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E) Mn(SO04) 21) A 25.0g piece of iron is placed in a water-filled calorimeter co

ID: 696686 • Letter: E

Question

E) Mn(SO04) 21) A 25.0g piece of iron is placed in a water-filled calorimeter containing 25.0ml of water at 2 8K The water/iron temperature is then measured and found to stabilize at 306k. Assuming that heat is transferred completely between the iron and the water, what was the imitial heat oft specific heat capacity of iron-0.449J/g*K and water 4.18J/g K A) 318K B) 381K C) 231K D) 299K E) 74K 22) What is the mass of AgCI formed from the reaction of 75.0mL of 0 078M AgC HO, solution wit 55.0mL of 0.109M MgCl, solution? A) 0.859g

Explanation / Answer

Answer

B) 381K

Explanation

Heat absorbed by water(qw) = - Heat released by iron(qi)

qw = mass of water × temperatutre raise of wter × Heat capacity of water

   = 25g × 8K × 4.184J/g K

   = 836.8J

qi = mass of iron × T × Heat capacity of iron

= 25g × T × 0.449J/gK

= 11.225J/K× T

qw = qi

836.8J = -11.225J/K × T

   T =- 74.5K

T = 306K - initial temperature

306K - initial temperature = -74.5K

   Initial temperature = 381K