Molarity & Dilution Calculations

The practice site now has a solutions unit.  While the lessons are still in production, the practice problem modules are complete.  You can now try unlimited practice problems for calculating molarity and for calculating dilutions.

The practice problems can be found by going to the practice site,, the choosing "Unit 12-Solutions" from the drop-down menu.  Choose the lesson in which you are interested on the right - then push the button on the right for unlimited practice problems.  The topics with practice problems currently available are:  Calculating Concentration and Calculating Dilutions.

When complete, the solutions unit will include lessons and practice problems covering ten (10) topics, including such things as the special properties of water, solubility, solubility curves, electrolytes, and colligative properties.

If you use it, don't forget to like the page.

Stoichiometry Practice Website is Online

There is a new website associated with HaltomScience, it is  Users there can select Grams-to-Grams Stoichiometry problems, or the more complicated Limiting Reactant problems.

The users are presented with one given in the first option, and must calculate the grams of product produced by the reaction.  In the second case, the user is presented with two different givens - one for each reactant.  A random product is selected, and the user then has to calculate the grams produced from each given.  The smaller of the two is the limiting reactant, and the user must enter that value in one field.  The user also has to calculate how much of the excess reactant is used and subtract that from the given to arrive at the amount of excess reactant left over.

This is the sort of problem found in limiting reactant problems in general chemistry.  The site generates random problems from over 60 possible chemical reactants and random values for the givens, so there are virtually unlimited combinations of problems that are provided.

The user must select a teacher and enter their name in order to get credit if the teacher has assigned problems for credit.  If the user is just their for practice, the need to select "Guest Student" as their teacher's name.

Correct and incorrect answers are saved so that the teacher can see how many problems have been attempted and provide appropriate credit.  No grades are provided by the website, but it does indicate if the answer is correct.  If the answer is incorrect, the correct answer is shown so the user can figure out their mistakes.

The website was written by the author (William Franz), a Chemistry teacher at Haltom High School.  It was written and completed over the weekend of March 5-6, 2016, in php code.  The next project is a gas laws practice problem generator.

Welcome to FranzScience

This is the blog site for Mr. Franz Science Classes.  It will contain posts about new resources developed by Mr. Franz for science education.

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