RTQ! This is one of the most common sources of errors in Chemistry examinations. When I sat 2014’s VCE Chemistry examination, I lost 5 marks in the paper for not reading the question! Your teachers will have told you to ‘read the question’ or ‘RTQ’ as well.
Task word errors can be avoided in two ways. First, learn the exact meanings of each task word. This is particularly important for EAL Chemistry students. Second, highlight the task words in a question (just as you would highlight the important information in a complicated titration question).
For example: “Explain how the different intermolecular forces in butane and butan-1-ol give these two compounds different boiling points. 3 marks”
In your answer, you will need to explain the effect of intermolecular forces. This means you’ll need to write why the butan-1-ol forms hydrogen bonds (due to the polar nature of the hydroxyl group) whereas butane forms only dispersion forces with its surrounding molecules (due to the non-polar nature of the molecule). You’ll also need to make some kind of comparison (which is hinted at by the word, ‘different’) in order to get all 3 marks.
Example 3-mark answer: “Butan-1-ol forms intermolecular hydrogen bonds with the surrounding molecules due to the polar nature of the hydroxyl group (O-H bond). Butane forms only dispersion forces with its surrounding molecules due to the non-polar nature of the molecule. Hydrogen bonds are stronger than dispersion forces and thus require more energy to break. This results in a higher boiling point for butan-1-ol than for butane”.
One mark would be awarded for each of:
- Explaining the intermolecular bonding of butan-1-ol
- Explaining the intermolecular bonding of butane
- Comparing the relative strengths of the two and relating this to boiling points
In a 2-mark answer, the student might omit the comparison step:
Example 2-mark answer: “Butan-1-ol forms intermolecular hydrogen bonds with the surrounding molecules due to the polar nature of the hydroxyl group (O-H bond). Butane forms only dispersion forces with its surrounding molecules due to the non-polar nature of the molecule.”
In a 1-mark answer, the student might only mention one of the two molecules, or might only make a comparison without explaining why these two compounds display different types of intermolecular forces.
Example 1-mark answer: “Hydrogen bonds formed by butan-1-ol are stronger than dispersion forces formed by butane and thus require more energy to break. This results in a higher boiling point for butan-1-ol than for butane”.
In that latter example, the student didn’t explain the reasons for the differences in intermolecular bonding – they merely stated them.
|Calculate||计算||Write the value of a number (include equations)|
|Compare||比较||Write the similarities and differences between|
|Evaluate||评价||Write arguments for and against|
|Define||确定||Write the exact meaning of|
|Describe||描述||Write details about (a thing or a process)|
|Discuss||讨论||Write reasons for and against|
|Distinguish||区分||Write the differences between two or more things|
|Explain||讲解||Write details to give the reader an understanding of|
|Find/State||写||Write (sometimes by doing calculations)|
|Identify||鉴定||Write which one|
|Illustrate||说明||Write something and draw a labelled diagram as well|
|Indicate||表明||Write which one (usually on a given diagram)|
|List||列出||Write a list|
|Outline||轮廓||Write a summary|
|Suggest||建议||Write a reason for a phenomenon|
|To what extent||到什么程度||Write whether a reaction is complete (→) or incomplete (↔).|
Watch task words in the examination… and make sure you answer the question!