a 7.50 by mass aqueous ammonia, NH3,solution has a density of 0.973 g/mol. Calculate molality and molarity? Need your ASAP please :(
7.50 what? percent? Is that 7.50% by mass NH3 solution.
Also, is that a density of 0.973 g/mL; surely not 0.970 g/mol. If so, per mols of what?
To calculate the molality and molarity of an aqueous ammonia solution, we need to use the given information: mass and density.
1. Determine the mass of the solution:
- The given solution has a mass of 7.50 g.
2. Determine the volume of the solution:
- We can use the density to calculate the volume since density = mass/volume.
- Rearranging the formula, volume = mass/density.
- Substituting the values: volume = 7.50 g / 0.973 g/mL.
Now, let's calculate the molality and molarity.
Molality (m):
Molality is defined as the number of moles of solute per kilogram of solvent.
3. Determine the number of moles of ammonia (NH3):
- To do this, we need the molar mass of NH3, which is calculated as follows:
- The atomic mass of nitrogen (N) is 14.01 g/mol, and hydrogen (H) is 1.01 g/mol.
- The molar mass of NH3 = (14.01 g/mol) + 3 × (1.01 g/mol) = 17.04 g/mol.
- Now we can convert the mass of NH3 to moles:
- Moles of NH3 = mass of NH3 (g) / molar mass of NH3 (g/mol).
4. Determine the mass of the solvent (water):
- Since the solution is aqueous (meaning water is the solvent), the total mass of the solution is equal to the mass of the solute (NH3) plus the mass of the solvent (water).
- Mass of water = mass of solution (g) - mass of NH3 (g).
5. Calculate the molality:
- Molality (m) = moles of NH3 / mass of water (kg).
- Convert the mass of water to kg.
Molarity (M):
Molarity is defined as the number of moles of solute per liter of solution.
6. Convert the volume of the solution to liters:
- Volume of solution (L) = volume of solution (mL) / 1000.
7. Calculate the molarity:
- Molarity (M) = moles of NH3 / volume of solution (L).
Now, you can apply these steps to calculate the molality and molarity using the given data.