We're doing a lab report on the hardness of water, and one of the calculations is
"The EDTA reacts with the hard water ions in a 1:1 mole ratio. Calculate the molarity of the ions present in 20 mL of water tested."
How would you do this?
volume and mass
A weather ballon with a 2 meter diameter at ambient temperature holds 525 grams of helium. What type of electronic probe could be used to determine the pressure inside the balloon?
To calculate the molarity of the ions present in 20 mL of water, you need to know the number of moles of the ions present. The key information here is that EDTA reacts in a 1:1 mole ratio with the hard water ions.
To determine the molarity, you first need to find the number of moles of the ions present in the 20 mL of water. Here's a step-by-step process to calculate it:
1. Identify the specific ions you are working with in the hard water. For example, if you are testing for calcium ions (Ca2+) and magnesium ions (Mg2+), you will need to determine the moles of these two ions.
2. Convert the volume of water in milliliters (mL) to liters (L). Since 1 L is equal to 1000 mL, 20 mL of water is equal to 0.02 L.
3. Use the formula:
moles = molarity × volume in liters
Since you are calculating the moles of ions in the 20 mL of water, you need to divide the volume by 1000 to convert it to liters.
Therefore, the formula becomes:
moles = molarity × (volume in mL / 1000)
4. Rearrange the formula to solve for molarity:
molarity = moles / (volume in L)
5. Plug in the known values. For example, if you found that the number of moles of calcium ions is 0.01 mol, and you are working with 20 mL of water, the molarity would be:
molarity = 0.01 mol / 0.02 L
molarity = 0.5 M
Repeat this calculation for each type of ion you are testing. Remember to adjust the molarity calculation based on the specific molar ratio given in the problem statement for each ion.
By following these steps, you can calculate the molarity of the ions present in 20 mL of water tested.