Quantitative notation: Quantitative notation of concentration is far more informative and useful from a scientific point of view. There are a number of different ways to quantitatively express concentration; the most common are listed below. Unless otherwise stated, all the following measurements are assumed to be at standard state temperature and pressure that is, 25 degrees Celsius at 1 atmosphere. Mass percentage: denotes the mass of a substance in a mixture as a percentage of the mass of the entire mixture.
Commercial concentrated aqueous reagents such as acid and bases are often labeled in concentrations of weight percentage with the specific gravity also listed.
Mass-volume percentage is often used for solutions made from solid reagents. It is the mass of the solute in grams multiplied by one hundred divided by the volume of solution in milliliters.
This is most useful when a liquid — liquid solution is being prepared. This means every mL beer contains 5 mL ethanol ethyl alcohol. Molarity M : denotes the number of moles of a given substance per litre of solution. For instance: 4. This is often more useful when performing stoichiometric calculations. See molar solution for further information. Molality m : denotes the number of moles of a given substance per kilogram of solvent. For instance: 2. Volume increases with increase in temperature resulting in decrease in molarity.
Molality of a solution is always constant irrespective of the physical conditions like temperature and pressure. Normality N : Normality is a concept related to molarity, usually applied to acid-base solutions and reactions.
Normality is also used for redox reactions. In this case the equivalent is the quantity of oxidizing or reducing agent that can accept or furnish one mole of electrons.
Whereas molarity measures the number of particles per litre of solution, normality measures the number of equivalents per litre of solution.
In practice, this simply means one multiplies the molarity of a solution by the valence of the ionic solute. A bit more complex for redox reactions. Note: The normality is always equal to, or greater than the molarity for acid-base reactions. However, for redox reactions the normality is typically equal to or less than the molarity. Formal F : The formal F is yet another measure of concentration similar to molarity.
It is used rarely. 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. The value of the equivalents is always positive regardless of the charge.
Equivalents are used because the concentration of the charges is important than the identity of the solutes. For example, a standard IV solution does not contain the same solutes as blood but the concentration of charges is the same. What mass of sodium did the patient receive?
Note that if this problem had a different ion with a different charge, that would need to be accounted for in the calculation. Allison Soult , Ph. Department of Chemistry, University of Kentucky. Learning Outcomes Define concentration.
Use the terms concentrated and dilute to describe the relative concentration of a solution. Calculate the molarity of a solution. Use concentration units in calculations. Determine equivalents for an ion.
Complete calculations relating equivalents to moles, volumes, or mass. Complete dilution calculations. Percent Concentration One way to describe the concentration of a solution is by the percent of the solution that is composed of the solute.
Volume Percent The percentage of solute in a solution can more easily be determined by volume when the solute and solvent are both liquids. Parts per Million and Parts per Billion Two other concentration units are parts per million and parts per billion. Molarity 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.
Solution Step 1: List the known quantities and plan the problem. Step 2: Solve. Dilutions When additional water is added to an aqueous solution, the concentration of that solution decreases.
Add together the atomic masses from your solute to find the total molar mass. Divide the mass of the solute by the molar mass to find the number of moles. Be sure to subtract the mass of the container so you have an accurate reading. Moles are used to represent the number of atoms in the solution. Convert the volume of the solution to liters. Find the volume of the solvent before you mix in the solute. If your measurement is in milliliters, then divide it by 1, to convert it to liters.
If your solvent is already listed in liters, then you can skip this step. Divide the moles of solute by the volume of the solution in liters. Solve the equation and label the answer M. First, calculate the molar mass of your substance. Add the atomic masses of the constituent elements. Then, convert milligrams to grams by dividing by Finally, divide the grams of your substance by the Molar Mass. Not Helpful 8 Helpful Not Helpful 37 Helpful You can perform titrations.
Under the Le Chatelier's principle, the more concentrated one will have faster reacting time due to the fact that the more concentrated one has more molecules of that substance, leading to the ultimate truth that the chances of molecules meeting each other is bigger. Note that this method will not work if you are dropping Transition Metals into room-temperature, concentrated HNO3 or H2SO4 since Iron and other metals has the property called passivation. Not Helpful 13 Helpful Is it possible to learn chemistry when you are young?
I might be young but I'm smart. Yes it is certainly possible to learn chemistry at an early age - where there is interest, there is always a chance to learn well. Borrow books from your local library chemistry books are usually quite expensive or ask for a young person's book about chemistry or the elements for a birthday gift.
Keep notes of your learning and work your way up to doing safe experiments at home look for children's science experiment books in the library. You can also find chemistry apps for your tablet device. Not Helpful 28 Helpful Exactly 15 ml of glacial acetic acid is then added very slowly into the sodium acetate aqueous solution.
Finally, distilled water is added into the solution to fill the volume. Not Helpful 5 Helpful Not Helpful 4 Helpful 7. Include your email address to get a message when this question is answered. You do need to learn how to balance chemical equations with stoichiometry. Helpful 0 Not Helpful 0. Related wikiHows How to. How to. More References 6. Expert Interview. About This Article.
Co-authored by:. Chris Hasegawa, PhD. Co-authors: Updated: August 11, Categories: Featured Articles Chemistry Calculations. Article Summary X To calculate the concentration of a solution, start by converting the solute, or the substance being dissolved, into grams.
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