Calculate the weight of anhydrous Na2CO3 necessary to prepare M/20 solution in 100cm3 volumetric flask
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To calculate the weight of anhydrous Na2CO3 necessary to prepare a M/20 solution in a 100 cm3 volumetric flask, we need to follow these steps:
Step 1: Determine the molar mass of Na2CO3.
The molar mass of Na2CO3 is calculated by adding the molar masses of its constituent elements: sodium (Na), carbon (C), and oxygen (O). Using the periodic table, we find the molar masses to be as follows:
Sodium (Na): 22.99 g/mol
Carbon (C): 12.01 g/mol
Oxygen (O): 16.00 g/mol
Calculating the molar mass of Na2CO3:
(2 * Na) + C + (3 * O) = (2 * 22.99 g/mol) + 12.01 g/mol + (3 * 16.00 g/mol)
= 45.98 g/mol + 12.01 g/mol + 48.00 g/mol
= 105.99 g/mol
Step 2: Convert M/20 to mol/dm3.
A M/20 (molar) solution means that there are 1/20th (or 0.05) mole of Na2CO3 present in 1 liter of solution.
Therefore, M/20 = 0.05 mol/dm3.
Step 3: Calculate the number of moles required for a 100 cm3 (0.1 dm3) solution.
We can use the equation:
moles = concentration (mol/dm3) * volume (dm3)
moles = 0.05 mol/dm3 * 0.1 dm3
moles = 0.005 mol
Step 4: Calculate the weight of Na2CO3 required.
Now that we have the number of moles required, we can calculate the weight using the molecular weight of Na2CO3:
Weight (g) = mole * molar mass
Weight (g) = 0.005 mol * 105.99 g/mol
Weight (g) = 0.52995 g
Therefore, approximately 0.53 g of anhydrous Na2CO3 is required to prepare a M/20 solution in a 100 cm3 volumetric flask.