what mass of NaOH would be needed to neutralize exactly 200cm3 of a solution containing 4.9g per dm3 of H2SO4
2NaOH + H2SO4 ==> Na2SO4 + H2O
mols H2SO4 = grams/molar mass = 4.9/98 = 0.05
The equation tells you you will need twice that number of mols of NaOH or 2 x 0.05 = 0.1 mol
Then grams NaOH = 0.1 mol x 40 g/mol = 4.0 grams NaOH.
Note that you don't need the 200 cc UNLESS you change H2SO4 to concentration and I didn't do that. Another way of saying that the grams NaOH needed is grams H2SO4 initiall and it makes no difference how much solvent is used.
2NaOH + H2SO4 ==> Na2SO4 + H2O
You have 200 cc H2SO4 containing 4.9 g/L so that is
4.9 g x 200 cc/1000 cc = 0.98 grams H2SO4.
0.98 grams x (1 mol/98 g) = 0.01 mol H2SO4.
So you know you will need 2 x 0.01 = 0.02 mol NaOH and that will be 0.02 x 40 = ? g NaOH.
Check this. Make sure I didn't make an error AND that I read the problem correctly.
OOPS. After posting my answer above I re-read the question and is DOES make difference so I'll post a new answer below. Sorry about that.
To determine the mass of NaOH required to neutralize the given solution, we need to follow these steps:
Step 1: Determine the number of moles of H2SO4 in the solution.
- First, convert the given concentration of H2SO4 from grams per decimeter cubed (g/dm^3) to grams per cubic centimeter (g/cm^3). Since 1 dm^3 equals 1000 cm^3, the concentration is 4.9 g/dm^3 = 0.0049 g/cm^3.
- Next, calculate the number of moles of H2SO4 using its molar mass. The molar mass of H2SO4 is 98.09 g/mol. Therefore, the number of moles of H2SO4 can be determined by dividing the mass by the molar mass:
moles of H2SO4 = mass of H2SO4 / molar mass of H2SO4
Step 2: Apply the balanced chemical equation for the neutralization reaction between H2SO4 and NaOH.
- The balanced chemical equation for the reaction is:
H2SO4 + 2NaOH -> Na2SO4 + 2H2O
- From the equation, we can see that one mole of H2SO4 reacts with two moles of NaOH.
Step 3: Determine the mass of NaOH required to neutralize the solution.
- Since one mole of H2SO4 reacts with two moles of NaOH, we can use this ratio to find the number of moles of NaOH required:
moles of NaOH = (moles of H2SO4) * 2
- Finally, calculate the mass of NaOH by multiplying the number of moles by its molar mass (39.997 g/mol for NaOH):
mass of NaOH = moles of NaOH * molar mass of NaOH
Let's put these calculations into practice using the given values:
Step 1: moles of H2SO4 = (0.0049 g/cm^3) / (98.09 g/mol)
Step 2: Since we have the number of moles of H2SO4, we can directly calculate the number of moles of NaOH using the mole ratio: moles of NaOH = (moles of H2SO4) * 2.
Step 3: Finally, calculate the mass of NaOH by multiplying the moles of NaOH by the molar mass (39.997 g/mol for NaOH): mass of NaOH = (moles of NaOH) * (39.997 g/mol).
By following these steps, you will be able to calculate the mass of NaOH needed to neutralize the given volume of H2SO4 solution.