Question

Ideal Gas Law OR Types of Matter

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(5 points) Applying math to concepts is often problematic for chemistry students. A common error that I see when teaching is that students will exchange the unit labels that are in the numerator and the denominator without also moving the associated numerical value. Why do you think students resist moving the number when needing to use the reciprocal value as a conversion factor?

Answer 1

Students generally confuse to write the numerical calculating steps. In such cases it is better to guide them to write dimensions (units) along with the numbers given. As we know which ever unknown in the question that to be taken in the numerator. So if the students writes the relation from Unknown to known, he gets complete mathematical steps with out missing.

To explain this I can give you a small example.

If a question is there to convert 5.3 kg to pounds.

step:1 take all the unit conversions.

Since - 1 kg = 1000 g

1 pound = 453.6 g approximately.

HEnce - First we start from unknown. i.e., pounds (let "x" for example)

Now in step:2, take pounds in denominator to write grams to pounds conversions.

= (5.3 kg)(1000 g / 1 kg)(1 pound /453.6 g) = 11.7 pounds

I hope it helps....