Sorry, the 1st part to those 2 questions are:
Hard water contains metal ions, most commonly calcium and magnesium ions. Some moderately hard water is found to contain 200ppm of calcium hydrogen carbonate.
See my response at the original question.
No problem! Let's tackle the first question:
First, we need to determine the concentration of calcium ions in the water sample. Given that the water contains 200 ppm (parts per million) of calcium hydrogen carbonate, we need to calculate the amount of calcium ions present.
Calcium hydrogen carbonate (Ca(HCO3)2) dissociates in water to form ions:
Ca(HCO3)2 -> Ca2+ + 2HCO3-
From the equation, we can see that each molecule of calcium hydrogen carbonate produces one calcium ion (Ca2+). Therefore, the concentration of calcium ions in the water sample is also 200 ppm.
Now, let's move on to the second part of your question.