Question

Coffee Cup Calorimetry: Specific Heat

[Review Topics] (References) Use the References to access important values if needed for this question. In the laboratory a "coffee cup" calorimeter, or constant pressure calorimeter, is frequently used to determine the specific heat capacity of a solid, or to measure the enthalpy of a solution phase reaction. There Seiring Since the cup itself can absorb energy, a separate experiment is needed to determine the heat capacity of the calorimeter. This is known as calibrating the calorimeter and the value determined is called the calorimeter constant. One way to do this is to use a common metal of known heat capacity. In the laboratory a student heats 98.54 g copper to 98.67 °C and carefully lowers it into a cup containing 84.81 g water at 21.61 °C. She measures the final temperature to be 29.02 °C. Using the accepted value for the specific heat capacity of copper (See the References tool), calculate the calorimeter constant. Calorimeter Constanta J°C. Submit Answer Retry Entire Group 3 more group attempts remaining

Answer 1

Coffee cup Calorimeter constant calculation

q_copper = q_H2O + q_calorimeter

[m_m x Cp_m x (Ti - Tf) ] = [m_w x Cp_w x (Tf - Tc) ] + [C x (Tf - Tc)]

where C = heat capacity of calorimeter; m = mass; c = specific heat: ΔT = temp. difference; m = copper metal; w = water

m_m = 98.54 g; m_w = 84.81 g; Cp_w = 4.184 J/g/°C; Cp_m = 0.092 cal/g.⁰C = 0.385 J/g.⁰c

(Tf - Tc) = 29.02 - 21.61 = 7.41°C; (Ti - Tf) = 98.67 - 29.02 = 69.65 °C;

[98.54 g x 0.385 J/g.⁰C x 69.65 °C] = [84.81 g x 4.184 J/g.°C x 7.41°C] + [ C x 7.41°C]

[98.54 g x 0.385 J/g.⁰C x 69.65 °C] - [84.81 g x 4.184 J/g.°C x 7.41°C] = [ C x 7.41°C]

C = 12.9729886 J / 7.41°C = 1.75074070175 J/°C

Calorimeter constant = 1.751 J/°C

[Review Topics] (References) Use the References to access important values if needed for this question. In the laboratory a "coffee cup" calorimeter, or constant pressure calorimeter, is frequently used to determine the specific heat capacity of a solid, or to measure the enthalpy of a solution phase reaction. There Seiring Since the cup itself can absorb energy, a separate experiment is needed to determine the heat capacity of the calorimeter. This is known as calibrating the calorimeter and the value determined is called the calorimeter constant. One way to do this is to use a common metal of known heat capacity. In the laboratory a student heats 98.54 g copper to 98.67 °C and carefully lowers it into a cup containing 84.81 g water at 21.61 °C. She measures the final temperature to be 29.02 °C. Using the accepted value for the specific heat capacity of copper (See the References tool), calculate the calorimeter constant. Calorimeter Constanta J°C. I 1.751 Submit Answer Retry Entire Group 3 more group attempts remaining

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