Solutions and Concentrations

Overview

Source: Laboratory of Dr. Michael Evans — Georgia Institute of Technology

A solution is a homogeneous mixture containing some components in small amounts, called solutes, and one component in a large amount, called the solvent. Solid-liquid solutions contain one or more solid solutes dissolved in a liquid solvent. Solutions are ubiquitous in chemistry: they are used to store and handle small amounts of material, carry out chemical reactions, and develop materials with controllable properties.

The density of a solute in a solution is known as the concentration of the solute. Concentration can be expressed in several ways, differing in the units used to convey the amounts of solute, solvent, and solution.

This demonstration illustrates how to prepare a sucrose solution with a target concentration using precise analytical techniques. Additionally, various measures of the concentration of this solution are presented and explained.

Procedure

1. Preparation of 100 mL of a 0.0100 M Sucrose Solution

Determine the number of moles and mass of sucrose (C₁₂H₂₂O₁₁) to be dissolved in 100 mL of solution.
Weigh out the mass of sucrose on the balance. First place a weigh boat on the balance and set the “tare weight”. Then using a scoopula, carefully transfer solid solute from the reagent bottle to the weigh boat until the desired

Results

Procedure step 1 creates 100 mL of a 0.0100 M sucrose solution. To convert to measures of concentration other than molarity, determine the mass of water used to prepare the solution. Although this can be measured accurately, in the absence of a measurement it can be assumed that the volume of dissolved solute particles is negligible (i.e., the volume of water used was 100 mL). Using the density of water…

Equation 7

Application and Summary

Solid-liquid solutions are ubiquitous in chemistry. Most chemical reactions are run in solution because dissolved solutes are mobile enough to rapidly mix and bump into one another. Solutions can also be used to store small amounts of solutes in macroscopic and easily handled volumes. Solutions exhibit some interesting physical properties called colligative properties that can be attributed to the entropic effects of dissolving a solute in a solvent.

One may wonder why so many different measur