The density of ocean water depends on the depth because pressure compresses the water. If the density of ocean water at a depth of 10,000 m is 1.071 g/mL and if 25.0 g of water at that depth contains 190 mg of potassium chloride, what is the molar concentration of potassium chloride in the sample?
To find the molar concentration of potassium chloride in the sample, we need to use the given information about the mass of potassium chloride and the density of ocean water.
First, convert the given mass of potassium chloride from milligrams (mg) to grams (g):
190 mg = 190/1000 g = 0.19 g
Next, we need to find the volume of the water sample that contains the potassium chloride. We can calculate the volume by dividing the mass of water by the density at a depth of 10,000 m (1.071 g/mL).
Volume of water = Mass of water / Density of water
Volume of water = 25.0 g / 1.071 g/mL
Now, we have the volume of water in milliliters (mL). To convert this to liters (L), we divide by 1000:
Volume of water = (25.0 g / 1.071 g/mL) / 1000 = 0.023 liters
Finally, we can find the molar concentration of potassium chloride by dividing the mass of potassium chloride (in grams) by the volume of water (in liters) we calculated earlier:
Molar concentration of potassium chloride = Mass of potassium chloride / Volume of water
Molar concentration of potassium chloride = 0.19 g / 0.023 L
Now, calculate the molar concentration:
Molar concentration of potassium chloride = 8.26 mol/L (rounded to two decimal places)
Therefore, the molar concentration of potassium chloride in the water sample is approximately 8.26 mol/L.