Question

0.456 L of a 2.5 M KCl solution. Express your answer using two significant figures. What mass of KCl is present in the solution?

Answer 1

To find the mass of KCl in a 0.456 L solution with a molarity of 2.5 M, calculate the moles of KCl and multiply by its molar mass, resulting in 85 g of KCl when rounded to two significant figures.

Step-by-step explanation:

Calculating the Mass of KCl in a Solution

To determine the mass of KCl present in a 0.456 L solution with a molarity of 2.5 M, we first calculate the number of moles of KCl using the formula:

Moles of KCl = Volume of solution (in liters) × Molarity (M)

Moles of KCl = 0.456 L × 2.5 M = 1.14 moles

Next, we use the molar mass of KCl to find the mass. The molar mass of KCl is approximately 74.55 g/mol. So, the mass of KCl is:

Mass of KCl = Moles of KCl × Molar mass of KCl

Mass of KCl = 1.14 moles × 74.55 g/mol

Mass of KCl = 85.087 g

To provide the answer with two significant figures, we round it to 85 g.

Answer 2

To find the mass of KCl, multiply the volume of the solution (0.456 L) by its molarity (2.5 M) to get the moles of KCl, and then multiply by KCl's molar mass (74.55 g/mol) to convert to grams. The mass of KCl is found to be 85.0 grams.

Step-by-step explanation:

To determine the mass of KCl present in 0.456 L of a 2.5 M KCl solution, we need to follow a two-step process:

1. Calculate the number of moles of KCl using the molarity equation: Molarity (M) = moles of solute / liters of solution. We rearrange this formula to solve for moles:

moles of KCl = Molarity (M) × Volume (L)

1. Convert the moles of KCl to grams using the molar mass of KCl. The molar mass of KCl is approximately 74.55 g/mol.

Now, let's calculate:

1. moles of KCl = 2.5 M × 0.456 L = 1.14 moles
2. Mass of KCl = moles × molar mass = 1.14 moles × 74.55 g/mol

Mass of KCl = 85.0 grams (rounded to two significant figures).

Therefore, the mass of KCl present in the 0.456 L solution is 85.0 grams.