of Covid.
“Topics on the paper included atomic theory, volumetric analysis and organic chemistry, with a twist that students were asked about their experiments within the question,” she said.
She said question six — which focused on the fuels and heats of reaction — was a " salute, of sorts, to green energy.”
“Electric and hybrid cars were centre stage and there was also mention of the trial of hydrogen fuel-cell electric double deckers by Dublin Bus,” she said.
Ms Mullaghy added that there was lots of organic chemistry on the paper.
“The link between science, technology and society was evident in several parts of the paper, for example in question six, which examined fuel cells and electric cars,” she said.
Christopher Hegarty, a Teachers’ Union of Ireland subject representative, also said there was a good selection of questions.
“Question six, covering fuels and thermochemistry, links in information on hybrid electric cars and Dublin Bus testing electric fuel cells. This is a nice link to chemistry in society,” Mr Hegarty said.
“Questions three, seven and nine were fairly straightforward and would have pleased students who had revised well and were well prepared.”
On the ordinary level paper, Ms Mullaghy said that it was in line with previous years.
“There was sufficient choice to cater for everyone’s needs,” she said. “Question 11(d), however, might be regarded as a bit abstract for an ordinary level candidate.”
Try this one at home:
Leaving Cert chemistry, higher level
Question 6.: While electric and hybrid electric cars grow in popularity, two‐thirds of all new private cars licensed in Ireland between January and June 2021 were powered only by petrol or diesel. Petrol and diesel are mixtures of mostly hydrocarbons obtained from crude oil.
(a) Compare petrol (a mixture of light gasoline and naphtha) and diesel (gas oil) in terms of (i) average molecular mass of the hydrocarbons present, (ii) boiling point.
(b) (i) Explain the term octane number of a fuel. Give the systematic IUPAC name and draw the structure of a molecule of the alkane fuel (ii) assigned an octane number of zero, (iii) assigned an octane number of 100. (iv) What structural feature of the molecules of the alkane fuel assigned octane number 100 accounts for its high octane number?
