How many grams of potassium hydrogen phthalate should be added to a 100 mL volumetric flask to prepare a 0.5000 M solution when the flask is diluted to the mark with water?
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102.11
To determine the number of grams of potassium hydrogen phthalate needed to prepare a 0.5000 M solution in a 100 mL volumetric flask, we need to consider the molar mass of potassium hydrogen phthalate and its molar concentration.
Here are the steps to calculate the required amount:
1. Identify the molar mass of potassium hydrogen phthalate (C8H5KO4). The molar masses of carbon (C), hydrogen (H), potassium (K), and oxygen (O) are approximately 12.01 g/mol, 1.01 g/mol, 39.10 g/mol, and 16.00 g/mol, respectively.
The molar mass of potassium hydrogen phthalate is calculated as follows:
(8 * C) + (5 * H) + K + (4 * O) = (8 * 12.01) + (5 * 1.01) + 39.10 + (4 * 16.00) = 204.23 g/mol
2. Use the molar mass to calculate the number of moles of potassium hydrogen phthalate needed.
moles = Molarity (M) * Volume (L)
moles = 0.5000 mol/L * 0.100 L = 0.0500 moles
3. Finally, convert moles to grams by multiplying moles by the molar mass of potassium hydrogen phthalate.
grams = moles * molar mass
grams = 0.0500 mol * 204.23 g/mol = 10.21 grams
Thus, to prepare a 0.5000 M solution in a 100 mL volumetric flask, you would need to measure approximately 10.21 grams of potassium hydrogen phthalate and add it to the flask before diluting it to the mark with water.