help me with some science

Question

If this potassium is put in the drink as potassium chloride (KCl₂), how many moles of potassium chloride is there in 100 g of the drink?

Answer 1

Step 1: Find the molar mass of potassium chloride

For the sake of this question, "molar mass" can be thought of as the number grams that ONE mole of a compound is equal to. This number is given to you on the periodic table for each element. Since potassium chloride is a compound (i.e. composed on multiple atoms bonded together), its molar mass can be found by adding together the individual molar masses of its atoms.

Potassium (K) has a molar mass of 39.01

Chloride (Cl) has a molar mass of 35.45. Since there are two chloride atoms in this molecule though, we need to take that into account by multiplying this number by 2 to get 70.9.

Adding these numbers together gets us the total molar mass of the compound. Again, this number is equal to the number of grams in ONE mole of KCl₂

39.01 + 70.9 = 109.91 g

Step 2: Write down what you are given (100 g potassium chloride) and put it over 1

100 g KCl₂/1

Step 3: Use the molar mass of potassium chloride as a conversion factor to convert from grams of potassium chloride to moles of potassium chloride (i.e. multiply the fractions)

(100 g KCl₂/1) * (1 mol KCl₂/109.91 g KCl₂) = 0.91 mol KCl₂