Question

What is the molarity of a solution that contains 28g of KOH in 2L of solution?

Answer 1

To find the molarity of a solution with 28g of KOH in 2L, the mass of KOH is first converted into moles and then divided by the volume of the solution in liters, resulting in a molarity of 0.2495 M.

Step-by-step explanation:

The molarity of a solution is a measure of the concentration of solute in a solution. To calculate it, you need to know the amount of solute, in this case, potassium hydroxide (KOH), and the volume of the solution. Given that the mass of KOH is 28g and the volume of the solution is 2L, you first convert the mass of KOH to moles by dividing by its molar mass, which for KOH is approximately 56.11 g/mol. Then, you divide the number of moles by the volume of solution to get the molarity.

Molarity = (Moles of solute) / (Volume of solution in liters)

First, let's calculate the moles of KOH:
Moles of KOH = 28g / 56.11 g/mol = 0.499 moles

Now, we calculate the molarity:

Molarity = 0.499 moles / 2 L = 0.2495 M

Answer 2

You should know hte formula c=n/v (c is the molarity, n is moles and v is volume)

To change from mass to moles we use n=m/M (n is moles, m is mass and M is molar mass)

We can find the M of KOH from the periodic table (K=39g/mol, O=16g/mol, H=1g/mol)
Therefore, M of KOH is 39+16+1=56g/mol

Now lets find n: n=28/56=0.5mol

Finally, the molarity is c=0.5/2=0.25M