Calculate the [H3O+] when 1.65 grams of KOH are dissolved in 500.0 mL of solution
moles KOH = grams/molar mass.
solve for moles.
(KOH) = moles/L
solve for (KOH) = ?? molar.
That will be the OH^-.
(H^+)(OH^-) = 1 x 10^-14
solve for (H^+).
To calculate the [H3O+] concentration when 1.65 grams of KOH (potassium hydroxide) is dissolved in 500.0 mL of solution, we need to follow a step-by-step process. Here's how you can do it:
Step 1: Start with the given mass of KOH (1.65 grams).
Step 2: Convert the mass of KOH to moles. To do this, you need the molar mass of KOH, which is calculated by adding the atomic masses of potassium (K), oxygen (O), and hydrogen (H). The atomic masses are:
- Potassium (K) = 39.10 g/mol
- Oxygen (O) = 16.00 g/mol
- Hydrogen (H) = 1.01 g/mol
The molar mass of KOH is therefore:
39.10 g/mol (K) + 16.00 g/mol (O) + 1.01 g/mol (H) = 56.11 g/mol (KOH)
Now, divide the given mass of KOH (1.65 grams) by the molar mass (56.11 g/mol) to obtain the number of moles of KOH.
Step 3: Calculate the volume of the solution in liters. The given volume is 500.0 mL, so we need to convert it to liters. Remember, there are 1000 milliliters in a liter, so divide the given volume by 1000.
500.0 mL ÷ 1000 = 0.500 L
Step 4: Use the balanced chemical equation to determine the number of moles of H3O+ formed when 1 mole of KOH is dissolved in water. The balanced equation for the reaction of KOH with water is:
KOH + H2O → K+ + OH-
From this equation, we can see that for every mole of KOH, one mole of OH- ions is formed. Since H3O+ is the conjugate acid of water, for every mole of OH- formed, one mole of H3O+ ions is also formed.
Step 5: Calculate the mole ratio between KOH and H3O+. This is achieved by multiplying the number of moles of KOH (obtained in step 2) by the mole ratio from the balanced equation in step 4.
Step 6: Finally, divide the moles of H3O+ by the volume of the solution in liters (obtained in step 3) to find the concentration of [H3O+].
Keep in mind that the concentration is expressed in moles per liter (mol/L) or molarity (M).
Following these steps will provide you with the value of [H3O+] when 1.65 grams of KOH is dissolved in 500.0 mL of solution.