Question

Need help on my study guide test is in 2 days

Answer 1

252 g KOH.

Step-by-step explanation:

a. First, let's see the formula of molarity:

`Molarit\text{y \lparen M\rparen=}\frac{moles\text{ }of\text{ }solute}{liters\text{ of solution}}=(mol)/(L).`

Remember that the volume must be in liters. 1 L equals 1000 mL, so the conversion is:

`1500mL\cdot\frac{1\text{ L}}{1000\text{ mL}}=1.5\text{ L.}`

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:

`mole\text{s of solute = Molarity}\cdot liters\text{ of solution.}`

The molarity is 3 M and the volume is 1.5 L:

`\begin{gathered} mol\text{es of solute = 3 M}\cdot1.5\text{ L,} \\ moles\text{ of solute = 4.5 moles.} \end{gathered}`

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:

`4.5\text{ moles KOH}\cdot\frac{56\text{ g KOH}}{1\text{ mol KOH}}=252\text{ g KOH.}`

We require 252 g of KOH.