To calculate the mass of KOH needed to make a 5 M solution in 185.5 mL, we need to use the formula:
mass = moles × molar mass
where moles is the amount of KOH in moles and molar mass is the mass of one mole of KOH.
We can calculate the moles of KOH as follows:
moles = Molarity × Volume (in liters)
First, we need to convert the volume from milliliters to liters:
185.5 mL = 0.1855 L
Now we can calculate the moles of KOH:
moles = 5 M × 0.1855 L = 0.9275 moles
The molar mass of KOH is 56.11 g/mol. Therefore, the mass of KOH needed is:
mass = 0.9275 moles × 56.11 g/mol = 52.05 g
Therefore, 52.05 grams of KOH are needed to make a 5 M solution in 185.5 mL.