Answer:
252 g KOH.
Explanation:
a. First, let's see the formula of molarity:
[tex]Molarit\text{y \lparen M\rparen=}\frac{moles\text{ }of\text{ }solute}{liters\text{ of solution}}=\frac{mol}{L}.[/tex]
Remember that the volume must be in liters. 1 L equals 1000 mL, so the conversion is:
[tex]1500mL\cdot\frac{1\text{ L}}{1000\text{ mL}}=1.5\text{ L.}[/tex]
We want to find the grams of solute, so we can find initially the moles of solute, so let's solve for moles of solute and replace the given data:
[tex]mole\text{s of solute = Molarity}\cdot liters\text{ of solution.}[/tex]
The molarity is 3 M and the volume is 1.5 L:
[tex]\begin{gathered} mol\text{es of solute = 3 M}\cdot1.5\text{ L,} \\ moles\text{ of solute = 4.5 moles.} \end{gathered}[/tex]
Now that we have this value, we can find its mass by using its molar mass. (The molar mass of KOH is 56 g/mol. You can calculate the molar mass of a compound using the periodic table). The conversion would be:
[tex]4.5\text{ moles KOH}\cdot\frac{56\text{ g KOH}}{1\text{ mol KOH}}=252\text{ g KOH.}[/tex]
We require 252 g of KOH.
