In contrast, mole fraction, molality, and mass percentage depend on only the masses of the solute and solvent, which are independent of temperature. For many applications this may not be a problem, but for precise work these errors can become important. Because volumetric glassware is calibrated at a particular temperature, typically 20☌, the molarity may differ from the original value by several percent if a solution is prepared or used at a significantly different temperature, such as 40☌ or 0☌. How do chemists decide which units of concentration to use for a particular application? Although molarity is commonly used to express concentrations for reactions in solution or for titrations, it does have one drawback-molarity is the number of moles of solute divided by the volume of the solution, and the volume of a solution depends on its density, which is a function of temperature. \[moles\ CH_3CO_2H=\dfrac\) are in an 8 oz glass of water. The volume of the solution equals its mass divided by its density. We can calculate the number of moles of acetic acid as its mass divided by its molar mass. Then determine the mole fraction of acetic acid by dividing the number of moles of acetic acid by the total number of moles of substances in the sample.Ī The molarity is the number of moles of acetic acid per liter of solution.
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