Please answer part 1 & 2 of question Since the number of molecules of a particular solute is impossible to count we can use the Molecular Weight of thesolute to get to it. Each atom and therefore molecule has a particular mass. The mass in grams of one mole of asubstance is its Molecular Weight (MW).Molecular Weight (the weight of one mole of a particular molecule or atom): MW = g/moleThe Molecular Weight of a chemical is usually given on the bottle, but can also be calculated using the periodictable of elements. The atomic mass for every element is listed underneath the symbol for that element in theperiodic table, and for a chemical, the atomic mass for each component of that chemical, added together, will givethe Molecular Weight for that chemical.For example, sodium chloride has a chemical formula of NaCl. According to the periodic table, Na (sodium) hasan atomic mass of 22.99 and CI (chlorine) has an atomic mass of 35.45. NaCl therefore has a Molecular Weight of22.99 +35.45 = 58.44. Remember that the Molecular Weight is measured in g/mole. 6.022 x 1023 molecules (1mole) of NaCl thus weigh 58.44 g.Now, this is not a concentration yet, since we have not dissolved anything in a solvent. Molarity isa measure of a number of molecules in 1 liter of solution. By definition, a 1 molar solution has 1 mole of the soluteper 1 liter of solvent. To make a solution of NaCl that is 1 molar (1 M), we therefore need to dissolve the 58.44 g ofNaCl from above in a total volume of 1 liter.If you have the amount of solute (mass) and the volume, but need to know the Molarity, you can use the followingequation:M (mole/liter) = weight of solute (g)V (liter) * MW (g/mole)Generally, to prepare 1 liter of a simple molar solution from a dry reagent you have to multiply the MolecularWeight by the desired Molarity to determine how many grams of reagent to use. This is the equation above, justrearranged.Needed weight in g to dissolve in 1 liter = MW (g/mole) * M (moles/liter)It is very important that you always use the correct and complete units for these calculations since they can tell youat a glance whether your formula is wrong. For example, if you want to know how many g of NaCl to weigh out tomake a 1 M solution, your units, when canceled out, should leave you with grams. Don't forget that Molarityalways refers to 1 liter. If you want less or more than 1 liter of your solution this will have to be factored into theequation.Needed weight in g to dissolve in desired volume = MW (g/mole) * M (moles/liter)* desired volume (liter)Example:If you want to make 250 ml of a 2 M NaCl solution:58.44 g/mole * 2 moles/liter* 0.25 liter = 29.22. To make this solution properly you would weigh out29.22 g of NaCl, dissolve it in about 200 ml of water and then fill the total volume to 250 ml with water.Why would you not pour the 29.22 g directly into 250 ml of water and then dissolve?Skills Boot Conp / Similarly, for liquid solutes, volume of solute to use = % concentration * volume neededExample: if you want to make 2 liters of a 10% hydrogen peroxide solution you would mix 10 ml/100 ml x2000 ml = 200 ml of hydrogen peroxide with 1800 ml of water.It's your turn..Exercise 1: You got a job as an adjunct instructor at a community college and want to make 320 ml of a 2%maltose solution for one of your students' lab experiments, How much maltose would you need?3. Weight/volume (w/v):You find this quite often in sciences as well. For analyses where ppm, ppb, % etc. do not apply, this is a good wayto indicate concentration. Solutes dissolved in blood, for example, are often indicated as weight per volume.Acceptable levels of total cholesterol, for example, are 150-200 mg/dl (a deciliter being 1/10th of 1 liter).Example: if you take the example from the previous page, your 200 ml of 4% maltose solution (8 g in 200 ml)can also be expressed as a 40 g/liter sugar solution.4. Molarity (M)This measure of concentration is most commonly used for laboratory solutions and often the hardest for students tomaster. In chemistry and biology, it is often important to have a measure of the number of molecules in a givenvolume of solution, not just a measure of percent or weight/volume. We will encounter this again when we talkabout pH, for example. So what is Molarity? Molarity (M) describes the number of molecules (in this case, aspecific number of molecules or moles) of a chemical in one liter of solution. Similar to the formula for percentabove,c=n/vMolarity can be calculated bywhere the concentration (c) is Molarity and instead of mass of a chemical we measure the number of moles (n) ofthis chemical per volume (v).Molarity (describes a concentration as a number of molecules/volume): M= moles/literSo what is a mole? The key word is number and like a baker's dozen, a mole is just that, a number, albeit a veryhigh one: 6.022 * 1023. A 1 molar solution (1 M) of sucrose therefore would contain 6.022 * 1023 molecules ofsucrose per liter.1 mole (number of molecules or atoms) = 6.022 * 102313Basic Lahoroen Stills Boot Cany

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Answered: Exercise 1: You got a job as an adjunct…

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...