If there is 1 g KH2PO4 and 1 g K2HPO4 in 100mL of solution, what is the mEq/mL of potassium? The Answer is 0.19mEq/mL. But I need to show work on how to get the answer.
Textbook Applied physical pharmacy By Mansoor M. Amiji, Beverly J. Sandmann
Chapter 3
To find the mEq/mL of potassium in the given solution, we need to calculate the number of milliequivalents (mEq) of potassium present per milliliter of solution.
First, we need to determine the number of moles of each potassium compound in the solution:
1. Calculate the number of moles of KH2PO4:
- The molar mass of KH2PO4 is 136.09 g/mol (1 potassium atom, 2 hydrogen atoms, 1 phosphorus atom, and 4 oxygen atoms).
- Since we have 1 gram of KH2PO4, we divide 1 g by the molar mass to get:
Moles of KH2PO4 = 1 g / 136.09 g/mol = 0.00734 moles
2. Calculate the number of moles of K2HPO4:
- The molar mass of K2HPO4 is 174.18 g/mol (2 potassium atoms, 1 phosphorus atom, and 4 oxygen atoms).
- Since we have 1 gram of K2HPO4, we divide 1 g by the molar mass to get:
Moles of K2HPO4 = 1 g / 174.18 g/mol = 0.00574 moles
Next, we need to calculate the total number of moles of potassium in the solution:
3. Calculate the moles of potassium ions in KH2PO4:
- Each molecule of KH2PO4 contains one potassium ion (K+).
- Therefore, the number of moles of potassium in KH2PO4 is equal to the moles of KH2PO4 calculated in step 1:
Moles of potassium in KH2PO4 = 0.00734 moles
4. Calculate the moles of potassium ions in K2HPO4:
- Each molecule of K2HPO4 contains two potassium ions (2K+).
- Therefore, the number of moles of potassium in K2HPO4 is equal to twice the moles of K2HPO4 calculated in step 2:
Moles of potassium in K2HPO4 = 2 x (0.00574 moles) = 0.01148 moles
Now, we can calculate the total moles of potassium in the solution:
5. Total moles of potassium = Moles of potassium in KH2PO4 + Moles of potassium in K2HPO4
= 0.00734 moles + 0.01148 moles
= 0.01882 moles
Finally, we can calculate the mEq/mL of potassium in the solution:
6. mEq of potassium per milliliter (mEq/mL) = (Total moles of potassium / Volume of solution in liters) x 1000
= (0.01882 moles / 0.1 L) x 1000
= 0.1882 mEq/mL
Therefore, the mEq/mL of potassium in the given solution is 0.1882 mEq/mL, which can be rounded to 0.19 mEq/mL.