2 Chemistry and Math Review
Soil science, as with any science, involves collection and interpretation of data. In order to appropriately record and interpret data in this course, students must have a fundamental understanding of unit conversions and chemistry. This lab will review some of the major concepts that are essential for success in Soils.
Learning Objectives
- Review basic chemistry and math skills that will be used throughout the semester.
Materials
- Chemistry and Math for Soil Scientists Problem Set
Recommended Reading
Prelab Assignment
Using a chemistry textbook, and the conversion factors and formulas provided in this laboratory manual, consider the following questions.
- Define dimensional analysis. Describe how it can be useful for unit conversion, and how it can be used to check the accuracy of calculations.
- Define molarity and give several examples of how it can be expressed (labels or units).
- Describe, in general terms, the process of an acid-base titration.
- Note if any of the units listed in under Conversion Factors and Formulas are unfamiliar to you. If so, look that unit up and describe it in terms of units with which you are familiar.
- Are the units “Mg” and “mg” the same? If not, which one is larger?
- How many dimensions are there in the following units? Label each unit as a length, area, or volume.
- m:
- m2:
- m3:
Introduction
Dimensional Analysis
Quite often, our measurements are not in the same units in which we wish to express our results. However, converting from one measurement to another is not difficult with the correct conversion factors. The key is appreciating that different units can be used to express the same amount. Calling a sofa by another name like couch does not change anything about that piece of furniture, nor does expressing a person’s height in in instead of feet make them any taller or shorter. So by changing units, we do not change the amount, just the name we use to express that amount.
This is based on the principle that if we multiply any number by one, it does not change the number. For instance, we know that one hour is equal to 60 minutes, and that one minute is equal to 60 seconds. Consider the following fraction:
[latex]\frac{60\text{ minutes}}{60\text{ minutes}}[/latex]
We know that this fraction reduces to one because the top (the numerator) is equal to the bottom (the denominator). However, we know that 60 minutes is equal to one hour. So we could write the fraction:
[latex]\frac{60\text{ minutes}}{1\text{ hour}}[/latex]
While the numerical value of this fraction is 60, the amount of time represented in both the numerator and denominator are equal, and this fraction is, in a sense, equal to one. We use this concept, most likely without thinking about it, when we convert certain quantities in our head. If told that something will take about two hours, we can immediately convert this in our head to 120 minutes. Or if we need to be somewhere in half an hour, we can convert this to