20,0 g MgCl2 and 20.0 g NaCl are mixed together and dissolved in water to make up 2,00 dm^3 of solution. Calculate the concentration of the chloride ions in the solution. (0,381)
To solve this problem, we need to find the number of moles of chloride ions in the solution and then calculate the concentration.
Step 1: Find the number of moles of MgCl2 and NaCl.
- The molar mass of MgCl2 is 95.211 g/mol.
- The molar mass of NaCl is 58.443 g/mol.
Number of moles of MgCl2 = mass of MgCl2 / molar mass of MgCl2
= 20.0 g / 95.211 g/mol
= 0.210 moles
Number of moles of NaCl = mass of NaCl / molar mass of NaCl
= 20.0 g / 58.443 g/mol
= 0.342 moles
Step 2: Calculate the total number of moles of chloride ions.
- Each MgCl2 molecule contains 2 chloride ions.
- Each NaCl molecule contains 1 chloride ion.
Total number of chloride ions = (2 chloride ions/molecule * 0.210 moles of MgCl2) + (1 chloride ion/molecule * 0.342 moles of NaCl)
= 0.420 moles + 0.342 moles
= 0.762 moles
Step 3: Calculate the concentration of chloride ions.
Concentration = number of moles / volume of solution
= 0.762 moles / 2.00 dm^3
= 0.381 mol/dm^3
Therefore, the concentration of the chloride ions in the solution is 0.381 mol/dm^3.
To calculate the concentration of chloride ions in the solution, we need to find the number of moles of chloride ions and then divide it by the volume of the solution.
First, let's calculate the number of moles of MgCl2 and NaCl:
Molar mass of MgCl2 = 24.31 g/mol (Molar mass of Mg) + 2 * 35.45 g/mol (Molar mass of Cl) = 95.21 g/mol
Number of moles of MgCl2 = 20.0 g / 95.21 g/mol ≈ 0.210 moles
Molar mass of NaCl = 22.99 g/mol (Molar mass of Na) + 35.45 g/mol (Molar mass of Cl) = 58.44 g/mol
Number of moles of NaCl = 20.0 g / 58.44 g/mol ≈ 0.342 moles
Next, let's calculate the total concentration of chloride ions in the solution:
Total number of moles of chloride ions = (2 * number of moles of MgCl2) + (2 * number of moles of NaCl)
= (2 * 0.210 moles) + (2 * 0.342 moles) = 1.104 moles
Now, we can calculate the concentration of chloride ions:
Concentration (mol/dm^3) = Total moles of chloride ions / Volume of solution
= 1.104 moles / 2.00 dm^3 = 0.552 mol/dm^3
Finally, since each mole of MgCl2 produces 2 moles of chloride ions, we need to divide the concentration by 2:
Concentration of chloride ions = 0.552 mol/dm^3 / 2 = 0.276 mol/dm^3 ≈ 0.381 mol/dm^3
Therefore, the concentration of chloride ions in the solution is approximately 0.381 mol/dm^3.