If the density of ocean water at a depth of 1.00 x 10^4 m is 1.071 g/mL and if 27.0 g of water at that depth contains 197 mg of potassium chloride, what is the molarity of potassium chloride in the sample?
M = mols/L
How many mols KCl are there? mols = grams/molar mass = ?
How2 many L are there? That's mass H2O = volume H2O x density H2O. Solve for volume in mL and convert to L.
To find the molarity of potassium chloride in the sample, we need to calculate the number of moles of potassium chloride and the volume of the solution.
Molarity (M) is defined as moles of solute per liter of solution.
First, let's calculate the number of moles of potassium chloride:
Given that the sample contains 27.0 g of water at a depth of 1.00 x 10^4 m and 197 mg of potassium chloride, we can find the mass of potassium chloride in the sample.
1 g = 1000 mg (converting grams to milligrams)
197 mg = 197/1000 g = 0.197 g
Next, we need to determine the number of moles of potassium chloride. To do this, we will use the molar mass of potassium chloride.
The molar mass of potassium chloride (KCl) is the sum of the atomic masses of potassium (K) and chlorine (Cl):
Molar mass of KCl = atomic mass of K + atomic mass of Cl
From the periodic table, we find:
Atomic mass of K = 39.10 g/mol
Atomic mass of Cl = 35.45 g/mol
Molar mass of KCl = 39.10 g/mol + 35.45 g/mol = 74.55 g/mol
Now we can calculate the number of moles of potassium chloride:
Number of moles of KCl = mass of KCl / molar mass of KCl
Number of moles of KCl = 0.197 g / 74.55 g/mol
Now let's calculate the volume of the solution:
Given that the density of ocean water at a depth of 1.00 x 10^4 m is 1.071 g/mL, we can determine the volume of the sample.
Density = mass / volume
Volume = mass / density
Volume = 27.0 g / 1.071 g/mL
Volume = 25.215 mL
Finally, convert the volume from milliliters (mL) to liters (L):
Volume = 25.215 mL * (1 L / 1000 mL)
Volume = 0.025215 L
Now we can calculate the molarity of potassium chloride:
Molarity (M) = moles of solute / volume of solution
Molarity (M) = (0.197 g / 74.55 g/mol) / 0.025215 L
Calculating this value will give us the molarity of potassium chloride in the sample.