Question

A chemist adds .25L of a .11M potassium dichromate solution to a reaction flask. Calculate the mass in grams of potassium dichromate the chemist has added to the flask. Round your answer to significant digits.

Answer 1

Answer:

The mass of potassium dichromate is 8.1 grams

Explanation:

Step 1: Data given

Volume of potassium dichromate solution = 0.25L

Molarity = 0.11M

Molar mass of potassium dichromate = 294.185 g/mol

Step 2: Calculate moles K2Cr2O7

Moles K2Cr2O7 = molarity * volume

Moles K2Cr2O7 = 0.11M * 0.25L

Moles K2Cr2O7 = 0.0275 moles

Step 3: Calculate mass K2Cr2O7

Mass K2Cr2O7 = moles K2Cr2O7 * molar mass K2Cr2O7

Mass K2Cr2O7 = 0.0275 moles * 294.185 g/mol

Mass K2Cr2O7 = 8.1 grams

The mass of potassium dichromate is 8.1 grams

Answer 2

Answer: 8.2 grams of potassium dichromate the chemist has been added to the flask.

Explanation:

Molarity is defined as the number of moles of solute dissolved per liter of the solution.

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$     .....(1)

Molarity of potassium dichromate solution = 0.11 M

Volume of solution = 0.25 L

Putting values in equation 1, we get:

$0.11M=\frac{\text{Moles of potassium dichromate}}{0.25L}\\\\{\text{Moles of potassium dichromate}}={0.11mol/L\times 0.25L}=0.028mol$

Mass of potassium dichromate =$moles\times {\text {molar mass}}=0.028mol\times 294g/mol=8.2g$

Thus mass in grams of potassium dichromate the chemist has added to the flask is 8.2.