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Grade upto college level Thermal Physics

When a piece of metal at temperature 100 C is dropped in water at 20 C, the nal equilibrium temperature is found to be 30 C. Assume that the heat is exchanged only between the and water.The ratio of mass of water to that of the metal piece is 5 : 1 and speci c heat capacity of water is 1 cal/g-C. Calculate the speci c heat capacity of the metal.

Profile image of Deepak Patra
12 Years agoGrade upto college level
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ApprovedApproved Tutor Answer1 Year ago

To determine the specific heat capacity of the metal, we can apply the principle of conservation of energy, which states that the heat lost by the metal will equal the heat gained by the water. Let's break this down step by step.

Understanding the Heat Exchange

When the hot metal is placed in the cooler water, heat will flow from the metal to the water until they reach thermal equilibrium. In this scenario, we have:

  • Initial temperature of the metal, Tm = 100°C
  • Initial temperature of the water, Tw = 20°C
  • Final equilibrium temperature, Tf = 30°C
  • Mass ratio of water to metal = 5:1

Setting Up the Equation

Let’s denote the mass of the metal as mm and the mass of the water as mw. Given the ratio of their masses, we can express the mass of water as:

mw = 5 * mm

Now, we can use the formula for heat transfer:

Heat lost by metal = Heat gained by water

This can be expressed mathematically as:

mm * cm * (Tm - Tf) = mw * cw * (Tf - Tw)

Substituting Known Values

We know that:

  • cw (specific heat capacity of water) = 1 cal/g°C
  • Tm = 100°C
  • Tw = 20°C
  • Tf = 30°C

Substituting these values into the equation gives:

mm * cm * (100 - 30) = (5 * mm) * 1 * (30 - 20)

Simplifying the Equation

We can simplify this equation:

mm * cm * 70 = 5 * mm * 1 * 10

Notice that mm cancels out from both sides:

cm * 70 = 50

Calculating the Specific Heat Capacity

Now, we can solve for cm:

cm = 50 / 70

cm = 0.7143 cal/g°C

Final Thoughts

The specific heat capacity of the metal is approximately 0.714 cal/g°C. This value indicates how much heat energy is required to raise the temperature of one gram of the metal by one degree Celsius. Understanding this concept is crucial in thermodynamics and helps in various applications, from engineering to environmental science.