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Please please help!

What is the mass percent of potassium chloride when 9.35 grams of potassium chloride is mixed into 162.98 grams of water? Choose the answer with the appropriate significant figures and choose the correct unit.

Respuesta :

kenmyna

 The mass  percent  of potassium chloride  is   1.386%

calculation

mass  percent = actual mass/ Theoretical mass x 100

Actual mass = 9.35 g

Theoretical mass  is  calculated as below

Step 1 : write the equation for reaction

KCl + H₂O  →   KOH + HCl

Step 2: find the moles of Hâ‚‚O

moles = mass÷ molar mass

The molar mass of H₂O = (2 x1 ) +(16)  = 18 g/mol

moles is therefore = 162.98 g÷ 18 g/mol =9.054 moles

Step 3: use the mole ratio to determine the moles of KCl

KCl: H₂O  is 1:1 therefore the moles of KCl  is also = 9.054 moles

Step 4:  find the  theoretical mass of KCl

mass = moles x molar mass

from periodic table the  molar mass of KCl = 39 +35.5 =74.5 g/mol

mass = 9.054 moles x 74.5 g/mol =674.5 g


Theoretical mass is therefore = 9.35 g/ 674.5 g x 100 = 1.386%


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