20 g of K3PO4 dissolved in 350 ml water,to come up with 500 ml solution.
calculate :
molecular weight
Equivalent weight
molarity
normality
molality
And you know how to do which ones? What do you not understand. The definitions is where you start.
How Ican calculate equivalent weight
How Ican convert 500 ml to 500 kg to use it in molality
thank you
To calculate the molecular weight (MW) of K3PO4, we need to add up the atomic weights of each element:
Molecular weight of K3PO4:
(3 x Atomic weight of potassium) + (1 x Atomic weight of phosphorus) + (4 x Atomic weight of oxygen)
Using atomic weights from the periodic table:
Atomic weight of potassium (K) = 39.10 g/mol
Atomic weight of phosphorus (P) = 30.97 g/mol
Atomic weight of oxygen (O) = 16.00 g/mol
MW of K3PO4:
(3 x 39.10 g/mol) + 30.97 g/mol + (4 x 16.00 g/mol) = 212.27 g/mol
To calculate the equivalent weight (EW), we divide the molecular weight by the number of replaceable H or OH ions in the compound. For K3PO4, there are 3 potassium ions (K+) and 1 phosphate ion (PO4³-). So the equivalent weight is:
EW of K3PO4 = MW of K3PO4 / (3 x charge of K ion + charge of PO4 ion)
EW of K3PO4 = 212.27 g/mol / (3 x 1 + 3 x 4) = 212.27 g/mol / 15 = 14.15 g/mol
To calculate the molarity (M), we need to know the number of moles of solute (K3PO4) and the volume of the solution (500 ml).
Molarity (M) = moles of solute / volume of solution (in liters)
First, let's calculate the moles of K3PO4:
moles of K3PO4 = mass of K3PO4 / MW of K3PO4
mass of K3PO4 = 20 g
MW of K3PO4 = 212.27 g/mol
moles of K3PO4 = 20 g / 212.27 g/mol = 0.094 mol
Now, let's convert the volume of the solution to liters:
500 ml = 500 / 1000 = 0.5 L
Molarity (M) = 0.094 mol / 0.5 L = 0.188 M
To calculate the normality (N), we multiply the molarity by the number of equivalents per mole of solute. For K3PO4, the number of equivalents is 3 (derived from the 3 K ions). So:
Normality (N) = molarity (M) x number of equivalents
Normality (N) = 0.188 M x 3 = 0.564 N
To calculate the molality (m), we need to know the mass of the solvent (water) and the number of moles of solute (K3PO4).
Molality (m) = moles of solute / mass of solvent (in kg)
First, let's calculate the mass of water in kg:
mass of water = volume of water x density of water
volume of water = 350 ml = 350 / 1000 = 0.35 L
density of water = 1 g/ml = 1 g/cm³ = 1000 kg/m³
mass of water = 0.35 L x 1000 kg/m³ = 0.35 kg
Molality (m) = 0.094 mol / 0.35 kg = 0.268 mol/kg
To calculate the molecular weight, equivalent weight, molarity, normality, and molality of the given solution, K3PO4 (potassium phosphate), we need to follow a systematic approach:
1. Molecular Weight:
The molecular weight can be calculated by summing up the atomic masses of all the atoms in the formula unit.
The atomic masses of the elements involved are:
K (Potassium) = 39.10 g/mol
P (Phosphorus) = 30.97 g/mol
O (Oxygen) = 16.00 g/mol
Since there are three potassium ions (K) and one phosphate ion (PO4), the molecular weight of K3PO4 is calculated as:
Molecular weight = (3 × atomic mass of K) + (1 × atomic mass of P) + (4 × atomic mass of O)
Therefore, Molecular weight = (3 × 39.10 g/mol) + (1 × 30.97 g/mol) + (4 × 16.00 g/mol)
= 94.20 + 30.97 + 64.00
= 189.17 g/mol
2. Equivalent Weight:
For ionic compounds like K3PO4, the equivalent weight is determined by the number of ions or protons produced per formula unit.
Since K3PO4 dissociates into three potassium ions (K+) and one phosphate ion (PO4^3-), the equivalent weight is equal to its molecular weight divided by the number of positive/negative charges per formula unit.
Therefore, Equivalent weight = Molecular weight / number of charges
= 189.17 g/mol / (3+1)
= 189.17 g/mol / 4
= 47.29 g/mol
3. Molarity:
Molarity refers to the number of moles of a solute in one liter of the solution.
To calculate the molarity of K3PO4, we need to determine the number of moles of solute (K3PO4) and the volume of the solution (in liters).
Number of moles of K3PO4 = mass of K3PO4 / molar weight of K3PO4
The given mass of K3PO4 = 20 g
Number of moles of K3PO4 = 20 g / 189.17 g/mol
≈ 0.1057 mol
Volume of the solution = 500 ml = 500 / 1000 L
= 0.5 L
Molarity = Number of moles / Volume in liters
= 0.1057 mol / 0.5 L
= 0.2114 M
4. Normality:
Normality is a measure of the concentration of reactive species (equivalent of solute) in a solution.
Normality can be calculated by multiplying the molarity by the number of equivalents per mole of solute. Since K3PO4 has only one equivalent of reactive species per mole, the normality is the same as the molarity.
Therefore, Normality = Molarity = 0.2114 N
5. Molality:
Molality represents the number of moles of solute per kilogram of solvent.
To calculate the molality, we need to convert the volume of water (in ml) to its mass (in grams) using the density of water, assuming it is 1 g/ml.
The given volume of water = 350 ml
Mass of water = volume of water x density of water
= 350 g
Molality = Number of moles of solute / Mass of solvent in kg
= 0.1057 mol / 0.350 kg
= 0.302 M
In summary:
Molecular weight of K3PO4 = 189.17 g/mol
Equivalent weight of K3PO4 = 47.29 g/mol
Molarity of K3PO4 = 0.2114 M
Normality of K3PO4 = 0.2114 N
Molality of K3PO4 = 0.302 M