calculate the normality of Ca(OH)2 in a solution made by dissolving 4.75 g Ca(OH)2 in enough water to a make 250 mL of solution
0.512N
To calculate the normality (N) of Ca(OH)2 in a solution, we need to know the molar mass of Ca(OH)2 and the number of equivalents of Ca(OH)2.
Step 1: Calculate the molar mass of Ca(OH)2.
The molar mass of Ca is 40.08 g/mol, the molar mass of O is 16.00 g/mol, and the molar mass of H is 1.01 g/mol. To calculate the molar mass of Ca(OH)2, we multiply the molar mass of each element by the respective number of atoms and sum them up:
Molar mass of Ca(OH)2 = (40.08 g/mol × 1) + (16.00 g/mol × 2) + (1.01 g/mol × 2)
= 40.08 g/mol + 32.00 g/mol + 2.02 g/mol
= 74.10 g/mol
Step 2: Convert grams of Ca(OH)2 to moles.
We are given that 4.75 g of Ca(OH)2 is dissolved in water. To convert grams to moles, we use the formula:
Number of moles = Mass (g) / Molar mass (g/mol)
Number of moles = 4.75 g / 74.10 g/mol
= 0.064 moles
Step 3: Calculate the number of equivalents.
Since each mole of Ca(OH)2 has two equivalents of OH-, we multiply the number of moles by 2:
Number of equivalents = Number of moles × 2
= 0.064 moles × 2
= 0.128 equivalents
Step 4: Calculate the normality.
Normality (N) is defined as the number of equivalents of a solute per liter of solution. In this case, we have 250 mL of solution, which is equivalent to 0.25 L. Thus, we divide the number of equivalents by the volume in liters:
Normality (N) = Number of equivalents / Volume of solution (in liters)
= 0.128 equivalents / 0.25 L
= 0.512 N
Therefore, the normality of Ca(OH)2 in the solution is 0.512 N.
Normality = # equilvalents/L of solution.
#equivalents = grams/equivalent weight.
equivalent weight Ca(OH)2 = molar mass/2
# equivalents = 4.75/equivalent weight = ??
N = ??equivalents/0.250 L = xx