Question

What is the mass, in grams, of potassium in 12.5 g of K2Cr2O7 (molar mass = 294 g/mol)? (K = 39, O = 16, Cr = 52)

a) 1.66 g
b) 0.0424 g
c) 8.80 g
d) 3.32 g

Answer 1

Option d)3.32 g is correct.

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Answer 2

Answer:

option D is the correct one

Explanation:

Let us first write the formula for finding the overall percentage of K in K2Cr207

The molar mass of the compound is= 294

Percentage of K in compound would be

= 39 x 2 / 294 x 100 = 26.53%

So if we are now given 12.5 grams of the compound then, using the same principle we see that

K = 26.53/100 x 12.5

K = 3.316 grams

Rounding it off

K = 3.32 g

Hence among the fout options given, option D is the correct one