Most specimens have high enough numbers of microorganisms that the specimen has to be serially diluted to quantitate effectively. Solution dilution basic lesson on solution dilution, plus a typical quiztest problem on the subject. The following is a stepbystep procedure to working dilution problems, and includes some practice problems at the end. The properties and behavior of many solutions depend not only on the nature of the solute and solvent but also on the concentration of the solute in the solution. Serial dilution practice problem set science primer. To get around this problem, solutions are often described by their solute concentration using the molar designation.
The first dilution is made just like the simple dilution. The easiest method is to make a series of 1 in 10 dilutions. Serial dilutions are often performed in steps of 10 or 100. When we said the diluted coffee was 110th as strong as the original that was a dilution factor. There are three formulas used to work microbiology dilution problems. Preparing solutions and making dilutions simple dilutions mixing parts or volumes. Concentrations and dilutions answer key some of the worksheets for this concept are dilutions work, dilutions work, dilutions work name key, dilutions work w 329, concentrations and dilutions, molarity and serial dilutions teacher handout, laboratory math ii solutions. Calculate mathematical manipulations and problems for basic math, the metric system, and dilutions.
We could also have said the dilution factor was 110, or the dilution factor was 0. Serial dilutions are useful in a small quantity of serum and to find the titer of antibodies. A serial dilution is any dilution in which the concentration decreases by the same factor in each successive step. The solution has been diluted by onefifth since the new volume is five times as great as the original volume. Dilution worksheet and problems biology libretexts. Another common dilution problem involves deciding how much of a highly concentrated solution is required to make a desired quantity of solution of lesser concentration. To find a dilution of a single tube, use the formula. Lab math solutions, dilutions, concentrations and molarity. Make a dilution of 1 part serum and 9 parts saline. A serial dilution is any dilution in which the concentration decreases by. While serial dilutions are a great way to save on both reagents and space in the lab. To determine the concentration you multiply the number of colonies by the inverse of the dilution factor in flask b it was 104.
In serial dilutions, you multiply the dilution factors for each step. This webinar is intended to give a brief introduction into the mathematics of making solutions commonly used in a research setting. How to work microbiology dilution problems sciencing. Serial dilutions are made by making the same dilution step over and over, using the previous dilution as the input to the next dilution in each step. A solution in which water is the solvent is called an aqueous solution. Concentration is the removal of solvent, which increases the. Serial dilution preparation preparation of a solution of lower concentrat olution y,%t 878 1. An easy learning guide serial dilution is the stepwise dilution of a substance in a solution. When youre thinking about dilution, it helps to simplify your actions into.
This example shows three different types of ways a solution stoichiometry question can be asked, using molarity, stoichiometry and dilutions. Molarity dilution problems solution stoichiometry grams, moles, liters volume calculations chemistry duration. Dilution calculations from stock solutions in chemistry. Concentrations and dilutions answer key kiddy math. The following successive dilutions are applied to a stock solution that is 5. The dilution factor or the dilution is the initial volume divided by the final volume. To determine the final concentration of your solution following serial dilution you will need to know your starting concentration. Molarity dilution problems solution stoichiometry grams, moles. This is a chemistry tutorial that covers dilution problems, including examples of how to calculate the new concentration of a diluted solution, and how to ca. This is defined as multiple progressive dilutions ranging from a more concentrated solution to a less concentrated solution. If the dilution factor is larger than the final volume needed, or the amount of stock is too small to be pipetted, one or more intermediary dilutions may be required. A set of serial dilutions is made, a sample of each is placed into a. The equation is c final c initial d where c final is the ending concentration of the diluted solution, c initial is the starting concentration of the original solution and d is the dilution ratio previously. This process keeps the amount of solute constant, but increases the total amount of solution, thereby decreasing its final concentration.
A dilution is a solution made by adding more solvent to a more concentrated solution stock solution, which reduces the concentration of the solute. An easy learning guide solutions or growing an acceptable number of bacterial colonies to count. How to calculate concentrations when making dilutions. An example of a dilute solution is tap water, which is mostly water solvent, with a small amount of dissolved minerals and gasses solutes. This cannot be done with a fluid solution since 1 one cannot identify purity.
