a sample of seawater has a density of 1.02kg/L and has the following ion in parts per million by mass, 19,000 Cl-. how do you find the molar concentration of the ion?
19,000 ppm by mass means
19,000 g Cl^-/1,000,000 g solution.
The solution then consists of 19,000 g Cl^- and 981,000 g H2O.
Remember that molarity = moles/L.
How many moles do you have.
19,000 g Cl^-/atomic mass Cl^- = moles.
What is the volume of water? That is
mass = volume x density. You have density and mass, calculate volume, convert to liters and use in the moles/L formula.
Thank You Dr. Bob, I really appreciate your help
To find the molar concentration of an ion in a solution, you need to use the concept of moles and the formula:
Molar Concentration = (Number of Moles of the Ion) / (Volume of Solution in Liters)
In this case, you are given the density of the seawater, which is 1.02 kg/L. However, you need the volume of the solution in liters, not the density. To convert the density into volume, you will divide the mass of the seawater by its density.
Let's calculate the volume of the seawater sample:
Density = Mass / Volume
Rearranging the formula, you get:
Volume = Mass / Density
Given that the density is 1.02 kg/L, if you have the mass of the seawater sample, you can divide it by the density to get the volume in liters.
Once you know the volume of the seawater sample, you can calculate the number of moles using the formula:
Number of Moles = (Mass of Ion) / (Molar Mass of Ion)
In this case, you are given the concentration of Cl- ions in parts per million (ppm) by mass, which indicates that for every 1 million parts of seawater, 19,000 parts are Cl- ions.
Since the molar mass of Cl- is 35.45 g/mol, you can calculate the mass of Cl- ions present in the seawater sample by dividing the concentration by 1 million and multiplying by the mass of the seawater sample.
Finally, to find the molar concentration of the Cl- ions, divide the number of moles of Cl- ions by the volume of the seawater sample.
Keep in mind that parts per million (ppm) is a mass-to-mass ratio, and the concentration unit for molar concentration is moles per liter (mol/L). So, you will need to convert from ppm to moles before calculating the molar concentration.
Let me know if you need further clarification or any specific calculations.