molar mass :
H₂O = 18.0 g/mol
C₄H₁₀ = 58.0 g/mol
2 C₄H₁₀(g)+ 13 O₂(g) →10 H₂O(g)+ 8 CO₂(g)
2 x ( 58.0) g -------------- 10 x ( 18.0 ) g
2.15 g -------------------- mass of water
mass of water = 2.15 x 10 x 18.0 / 2 x 58.0
mass of water = 387 / 116
mass of water = 3.336 g
hope this helps!