A serial dilution is a series of sequential dilutions used to reduce a dense culture of cells to a more usable concentration. Serial dilutions are widely used in experimental sciences, including biochemistry, pharmacology, microbiology, and. Dilutions are governed by this equation, the product of the starting concentration, times the starting volume. Solutions part 1 solutions used in clinical laboratory. Dilutions and concentrations introductory chemistry. A very quick lesson on how to do the math for serial and simple dilutions. A serial dilution is a series of simple dilutions which amplifies the dilution factor quickly. This is a collection of worked general chemistry and introductory chemistry problems, listed in alphabetical order. When youre thinking about dilution, it helps to simplify your actions into dilution factors.
Dilutions of solutions introduction to chemistry lumen learning. The weight of sugar in each solution is the same, but there are twice as many sugar molecules in the glucose solution. Concentrations part 5 serial dilution fifth video in a series of videos discussing concentration calculations commonly used in. The first five statements are symbolically shown as 110 dilutions and the last three are shown as 1. Serial dilution is a series of sequential dilution of a substance in solution. The purpose can be determination of bacterial, fungal, or viral counts indirectly. Molarity, solution stoichiometry and dilution problem. While you may already make solutions in the lab by following recipes, we hope this webinar will help you understand the concepts involved so that you can.
A serial dilution is a series of stepwise dilutions, where the dilution factor is held constant. Dilutions worksheet 1 if i add 25 ml of water to 125 ml of a 0. Simple dilution problems the most common type of dilutions done in chemistry lab involve taking a sample of a solution of known volume and concentration and diluting it to some larger volume. The following problem sets test your ability to calculate dilution factors and concentration s. Pharmacy dilution math is a process of reducing the concentration of a solution by adding more solvent. Dilutions worksheet w 329 everett community college student support services program 1 if 45 ml of water are added to 250 ml of a 0. Instead, they make concentrated stock solutions and then make dilutions of those stocks as necessary for a given experiment. The answers i sure hope you tried to answer the problems before you looked here. The formulas explained here are only to be used for the purpose of diluting a solution from a higher percentage to a lower percentage. Chemists use many different units when expressing concentration.
Serial dilution problems read carefully and show a. They are described as ratios of the initial and final concentrations. Chapter six concentrations and dilutions 29 now this problem has given us the final concentration, and we are being asked to determine the amount of active ingredient needed. Consequently, the molarity is onefifth of its original value. Often, a worker will need to change the concentration of a solution by changing the amount of solvent. The analytical equipment available to shelby in the lab includes the volumetric flasks and pipettes shown. The important thing to remember is that the amount of solute doesnt change during the dilution process, only the amount of solvent and therefore, of. To make a dilution, you simply add a small quantity of a concentrated stock solution to an amount of pure solvent. A serial dilution is simply a series of simple dilutions which amplifies the dilution factor quickly beginning with a small initial quantity of material e. Solutions in which water is the solvent are, of course, very common on our planet.
These methods are shortcuts to algebra methods and should only be used for taking the pharmacy tech test. Dilutions worksheet w 329 everett community college. As well as possible errors and how they can be avoided. Serial dilution problems read carefully and show all work. Usually, the dilution factor at each step is constant, resulting in a geometric progression of the concentration in a logarithmic fashion. Notice that, in essence, the previous examples could be solved by using the formula below. I know the final molarity that i would like, that was in the problem, and i know the final volume i would like, that is in the problem. Included are printable pdf chemistry worksheets so you can practice problems and then check your answers.
On the next couple of slides, we will be going through some practice problems in. Up until this point, we have been able to solve for the final % strength by. A serial dilution is simply a series of simple dilutions which amplifies the. This chemistry video tutorial explains how to solve common dilution problems using a simple formula using concentration or. This tutorial describes how dilutions are made from stock solutions, and how to calculate the volume of stock solution required for a given final concentration. Serial dilutions are used to accurately create extremely diluted solutions, as well as solutions for experiments that require a concentration curve with an exponential or logarithmic scale. If one ml was spread on plate a it would be x 10 4 or 000 or 1. What are some limitations to a serial dilution lab.
A solute is a component of a solution that is typically present at a much lower concentration than the solvent. To dilute a stock solution, mix the stock solution with diluent. You may also browse chemistry problems according to the type of problem. Dilution is the addition of solvent, which decreases the concentration of the solute in the solution.