Question

suppose of potassium bromide is dissolved in of a aqueous solution of silver nitrate.calculate the final molarity of potassium cation in the solution. you can assume the volume of the solution doesn't change when the potassium bromide is dissolved in it.be sure your answer has the correct number of significant digits.

Answer 1

The final molarity of potassium cation in the solution is 0.125 M.

Step-by-step explanation:

To calculate the final molarity of potassium cation (K+) in the solution, we need to determine the number of moles of potassium bromide (KBr) and silver nitrate (AgNO3) present in the solution. First, we calculate the moles of KBr by dividing the mass of KBr by its molar mass. Then, we use the equation: Moles of KBr = Moles of K+ in the solution. Finally, we divide the moles of K+ by the volume of the solution in liters to calculate the final molarity of potassium cation.

Let's apply this to the given information:

• Mass of KBr = 5.95 g
• Volume of solution = 400 cm³ = 0.4 L
• Molar mass of KBr = 119.0 g/mol

First, calculate the moles of KBr:

Moles of KBr = Mass of KBr / Molar mass of KBr

Moles of KBr = 5.95 g / 119.0 g/mol = 0.05 mol

Since KBr dissociates into K+ and Br- ions in solution in a 1:1 ratio, the moles of potassium cation (K+) in the solution is also 0.05 mol. Then, we can calculate the final molarity of K+:

Molarity of K+ = Moles of K+ / Volume of solution

Molarity of K+ = 0.05 mol / 0.4 L = 0.125 M

Answer 2

The final molarity of potassium cation in the solution is 0.30 M.

here is the solution:

Step 1: Calculate the moles of potassium bromide

moles of KBr = (mass of KBr) / (molar mass of KBr)

moles of KBr = (0.30 g) / (119.0 g/mol)

moles of KBr = 0.00252 mol

Step 2: Calculate the volume of the solution

volume of solution = (moles of KBr) / (molarity of KBr)

volume of solution = (0.00252 mol) / (0.30 M)

volume of solution = 0.0084 L

Step 3: Calculate the final molarity of potassium cation

molarity of K+ = (moles of K+) / (volume of solution)

Since potassium bromide dissociates completely in water to give potassium ions and bromide ions, the number of moles of potassium ions is equal to the number of moles of potassium bromide that were dissolved.

molarity of K+ = (moles of KBr) / (volume of solution)

molarity of K+ = (0.00252 mol) / (0.0084 L)

molarity of K+ = 0.30 M .