How many grams of solute are in each of the following solutions?
18.4 mL of a 9.50 m H3PO4 solution
To determine the number of grams of solute in the 18.4 mL solution of 9.50 m H3PO4, we need to follow a few steps:
Step 1: Calculate the molar mass of H3PO4.
The molar mass of H3PO4 is calculated by adding up the atomic masses of each element in the compound. Here's how to calculate it:
H3PO4:
H: 1.01 g/mol (hydrogen atomic mass)
P: 30.97 g/mol (phosphorus atomic mass)
O: 16.00 g/mol (oxygen atomic mass)
Molar mass of H3PO4 = (3 * 1.01 g/mol) + (1 * 30.97 g/mol) + (4 * 16.00 g/mol)
= 3.03 g/mol + 30.97 g/mol + 64.00 g/mol
= 98.00 g/mol
Step 2: Convert mL to L.
To perform calculations with molarity, it's necessary to use the volume in liters instead of milliliters. To convert mL to L, divide the volume (18.4 mL) by 1000:
18.4 mL ÷ 1000 = 0.0184 L
Step 3: Calculate the number of moles of solute.
The molarity (m) of a solution is defined as the number of moles of solute (mol) divided by the volume of the solution in liters (L).
Molarity (m) = moles of solute (mol) / volume of solution (L)
Rearranging the formula to solve for moles of solute:
moles of solute (mol) = Molarity (m) × volume of solution (L)
moles of solute (mol) = 9.50 mol/L × 0.0184 L
moles of solute (mol) = 0.1748 mol
Step 4: Convert moles to grams.
To convert moles of H3PO4 to grams, we need to multiply the number of moles by the molar mass of H3PO4:
Grams of solute = moles of solute (mol) × molar mass of H3PO4 (g/mol)
Grams of solute = 0.1748 mol × 98.00 g/mol
Grams of solute ≈ 17.11 g
Therefore, there are approximately 17.11 grams of solute in the 18.4 mL of a 9.50 m H3PO4 solution.