Question

A solution is made by dissolving 48.5g of potassium iodide (KI) in 250cm³ of water. Calculate the concentration of KI in mole/liter.

a) 0.5 mol/L
b) 1.0 mol/L
c) 2.0 mol/L
d) 0.2 mol/L

Answer 1

To find the concentration of KI, we calculate the moles of KI and then divide by the volume in liters. After calculations, we find that the concentration is approximately 1.0 mol/L, with the closest answer choice being option b) 1.0 mol/L.

Step-by-step explanation:

To calculate the concentration of potassium iodide (KI) in moles per liter, we need to use the formula:

Concentration (M) = Moles of solute / Volume of solution in liters

First, we find the moles of KI. We can do this by dividing the mass of the solute (48.5g) by its molar mass. The molar mass of KI (39.10 g/mol for K + 126.90 g/mol for I) is 166.00 g/mol.

Moles of KI = mass (g) / molar mass (g/mol) = 48.5g / 166.00g/mol = 0.292 moles

Now we need to convert the volume from cm³ to liters. Since there are 1000 cm³ in 1 liter, we have:

Volume in liters = 250 cm³ / 1000 = 0.250 L

Finally, we calculate the concentration:

Concentration (M) = 0.292 moles / 0.250 L = 1.168 mol/L

Since none of the options exactly match, the closest option to our calculated value is:

b) 1.0 mol/L (by rounding to one significant figure)