How many moles are in 128.9 grams of Cr2 (SO3) 2?

Answer: 0.5 moles

Explanation:

Cr2 (SO3) 2 is the chemical formula for chromium sulphate.

Given that,

Amount of moles of Cr2 (SO3) 2 (n) = ?

Mass of Cr2 (SO3) 2 in grams = 128.9g

For molar mass of Cr2 (SO3) 2, use the atomic masses:

Chromium, Cr = 52g;

Sulphur, S = 32g;

Oxygen, O = 16g

Cr2 (SO3) 2 =

(52g x 2) + [ (32g + 16g x 3) x 2]

= 104g + [ (32g + 48g) x 2]

= 104g + [80g x 2]

= 104g + 160g

= 264g/mol

Since, n = mass in grams / molar mass

n = 128.9g / 264g/mol

n = 0.488 mole [Round the value of n to the nearest tenth which is 0.5

Thus, there are 0.5 moles in 128.9 grams of Cr2 (SO3) 2