You need to make a 300 ml of a .37M Na2 SO4 solution. How much Na2 So4 should you weigh out?
How many moles do you need? That's mols = M x L = 0.37M x 0.300 L = ?
Then mols = grams/molar mass. YOu know mols and molar mass, solve for grams.
Also, check assay label for purity. If less than 100% pure, divide grams by fractional purity.
To determine how much Na2SO4 to weigh out, we need to use the formula:
Molarity (M) = moles (n) / volume (V)
First, we need to convert the desired volume of the solution from milliliters (ml) to liters (L):
300 ml ÷ 1000 ml/L = 0.3 L
Next, we can rearrange the formula to solve for moles (n):
n = M × V
Substituting the given values:
n = 0.37 M × 0.3 L = 0.111 moles
Finally, we can calculate the molecular weight of Na2SO4, which consists of two Na ions (22.99 g/mol each) and one SO4 ion (32.07 g/mol for S + (4 × 16.00 g/mol) for O):
Molecular weight (MW) of Na2SO4 = (2 × 22.99 g/mol) + 32.07 g/mol + (4 × 16.00 g/mol) = 142.04 g/mol
Now, we can determine the mass of Na2SO4 required:
Mass = moles × molecular weight
Mass = 0.111 moles × 142.04 g/mol ≈ 15.77 grams
Therefore, you should measure out approximately 15.77 grams of Na2SO4 to make a 300 ml of a 0.37 M Na2SO4 solution.