Calculate the molar concentrations for each of the following solutions:
A)1.5g NaCI in 100 ml solution
B)1.5g K2Cr2O7 in 100 ml solution
C)5.55g Na2SO4 in 125 ml solution
D)20g MgBr2 in 250ml solution
To calculate the molar concentration for each solution, we need to know the molar mass of the compound.
The molar mass of NaCl (Sodium Chloride) is 58.44 g/mol.
The molar mass of K2Cr2O7 (Potassium Dichromate) is 294.18 g/mol.
The molar mass of Na2SO4 (Sodium Sulfate) is 142.04 g/mol.
The molar mass of MgBr2 (Magnesium Bromide) is 184.11 g/mol.
Now we can proceed with the calculations:
A) 1.5g NaCl in 100ml solution:
Moles of NaCl = mass/molar mass
Moles of NaCl = 1.5g / 58.44 g/mol ≈ 0.0257 mol
Molar concentration = moles/volume
Molar concentration = 0.0257 mol / 0.1 L = 0.257 M
B) 1.5g K2Cr2O7 in 100ml solution:
Moles of K2Cr2O7 = mass/molar mass
Moles of K2Cr2O7 = 1.5g / 294.18 g/mol ≈ 0.0051 mol
Molar concentration = moles/volume
Molar concentration = 0.0051 mol / 0.1 L = 0.051 M
C) 5.55g Na2SO4 in 125ml solution:
Moles of Na2SO4 = mass/molar mass
Moles of Na2SO4 = 5.55g / 142.04 g/mol ≈ 0.0391 mol
Molar concentration = moles/volume
Molar concentration = 0.0391 mol / 0.125 L = 0.313 M
D) 20g MgBr2 in 250ml solution:
Moles of MgBr2 = mass/molar mass
Moles of MgBr2 = 20g / 184.11 g/mol ≈ 0.1086 mol
Molar concentration = moles/volume
Molar concentration = 0.1086 mol / 0.25 L = 0.434 M
So the molar concentrations for the given solutions are:
A) 0.257 M
B) 0.051 M
C) 0.313 M
D) 0.434 M
To calculate the molar concentrations for each of the given solutions, we need to determine the number of moles of solute and the volume of the solution in liters.
A) For 1.5g NaCl in 100ml solution:
1. Calculate the number of moles of NaCl:
- The molar mass of NaCl is 58.44 g/mol.
- Moles of NaCl = mass of NaCl / molar mass of NaCl = 1.5g / 58.44 g/mol = 0.0257 mol
2. Convert the volume to liters:
- Volume in liters = 100 ml / 1000 ml/L = 0.1 L
3. Calculate the molar concentration:
- Molar concentration (M) = moles of solute / volume of solution in liters
- Molar concentration of NaCl = 0.0257 mol / 0.1 L = 0.257 M
Therefore, the molar concentration of NaCl in the given solution is 0.257 M.
B) For 1.5g K2Cr2O7 in 100ml solution:
1. Calculate the number of moles of K2Cr2O7:
- The molar mass of K2Cr2O7 is 294.19 g/mol.
- Moles of K2Cr2O7 = mass of K2Cr2O7 / molar mass of K2Cr2O7 = 1.5g / 294.19 g/mol = 0.0051 mol
2. Convert the volume to liters:
- Volume in liters = 100 ml / 1000 ml/L = 0.1 L
3. Calculate the molar concentration:
- Molar concentration (M) = moles of solute / volume of solution in liters
- Molar concentration of K2Cr2O7 = 0.0051 mol / 0.1 L = 0.051 M
Therefore, the molar concentration of K2Cr2O7 in the given solution is 0.051 M.
C) For 5.55g Na2SO4 in 125ml solution:
1. Calculate the number of moles of Na2SO4:
- The molar mass of Na2SO4 is 142.04 g/mol.
- Moles of Na2SO4 = mass of Na2SO4 / molar mass of Na2SO4 = 5.55g / 142.04 g/mol = 0.0391 mol
2. Convert the volume to liters:
- Volume in liters = 125 ml / 1000 ml/L = 0.125 L
3. Calculate the molar concentration:
- Molar concentration (M) = moles of solute / volume of solution in liters
- Molar concentration of Na2SO4 = 0.0391 mol / 0.125 L = 0.313 M
Therefore, the molar concentration of Na2SO4 in the given solution is 0.313 M.
D) For 20g MgBr2 in 250ml solution:
1. Calculate the number of moles of MgBr2:
- The molar mass of MgBr2 is 184.11 g/mol.
- Moles of MgBr2 = mass of MgBr2 / molar mass of MgBr2 = 20g / 184.11 g/mol = 0.1085 mol
2. Convert the volume to liters:
- Volume in liters = 250 ml / 1000 ml/L = 0.25 L
3. Calculate the molar concentration:
- Molar concentration (M) = moles of solute / volume of solution in liters
- Molar concentration of MgBr2 = 0.1085 mol / 0.25 L = 0.434 M
Therefore, the molar concentration of MgBr2 in the given solution is 0.434 M.