What is the difference between dilute and aqueous

Sometimes, you may want to make a particular amount of solution with a certain percent by mass and will need to calculate what mass of the solute is needed. You can rearrange and solve for the mass of solute. The percentage of solute in a solution can more easily be determined by volume when the solute and solvent are both liquids. Frequently, ingredient labels on food products and medicines have amounts listed as percentages see figure below. It should be noted that, unlike in the case of mass, you cannot simply add together the volumes of solute and solvent to get the final solution volume.

When adding a solute and solvent together, mass is conserved, but volume is not. The mass-volume percent is also used in some cases and is calculated in a similar way to the previous two percentages. Two other concentration units are parts per million and parts per billion. These units are used for very small concentrations of solute such as the amount of lead in drinking water.

Understanding these two units is much easier if you consider a percentage as parts per hundred. Chemists primarily need the concentration of solutions to be expressed in a way that accounts for the number of particles present that could react according to a particular chemical equation. Since percentage measurements are based on either mass or volume, they are generally not useful for chemical reactions. A concentration unit based on moles is preferable. To calculate the molarity of a solution, you divide the moles of solute by the volume of the solution expressed in liters.

Note that the volume is in liters of solution and not liters of solvent. Calculate its molarity. The mass of the ammonium chloride is first converted to moles. Then, the molarity is calculated by dividing by liters.

Note that the given volume has been converted to liters. Having four significant figures is appropriate. When additional water is added to an aqueous solution, the concentration of that solution decreases. This is because the number of moles of the solute does not change, but the total volume of the solution increases. We can set up an equality between the moles of the solute before the dilution 1 and the moles of the solute after the dilution 2. Since the moles of solute in a solution is equal to the molarity multiplied by the volume in liters, we can set those equal.

Finally, because the two sides of the equation are set equal to one another, the volume can be in any units we choose, as long as that unit is the same on both sides. Our equation for calculating the molarity of a diluted solution becomes:. The solution has been diluted by a factor of five, since the new volume is five times as great as the original volume.

Consequently, the molarity is one-fifth of its original value. Another common dilution problem involves deciding how much a highly concentrated solution is required to make a desired quantity of solution with a lower concentration. The highly concentrated solution is typically referred to as the stock solution. Concentration is important in healthcare because it is used in so many ways. It's also critical to use units with any values to ensure the correct dosage of medications or report levels of substances in blood, to name just two.

Another way of looking at concentration such as in IV solutions and blood is in terms of equivalents. One equivalent is equal to one mole of charge in an ion. An aqueous solution is one where the solvent is water, regardless of the concentration of the dissolved solute s.

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