Question

What is the percent potassium, chromium, and oxygen in K2Cr2O7?

Answer 1

Answer:

K2Cr2O7 is 26.58%K, 35.35%Cr AND 38.07% O by mass.  

Explanation:

The formula of percent composition is

          % by mass = mass of component / mass of sample *100%

we have to find the mass of K, Cr, and O in a given mass of a compound .

Mass of K = 2 × 39.10 g = 78.20 g

Mass of Cr = 2 × 52.00 g = 104.00 g

Mass of O = 7 × 16.00 g = 112.00 g

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Mass of K2Cr2O7           = 294.20 g

∴ % K = mass of K /mass of K2Cr2O7 *100%      

  =78.20 g / 294.20 g *100%    =26.58%

% Cr = mass of Cr/ mass of K2Cr2O7 *100%      =104.00 g/294.20 g *100%                            

=35.35%

% O = mass of O / mass of K2Cr2O7 *100%  =112.00 g/294.20 g *100%

       = 38.07 %