7.5g of potass react with water to produce potass hydroxide and hydro gas.what mass of potass hydroxide produced.  unbalanced: K+H2O, KOH+H2?

Molar mass of K = 39.1 g/mol
Molar mass of KOH = (39.1 + 16.0 + 1.0) = 56.1 g/mol

Equation for the reaction:
2K + 2H₂O → 2KOH + H₂
Mole ratio K : H₂O = 2 : 2 = 1 : 1

Moles of K reacted = (7.5 g) / (39.1 g/mol) = 0.192 mol
Moles of KOH produced = 0.192 mol
Mass of KOH produced = (0.192 mol) × (56.1 g/mol) = 10.8 g

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OR:

(7.5 g K) × (1 mol K / 39.1 g K) × (1 mol KOH / 1 mol K) × (56.1 g KOH / 1 mol KOH)

= 10.8 g KOH

2K + 2H2O --> 2KOH+H2
 
  now convert mass given to moles 

  then  multiply by molar mass  KOH