A scientist wants to make a solution of tribasic sodium phosphate, Na_3PO_4, for a laboratory experiment. How many grams of Na_3PO_4 will be needed to produce 375 mL of a solution that has a concentration of Na^+ ions of 1.10M?
I tried multiplying .375 L by 1.10 M to get the number of moles, but I don't know if I'm doing this correctly. I got 0.4125 mols. Then am I supposed to convert this to grams? I feel like the moles number should be bigger.
There are two or three ways of starting and yours is as good as any. What you have done is ok. I assume you need help with the next step.
moles = M x L and 0.4125 moles is correct. But note that this is moles Na^+ and NOT Na3PO4. So moles = grams/molar mass or grams = moles x molar mass. Thus, grams = 0.4125 x molar mass Na3PO4 will give you the grams of Na3PO4. Since there are 3 Na^+ for every mole of Na3PO4, you want to divide this number by 3. You can check to see if this number is right by dividing grams Na3PO4 by molar mass, and dividing that by 0.375 to obtain molarity Na3PO4. Then multiply by 3 to obtain molarity Na^+.
A scientist wants to make a solution of tribasic sodium phosphate,
Na3PO4, for a laboratory experiment. How many grams of Na3PO4 will be
needed to produce 475 mL of a solution that has a concentration of Na^+
ions of 0.800 M?
Express your answer numerically in grams.
mass of Na3PO4 =
0.8g
To determine the number of grams of Na3PO4 needed to produce a 375 mL solution with a concentration of Na+ ions, you first need to calculate the number of moles required.
First, convert the volume from milliliters (mL) to liters (L):
375 mL = 375/1000 L = 0.375 L
Next, you correctly multiplied the volume (in liters) by the concentration (in moles per liter) to calculate the number of moles of Na+ ions:
0.375 L * 1.10 mol/L = 0.4125 mol Na+ ions
Now, we need to account for the stoichiometry of Na3PO4 to determine the number of moles of Na3PO4 required. From the chemical formula of Na3PO4, we can see that there is one Na+ ion for every formula unit of Na3PO4. This means that the number of moles of Na+ ions is equal to the number of moles of Na3PO4.
Therefore, 0.4125 mol of Na+ ions is also equal to 0.4125 mol of Na3PO4.
Finally, to convert the number of moles of Na3PO4 to grams, you need to use the molar mass of Na3PO4. The molar mass of Na3PO4 can be calculated by summing the atomic masses of sodium (Na), phosphorus (P), and oxygen (O) in the formula:
Molar mass of Na3PO4 = (3 * atomic mass of Na) + atomic mass of P + (4 * atomic mass of O)
Using the atomic masses from the periodic table:
Molar mass of Na3PO4 = (3 * 22.99 g/mol) + 30.97 g/mol + (4 * 16.00 g/mol) = 163.94 g/mol
Now you can calculate the mass of Na3PO4 needed by multiplying the number of moles by the molar mass:
Mass of Na3PO4 = 0.4125 mol * 163.94 g/mol = 67.51 grams
Therefore, 67.51 grams of Na3PO4 will be needed to produce a 375 mL solution with a concentration of Na+ ions of 1.10M.