The modern periodic table has been at the heart of chemistry, biology, and other sciences since the pioneering work of Meyer and Mendeleev in the mid-1800s. A periodic table has graced the inside front cover of countless science texts for as long as I can remember, but textbooks don't always do such a good job of explaining what it is and how to use it.

Unlike these static textbook tables, the Periodic Table Cramlet™ has several features that make it effective where the book is not:

The Periodic Table is one of our most popular Cramlets™. Of the features listed here, the best one is that, unlike a textbook, it is available for free to every student who signs up for a free registration.

Dear Professor Cram:

How many grams of NaCl would you dissolve in water to make a 0.5 M NaCl solution with 500 mL final volume? What are the steps in finding the answer?

Anneka L.

Thank you for using College-Cram.com and for your chemistry question.

This requires a multi-step process to determine the answer. First, we need to note that the "M" in a 0.5 M NaCl solution means there are 0.5 moles of NaCl per 1 liter of solution. Since there is in fact only 500mL of solution (i.e., half a liter), you really have only 0.25 moles of NaCl (half of 0.5).

Next, you can use our Mole Conversions Cramlet™ to find how many grams it takes to produce this solution. Using your Periodic Table, you can determine the molar mass of one mole of NaCl by adding the atomic masses of the two elements:

• 22.98977 + 35.453 = 58.44277 grams/mole

Now multiply this by the number of moles of NaCl you have (0.25, as we found above) to find the number of grams of NaCl we needed to start with:

• (58.44277 grams/mole)(.25 moles) = 14.611 grams

I hope this helps. Let us know if you need anything else.