Seawater contains 0.412 g Ca per kilogram of water. What is the number of moles of Ca per kilogram of water? What is the concentration of Ca measured in ppm?
For the first question, it's changing the grams of Ca to moles of Ca. Is it .412 g / 39 g = .0105 moles.
For the second question, I know the seawater formula is NaCl + H2O = 76g. So is it 76g/0.412 g (10^6).
For the first question, you are correct in your approach. To find the number of moles of Ca per kilogram of water, you need to convert the mass of Ca in grams to moles.
Given that there are 0.412 grams of Ca per kilogram of water, you can use the molar mass of Ca, which is approximately 39 grams per mole, to convert grams to moles:
0.412 g Ca / 39 g/mol = 0.01056 mol Ca
So, there are approximately 0.01056 moles of Ca per kilogram of water.
For the second question, the concentration of Ca can be expressed in parts per million (ppm). To calculate this, you need to divide the mass of Ca by the mass of the seawater solution and then multiply the result by one million.
Since the seawater formula is NaCl + H2O = 76g, it means that 1 kilogram of seawater has a mass of 76 grams.
To find the concentration of Ca in ppm, you can use the following calculation:
(0.412 g Ca / 76 g seawater) * 10^6 = 5,421 ppm (rounded to the nearest whole number)
So, the concentration of Ca in the seawater sample is approximately 5,421 parts per million.