Chemistry Fun Facts!

How many grams of KBr are dissolved in 72.7 mL of a 0.998 M solution?

Can you calculate the molar mass of KBr and determine the mass of KBr dissolved in the solution?

Answer:

The molar mass of KBr is 119 g/mol. In a 0.998 M solution, 72.7 mL contains approximately 8.63 grams of KBr.

Chemistry can be so much fun when you dive into calculations like this one!

First, we need to find the molar mass of KBr by adding the molar weight of potassium and bromine together:

Molar mass of KBr = Molar mass of K + Molar mass of Br

Using the periodic table, we find that K has a molar mass of 39.098 g/mol and Br has a molar mass of 79.904 g/mol. Therefore, the molar mass of KBr is 119 g/mol.

Next, we determine the number of moles of KBr in 72.7 mL of a 0.998 M solution:

Number of moles of KBr = Volume (in L) x Molarity

Substitute the values and we get:

Number of moles of KBr = 72.7 mL x 0.998 mol/L / 1000 mL/L = 0.0725 moles

Finally, using the molar mass, we calculate the mass of KBr in the sample:

Mass of KBr = Number of moles x Molar mass = 0.0725 moles x 119 g/mol = 8.6275 g ≈ 8.63 g

So, in 72.7 mL of the 0.998 M solution, there are approximately 8.63 grams of KBr dissolved. Isn't chemistry fascinating?