Calculate the number of grams of h2c2o4.2h2o needed to prepare exactly 250mL of a 0.200 N solution of the acid?
How many equivalents do you need?
# equivalents = N x L = ?
Then #eq = grams/equv weight
Solve for grams.
3.5
To calculate the number of grams of H2C2O4·2H2O needed to prepare the desired solution, we need to use the formula:
moles = volume (in liters) × molarity
First, let's convert the given volume from milliliters (mL) to liters (L):
Volume = 250 mL ÷ 1000 mL/L = 0.250 L
Now, we can proceed to calculate the moles of H2C2O4·2H2O needed to prepare the solution:
moles = 0.250 L × 0.200 (N)
Here, N represents normality, which is a measure of concentration. However, the units for normality are not moles per liter (M), so we need to convert it to moles to be able to make use of the formula.
To convert normality (N) to molarity (M), we need to know the balanced equation for the acid and its equivalents. Assuming H2C2O4 is a diprotic acid, it will have two equivalents (eq) per mole.
So, to convert normality to molarity, we divide the normality by the number of equivalents:
Molarity (M) = Normality (N) ÷ Number of equivalents
Now, let's substitute the given normality into the formula:
Molarity = 0.200 N ÷ 2 eq = 0.100 M
Now, we can calculate the moles using the equation:
moles = 0.250 L × 0.100 M
Once we have the moles of H2C2O4·2H2O, we need to convert it to grams using its molar mass. The molar mass of H2C2O4·2H2O can be calculated by summing the atomic masses of its constituent elements:
H2: 2 g/mol × 2 = 4 g/mol
C2: 12 g/mol × 2 = 24 g/mol
O4: 16 g/mol × 4 = 64 g/mol
2H2O: 18 g/mol × 2 = 36 g/mol
Adding up these masses, we get:
Molar mass of H2C2O4·2H2O = 4 g/mol + 24 g/mol + 64 g/mol + 36 g/mol = 128 g/mol
Finally, let's perform the calculation:
grams = moles × molar mass
Substituting the values we have:
grams = (0.250 L × 0.100 M) × 128 g/mol
Calculating this expression will give you the number of grams of H2C2O4·2H2O needed to prepare the 0.200 N solution.