# Reference Guides

### Introduction

A solution is described as a homogeneous mixture of a solute and a solvent. The term solution is commonly applied to a liquid, however, a solution can also be made using gas solids.

The purpose of preparing a solution is to make the drug easier to administer to the patient. Preparing a solution is done by dissolving a known mass of solute (often a solid) into a specific amount of a solvent. The most common way to express the concentration of the solution is M or molarity, which is moles of solute per liter of solution.

### Guide

In this example, we will be preparing a solution of Vitamin B12 dissolved into Water.

First, calculate the molar mass of Vitamin B12 (Molecular Formula C63H88CoN14O14P) which is the mass of a mole of all elements in the molecular formula. You can find the mole on nay periodic table (It is the number located beneath the element).

Example: C 756.7 + H 88.7 + Co 58.93 + N 196.09 + O 223.99 + P 30.97= 1355.36 g/mol

• • Weigh out 1355.36 g Vitamin B12.
•

• • Place the Vitamin B12 in a 1-liter volumetric flask.
•

• • Add a small volume of distilled, deionized water to dissolve the Vitamin B12.
•

• • Fill the flask to the 1 L line.

If different molarity is required, then multiply that number times the molar mass of Vitamin B12. For example, if you wanted a 0.5 M solution, you would use 0.5 x 1355.36 g/mol of Vitamin B12 in 1 L of solution or 677.68 g of Vitamin B12.

### Conclusion

Solutions are an integral part of pharmaceutical science as they provide a safe vehicle with which to administer the chemical.