Calculate the mass of sodium hydroxide needed to prepare 500 mL of a 0.10 M solution. I'm pretty sure the answer is 2 grams, but how do I get to that?
answered below.
To calculate the mass of sodium hydroxide needed to prepare a solution, you can use the formula:
Mass (g) = Molarity (mol/L) x Volume (L) x Molecular weight (g/mol)
In this case, the given values are:
Molarity = 0.10 M
Volume = 500 mL = 0.5 L
First, convert the volume from milliliters to liters:
Volume (L) = 500 mL ÷ 1000 mL/L = 0.5 L
Next, find the molecular weight of sodium hydroxide (NaOH):
Na (sodium) = 23 g/mol
O (oxygen) = 16 g/mol
H (hydrogen) = 1 g/mol
Molecular weight (NaOH) = Na + O + H = 23 + 16 + 1 = 40 g/mol
Now, substitute the known values into the formula to find the mass of sodium hydroxide needed:
Mass (g) = 0.10 M x 0.5 L x 40 g/mol
Mass (g) = 2 g
Therefore, the mass of sodium hydroxide needed to prepare 500 mL of a 0.10 M solution is 2 grams.
To calculate the mass of sodium hydroxide needed to prepare a specific molar concentration solution, you need to use the formula:
Mass of solute (in grams) = molar concentration (in mol/L) * volume of solution (in L) * molar mass of solute (in g/mol)
Here's how to calculate the mass of sodium hydroxide needed to prepare a 0.10 M solution with a volume of 500 mL:
Step 1: Convert the volume to liters.
Since the molar concentration is given in mol/L, you need to convert the volume from milliliters (mL) to liters (L). Divide the volume by 1000:
500 mL ÷ 1000 = 0.5 L
Step 2: Determine the molar mass of sodium hydroxide.
Sodium hydroxide has the chemical formula NaOH. The molar mass can be calculated by summing the atomic masses of each element in the formula:
Na (sodium): 23.00 g/mol
O (oxygen): 16.00 g/mol
H (hydrogen): 1.01 g/mol
Molar mass of NaOH = (Na: 1 × 23.00 g/mol) + (O: 1 × 16.00 g/mol) + (H: 1 × 1.01 g/mol) = 39.01 g/mol
Step 3: Substitute the values into the formula and calculate the mass of sodium hydroxide.
Mass of solute (in grams) = 0.10 mol/L * 0.5 L * 39.01 g/mol
Mass of solute = 0.05 * 39.01 ≈ 1.95 grams
Rounding off to two significant figures, the mass of sodium hydroxide needed to prepare 500 mL of a 0.10 M solution is approximately 2 grams.