Question

what volume of a 1.25 m potassium fluoride (kf) solution would be needed to make 455 ml of a 0.838 m solution by dilution? ? ml of 1.25 m kf be sure to give your answer in the requested units. volume (ml) submit

Explanation:

Step1: Recall dilution formula

The dilution formula is \( M_1V_1 = M_2V_2 \), where \( M_1 \) is the initial molarity, \( V_1 \) is the initial volume, \( M_2 \) is the final molarity, and \( V_2 \) is the final volume.

Step2: Identify known values

We know \( M_1 = 1.25 \, M \), \( M_2 = 0.838 \, M \), and \( V_2 = 455 \, mL \). We need to find \( V_1 \).

Step3: Rearrange formula for \( V_1 \)

Rearranging the dilution formula gives \( V_1=\frac{M_2V_2}{M_1} \).

Step4: Substitute values into formula

Substitute \( M_2 = 0.838 \, M \), \( V_2 = 455 \, mL \), and \( M_1 = 1.25 \, M \) into the formula: \( V_1=\frac{0.838\times455}{1.25} \).
First, calculate the numerator: \( 0.838\times455 = 0.838\times400 + 0.838\times55 = 335.2+46.09 = 381.29 \).
Then, divide by \( 1.25 \): \( V_1=\frac{381.29}{1.25}=305.032 \, mL \).

Answer:

\( 305 \) (rounded to a reasonable number of significant figures, or \( 305.03 \) if more precision is needed)