Question

How many grams of potassium bromide, KBr, are in 100.0 mL of a 0.50 M solution?

a) 5 g
b) 50 g
c) 0.5 g
d) 500 g

Answer 1

To calculate the grams of KBr in 100.0 mL of a 0.50 M solution, convert the volume to liters, calculate the number of moles based on the molarity, and then use the molar mass of KBr to find grams. The solution contains approximately 5.95 g of KBr, closest to option (a) 5 g.

Step-by-step explanation:

To calculate the number of grams of potassium bromide (KBr) in a 100.0 mL of a 0.50 M solution, we first need to convert the liters of solution to moles of solute, and then convert moles of solute to grams of the solute using the molar mass of KBr.

• Convert volume from mL to L: 100.0 mL = 0.1000 L
• Calculate moles of KBr using molarity: 0.50 moles/L × 0.1000 L = 0.0500 moles
• Find the molar mass of KBr (K = 39.10 g/mol, Br = 79.90 g/mol): 39.10 g/mol + 79.90 g/mol = 119.00 g/mol
• Convert moles to grams: 0.0500 moles × 119.00 g/mol = 5.95 g of KBr

Therefore, the solution contains 5.95 g of potassium bromide, which closest to option (a) 5 g.