How much energy is needed to change the temperature of 25.00 mL of water from 10

Question

How much energy is needed to change the temperature of 25.00 mL of water from 10.0 degree C to 95.0 C degree? In a experiment, 74.3 g of metallic copper was heated to 100.0 degree C and then quickly dropped into 200.0 mL of water in a calorimeter. The heat capacity of the calorimeter with the water was 875 j/ degree C the initial temperature of the calorimeter was 27 degree 5 C, and the final temperature after addition of the metal was 29.8 degree C what is the value of the molar heat capacity of copper?

Explanation / Answer

ANSWER TO Q4: Energy needed (E) = Cp X no. of moles of wter (n) X change in temprature (T")

convert volume of water to mass of water and then mass of water to moles of water as shown

mass density X volume = 25 X 1.00 = 25g

moles of water = 25 /18 = 1.38moles , because molar mass of water is 18g

Q5

this question can be solved by using the following hint

Heat lost bycopper = heat gained by calorimeter

Cp(Cu) X (100 - 29.5) X 74.3 = Cp (Calorimeter) X (29.5-27.5) X 200

density of water = 1.0g/mL

getting the value of Cp(Cu) from above can coverted molar value by deviding with molar mass of Cu.

Cp (Calorimeter) is not clear that prevents me to give you exact value,

chenge in temperature = (final temprature - initial temperature) = (95 - 10) = 85 oC

therefore E = 75.38 X 1.38 X 85 = 8842J = 8.9KJ

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