How many grams of potassium are there in a 100 g sample of KI, potassium iodide?

Answer 1

We can look at this problem using mass percent. First, lets find the molar mass of KI: 39.1 g (K) + 126.9 g (I) = 166.0 g KI.

Now we want to find the amount of K in KI, which can be solved by calculating K molar mass / KI molar mass, which means 39.1 g K / 166.0 g KI. We get 23.55%. In one mole or 166 g of KI, 23.55% of it is K. Therefore, in 100 grams of KI , 23.55% of it would be K, so 23.55 g of potassium are in 100 g sample of KI.

Another way to do it is setting up a proportion. (39.1 g K / 166 g KI) = (x grams of K / 100 g KI). Cross multiply and solve for x, which equals 23.55 grams K. Hope that helped!