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The specific heat capacity of water was found by adding hot copper to water in a copper calorimeter - Leaving Cert Physics - Question 2 - 2007

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The specific heat capacity of water was found by adding hot copper to water in a copper calorimeter. The following data was recorded. mass of calorimeter: 55.7 g ma... show full transcript

Worked Solution & Example Answer:The specific heat capacity of water was found by adding hot copper to water in a copper calorimeter - Leaving Cert Physics - Question 2 - 2007

Step 1

Describe how the copper was heated and how its temperature was measured.

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Answer

To heat the copper, it was placed in boiling water until it reached thermal equilibrium with the water, ensuring that it was uniformly hot throughout. The temperature of the copper was measured using a thermometer, which is inserted into the water surrounding the copper, providing a clear reading of the temperature before it was introduced into the calorimeter.

Step 2

(i) the energy lost by the hot copper

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Answer

The energy lost by the hot copper can be calculated using the formula:

E=mimescimesriangleTE = m imes c imes riangle T

Where:

  • m=0.32imes103extg=320extgm = 0.32 imes 10^{3} ext{g} = 320 ext{g}
  • c=390extJkg1extK1c = 390 ext{J kg}^{-1} ext{K}^{-1}
  • riangleT=(99.5°C21.0°C)=78.5°C riangle T = (99.5°C - 21.0°C) = 78.5°C

Converting grams to kilograms:

  • m=0.32extkgm = 0.32 ext{ kg}

Thus, the energy can be calculated as:

E=0.32imes103imes390imes78.5=9245.57extJE = 0.32 imes 10^{3} imes 390 imes 78.5 = 9245.57 ext{ J}

or approximately 9246 J.

Step 3

(ii) the specific heat capacity of water.

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Answer

The specific heat capacity of water can be calculated from the heat gained by water, which is equal to the heat lost by the copper:

9247.50=(massextofwater)imes(cw)imes(finalexttempinitialexttemp)9247.50 = (mass ext{ of water}) imes (c_{w}) imes (final ext{ temp} - initial ext{ temp})

Taking the mass of water as mw=101.2extg55.7extg=45.5extg=0.0455extkgm_{w} = 101.2 ext{g} - 55.7 ext{g} = 45.5 ext{g} = 0.0455 ext{ kg} and substituting into the equation gives:

cw=Emwimes(TfinalTinitial)c_{w} = \frac{E}{m_{w} imes (T_{final} - T_{initial})}

Substituting in the values:

cw=92460.0455imes(21.016.5)=4.038imes103extJkg1extK1c_{w} = \frac{9246}{0.0455 imes (21.0 - 16.5)} = 4.038 imes 10^{3} ext{ J kg}^{-1} ext{ K}^{-1}

Thus, the specific heat capacity of water is approximately 4.04imes103extJkg1extK14.04 imes 10^{3} ext{ J kg}^{-1} ext{ K}^{-1}.

Step 4

Give two precautions that were taken to minimise heat loss to the surroundings.

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Answer

  1. Insulating the calorimeter with insulating materials (like a lid or insulating foam) helps reduce heat loss.
  2. Avoiding splashes and ensuring that the calorimeter is not exposed to air will help maintain temperature.

Step 5

Explain why adding a larger mass of copper would improve the accuracy of the experiment.

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Answer

Adding a larger mass of copper would ensure a larger heat transfer, resulting in a more noticeable temperature change in the water. This improves the sensitivity of the measurements, as it minimizes the effects of heat loss and provides more data for calculating the specific heat capacity.

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