Respuesta :

kenmyna

The mass  of potassium that  must react  with water to  produce   50.0  grams of H2  is    1950 grams


calculation

Step 1 :  write  the equation for reaction


 2 K  + 2H2O →  2KOH  + H2

  step 2: find the  moles of H2 that is formed

moles  = mass/ molar mass

from periodic table  the  molar  mass of H2 = 2  g/mol

=  50.0 g/2 = 25 moles

Step  3:  use the mole  ratio  to calculate the moles of K

 the mole  ratio  of K :H2 is 2:1

therefore the  moles of K =  25  moles x2/1 = 50  moles

Step 4:  find the mass of K

mass =moles x  molar  mass

from periodic table the molar mass of K  = 39 g/mol

mass=  50 moles x 39 g/mol = 1950 grams

mathjohndough

The reaction between water and a metal is vigorous and  produces a metal hydroxide and hydrogen gas. First we write a balanced equation for the reaction.

[tex]2K + 2H_2O \implies 2KOH + H_2[/tex]

First we find the number of moles of [tex]H_2[/tex] using the 50 g mass and the molar mass of dihydrogen 2.01grams.

[tex]50 g H_2 \times \frac{1 mol H_2}{ 2.01 g} = 24.88\ mol H_2[/tex]

Then we use the moles of hydrogen and molar mass of K, 39.01 to find the mass of potassium needed to react.[tex]24.88 mol H_2 \times \frac{2 mol K}{1mol H_2} \times \frac{ 39.01g}{ mol} = 1941.14 g K[/tex]

1941.14 g potassium should react with water.

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