Advertisements
Advertisements
Question
Decide the unit for specific heat capacity.
Advertisements
Solution
- The amount of heat (Q) required to change the temperature of a substance is directly proportional to:
a. the mass of the substance (m).
b. change in temperature of the substance (ΔT).
∴ Q ∝ m and Q ∝ ΔT
∴ Q ∝ mΔT
∴ Q = cmΔT ....(1)
where ‘c’ is specific heat or specific heat capacity of a substance. From equation (1),
c = `"Q"/("m" Delta "T")` ....(2) - SI unit:
As SI unit of heat is J, mass is kg and change in temperature is °C, SI unit of specific heat capacity is J/kg °C - C.G.S. unit:
As CGS unit of heat is calorie, mass is g and change in temperature is °C, CGS unit of specific heat capacity is cal/g °C
APPEARS IN
RELATED QUESTIONS
In an experiment on the specific heat of a metal, a 0.20 kg block of the metal at 150 °C is dropped in a copper calorimeter (of water equivalent 0.025 kg) containing 150 cm3 of water at 27 °C. The final temperature is 40 °C. Compute the specific heat of the metal. If heat losses to the surroundings are not negligible, is your answer greater or smaller than the actual value for the specific heat of the metal?
Given below are observations on molar specific heats at room temperature of some common gases.
| Gas |
Molar specific heat (Cv) (cal mol–1 K–1) |
| Hydrogen | 4.87 |
| Nitrogen | 4.97 |
| Oxygen | 5.02 |
| Nitric oxide | 4.99 |
| Carbon monoxide | 5.01 |
| Chlorine | 6.17 |
The measured molar specific heats of these gases are markedly different from those for monatomic gases. Typically, molar specific heat of a monatomic gas is 2.92 cal/mol K. Explain this difference. What can you infer from the somewhat larger (than the rest) value for chlorine?
You have a choice of three metals A, B, and C, of specific heat capacities 900 Jkg-1 °C-1, 380 Jkg-1 °C-1 and 460 Jkg-1 °C-1 respectively, to make a calorimeter. Which material will you select? Justify your answer.
Water in lakes and ponds do not freeze at once in cold countries. Give a reason is support of your answer.
45 g of water at 50°C in a beaker is cooled when 50 g of copper at 18° C is added to it. The contents are stirred till a final constant temperature is reached. Calculate this final temperature. The specific heat capacity of copper is 0.39 J g-1K-1 and that of water is 4.2 J g-1K-1. State the assumption used.
Explain the meaning of green house effect.
How does green house effect help in keeping the temperature of earth’s surface suitable for living of human beings?
State the impact of global warming on life on the earth.
How will global warming disturb the ecological balance?
State three ways to minimize the global warming.
What is meant by specific heat capacity?
The product of mass and specific heat is known as ..........
If substances A and B are liquids then which one would be more useful in car radiators?
Given: Specific heat capacity’A’ 3.8 J/g /K. Specific heat capacity ‘B’ 0.4 J/g /K.
Some heat is provided to a body to raise its temperature by 25°C. What will be the corresponding rise in temperature of the body as shown on the Kelvin scale?
Will the value of specific heat’capacity and specific latent heat of a substance change if the scale is °F instead of °C?
Derive Mayer’s relation.
If 'Cp' and 'Cv' are molar specific heats of an ideal gas at constant pressure and volume respectively. If 'λ' is the ratio of two specific heats and 'R' is universal gas constant then 'Cp' is equal to ______.
A monoatomic gas of pressure 'P' having volume 'V' expands isothermally to a volume '2V' and then adiabatically to a volume '16V'. The final pressure of the gas is ______.
(ratio of specific heats = `5/3`)
A metal ball of heat capacity 50J/°C loses 2000 J of heat. By how much will its temperature fall?
