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Molarity |
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Chemistry Made Easy With "Professor" Schwartz Molarity Molarity Many Chemical reactions take place in a solution. Molarity is one of the most common methods of expressing the relationship between a dissolved substance and the solution its in. Molarity- The ratio between the moles dissolved in a substance and the volume of solution in cubic decimeters. The common equation for molarity is M = moles of solute dm3 of solution **Remember**1dm3 = 1L = 1000mL = 1000cm3 Now by following my steps you should be able to solve these problems in about 1 minute, Tops! Follow these steps in the example. What is the molarity of a solution of KNO3 that contains 606g of KNO3 in 2.00 liters of solution? STEP 1 Find the molar mass of KNO3 The molar mass is the same as the atomic mass only in grams. The molar mass of these elements are located on the periodic table of elements. K = 39.0 **notice that Oxygen is mult. by three there for this must be done to all elements with exponents N = 14.0 3O= 16 x 3 = 48
STEP 2 Add the masses together and then divide this into the mass given. This gives you your moles. K = 39.0 N = 14.0 = 101 606/101 = 6 moles 3O = 48
STEP 3 Now just use the formula to find the molarity. The rest of the problem is clear sailing. M = moles of solute/ dm3 of solution M = 6 moles / 2.00liters M = 3 Here are some more problems to try your hand at. 1) Find the molarity of 8.55g NH4I in 50.0cm3 of a solution.
2) Find the molarity of 5.23g of Fe(NO3) in a 100cm3 of a solution.
3) Calculate the molarity of a solution containing 10.0g of sulfuric acid (H2SO4) in a 500 ml solution.
4) What Is the molarity of a 3.00Liter solution made with 120g of MgO
5) What would the volume of a 2.00M solution of KOH that was made with 60.0g of solute?
Answers 1) 1.18M 2) 0.291M 3) .204g/ml 4) 1.0M 5) .525L Please forward all questions, comments and criticisms to Gregory L. Curran. |
