Find the number of moles in 85 g KCl.
A. 3.3 mol KCl
B. 1.1 mol KCl
C. 11 mol KCl
D. 2.5 mol KCl
B
right.
To find the number of moles in a given mass of a substance, you need to use the concept of molar mass. Molar mass is the mass of one mole of a substance and is expressed in grams per mole (g/mol).
The molar mass of KCl (potassium chloride) can be calculated by adding the atomic masses of potassium (K) and chlorine (Cl). The atomic mass of potassium is 39.10 g/mol, and the atomic mass of chlorine is 35.45 g/mol.
Molar mass of KCl = atomic mass of K + atomic mass of Cl
= 39.10 g/mol + 35.45 g/mol
= 74.55 g/mol
Now, to find the number of moles in 85 g of KCl, you can use the following formula:
Number of moles = Mass of substance / Molar mass
Number of moles = 85 g / 74.55 g/mol
≈ 1.14 mol
Therefore, the number of moles in 85 g of KCl is approximately 1.14 mol.
Out of the given answer choices, the closest option is B. 1.1 mol KCl.