+ - Concentration Molarity (W) is defined as the number of moles of solute divid
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+ - Concentration Molarity (W) is defined as the number of moles of solute divided by the solution volume expressed in liters: molarity = moles of solute /volume of solution (L) For example, 1 M HCl contains 1 mol of HC1 dissolved in 1 L of the water. When a concentrated solution is diluted, the number of moles of solute stays constant: only the volume of the solution is changed. A dilution indicates an increase in solution volume and, therefore, the concentration of the solution must decrease. If you add more water to the HC1 solution considered above, so that now the volume is 2 L the number of moles remains the same but the volume is doubled. Hence the molarity of the solution is now 1 mol in a 2 L solution, that is, (1/2) M or 0.5 M. The number of moles of solute before and after dilution can be calculated by multiplying molarity times volume. We can set up the following equations: moles of solute = molarity x volume = M1,x vi = Mf x Vf where Mi is the initial molarity (of the concentrated solution). V is the initial volume. Mf is the final molarity (of the diluted solution), and Vf is the final volume. In the HC1 solution example the initial molarity is 1 M. the initial volume is 1 L, the final volume is 2 L, and the molarity is 0.5 M. Thus the number of moles present in these solutions is Part A The following five beakers, each containing a solution of sodium chloride (NaC1 also known as table salt), were found on a lab shell Arrange the solutions in order of decreasing concentration. Part B A student placed 16.5 g of glucose (C6H12O6) in a volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the 100 mL mark on the neck of the flask was reached. The flask was then shaken until the solution was uniform. A 25 0 mL sample of this glucose solution was diluted to 0.500 L. How many grams of glucose are in 100. mL of the final solution?Explanation / Answer
partA: beakers containing solution concentration decreasing order is 4>2>3>1>5.because beaker 4 has 3.25M,beaker 2 has 3.0M,beaker 3 has 2.16M,beaker 5&1 have same molar concentration i.e 1.5M but beaker 5 has less concentration than beaker 1 because dilution increases concentration decreases.
partB: the concentration of glucose in 100 ml of volumetric flask is 0.916M.25ml of this solution is diluted to 0.5L to get the solution containing 0.0458M.the weight of this glucose in 100ml of final solution is 0.825gr
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