by Graeme Matthews

January 1, 2019

As I teach and tutor A level Chemistry I notice that some of my students find the maths used to solve chemistry problems easy to follow and others seem to find these types of problems the area where they lose the most points on their end of topic exams. They understand the concept being assessed in the question but get caught up in the maths – they forget to carry the minus sign, multiply by a coefficient or the units don’t cancel out. And before they know it, the question doesn’t make any sense anymore and they look at their paper with frustration!

Does one of these scenarios sound like you? Do you wish there was an easier way to solve these types of problems and achieve a good grade in A-level Chemistry?

POGIL – Sounds Weird But Makes Sense

POGIL is an acronym for Process Oriented Guided Instructional Learning. The process was formulated in the late 1990s as a way to teach General Chemistry in the United States. It sounds weird but once you see it in action it makes perfect sense! I find that once I teach POGIL to my students, it helps the students who like maths and don’t like maths get the correct answer to computational type problems all of the time.

All you have to do is complete the following steps:

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  1. Read the question carefully and underline any keywords or units.
  2. Circle the initial conditions.
  3. Circle the final conditions.
  4. Ask yourself “what steps do I need to complete in order to get from the initial conditions to the final conditions?”
  5. Write down any unit conversions that you may need to convert from one unit to the next.
  6. Make sure that the units cancel out as you move from one step to the next.

Solve Chemistry Problems: Example of POGIL In Action

solve chemistry problems

Here’s a sample problem you can solve using POGIL. It’s a type of problem that may be seen on the module on the amount of substance on Paper 1.

Q. How many chloride ions are present in 5.6 g of aluminium chloride?

Use POGIL to map out a path from the initial conditions to the final conditions.

  1. Initial condition: 5.6 g of aluminium chloride.
  2. Final condition: the amount of chloride ions.

Write down the steps you need to take in order to get from the initial to the final conditions:

  1. Compute the molar mass of AlCl3 which is 133 grams mol -1.
  2. Convert grams of aluminium chloride to moles of aluminium chloride.
  3. Recall that there are three moles of chloride ions per mole of aluminium chloride.
  4. Convert moles of aluminium chloride to moles of chloride ions.
  5. Recall that there is Avogadro’s number of chloride ions per mole of chloride ions.
  6. Convert moles of chloride units to units of chloride ions.

Graphically the process looks like this:

Screenshot 2018-12-27 at 07.44.25

By following the steps involved in POGIL when solving computational type problems my students get the correct answer the first time!

Are you considering hiring a tutor? Read the blog post “Hiring A Tutor For Your Child? 10 Factors To Consider Before You Decide“, for valuable information that will help you make the correct decision for your child.

About the author 

Graeme Matthews

Graeme Matthews has a B.Sc and an M.Sc in Chemistry and a PhD in Adult Education. He has been teaching a combination of university level, college and A-level chemistry for over 23 years. He has taught over 10,000 chemistry students in his teaching career. He has a proven track record of helping students earn an A* on their A-level chemistry exams so they can attend the university of their choice.

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