The specific heat of a certain substance is 0 . 86   J   g - 1   K - 1 . Assuming ideal solution behavior, the energy required (in J ) to heat 10   g of 1 molal of its aqueous solution from 300   K to 310   K is closest to : [Given: molar mass of the substance = 58   g   mol - 1 ; specific heat of water = 4 . 2   J   g - 1   K - 1 ]

Step-by-step solution

Specific heat capacity of substance = 0 . 86   J   g - 1   K - 1 1 molal aqueous solution ⇒ 1000   gm water has 58   gm solute (total mass of solution = 1058   gm ) If we take 10   gm solution it would have water = 1000 1058 × 10   gm substance = 58 1058 × 10   gm Heat required = 1000 1058 × 10 × 4 . 2 × 10 (for water) = 396 . 975 58 1058 × 10 × 0 . 86 × 10 (for substance) = 4 . 715 = 396 . 975 + 4 . 715 = 401 . 69 ≃ 40