You mix 100. mL of 1.0 M HCI with 100 mL of 1.0 NaOH, both at 25 °C. The tempera

Question

You mix 100. mL of 1.0 M HCI with 100 mL of 1.0 NaOH, both at 25 °C. The temperature of yo calorimeter rises by 5.98 °C, and its heat capacity is 100 J/ ct How much energy is released p mol of H2Ol) formed? 1. An unknown piece of metal weighing 100. g is heated to 90.0 °C. It is dropped into 250 g of water t 20.0 °C. When equilibrium is reached, the temperature of both the water and piece of metal is 29.0 °C. Determine the specific heat of the metal using the fact that the energy lost by the metal must equal the energy absorbed by the water. Assume that the heat capacity of the Styrofoam cup, is negligible. 2. container, a

Explanation / Answer

1. no of mol of HCl = 100*1 = 100 mmol

   no of mol of NaOH = 100*1 = 100 mmol

heat released(q) = m*s*DT + c*DT

                  = 200*4.184*5.98+100*5.98

       = 5.6 kj

HCl+ NaOH ---> NaCl + H2O

no of mol of water formed = 0.1 mol

energy released per mol H2O(l) = -q/n = -5.6/0.1 = -56 kj/mol

2. heat lost by metal = heat gained by water

     m*s*DT = m*s*dT

100*s*(90-29) = 250*4.184*(29-20)

s = specific heat of metal = 1.54 j/g.c

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