Specific heat is the amount of energy needed to increase a gram of pure substance by one degree. The specific heat of a substance depends on its molecular structure and its phase. This scientific discovery has stimulated studies on thermodynamics, energy conversion and the work of a system. Specific heat and thermodynamics are widely used in chemistry, nuclear and aerodynamic engineering, as well as in everyday life. Examples are the radiator and the cooling system of a car. If you want to know how to calculate specific heat, just follow these steps.
Steps
Method 1 of 2: Learn the Fundamentals
Step 1. Familiarize yourself with the terms that are used to calculate specific heat
It is important to be familiar with the terms that are used to calculate specific heat before learning the formula. You need to recognize the symbol for each term and understand what it means. Here are the terms commonly used in the equation for calculating the specific heat of a substance:
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Delta or "Δ" symbol represents change in a variable.
For example, if your first temperature (T.1) is 150 ºC and the second (T2) is 20 ° C, then ΔT, the temperature change, is given by 150 ºC - 20 ºC = 130 ºC.
- The mass of the sample is represented by "m".
- The amount of heat is represented by "Q" and is calculated in "J" or Joules.
- "T" is the temperature of the substance.
- The specific heat is represented by the "c".
Step 2. Learn the equation for specific heat
Once you are familiar with the terms used, you will need to learn the equation to find the specific heat of a substance. The formula is: c = Q / mΔt.
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You can manipulate this formula if you want to find the variation in the amount of heat instead of the specific heat. Here's how it becomes:
ΔQ = mcΔt
Method 2 of 2: Calculate Specific Heat
Step 1. Study the equation
First, you should analyze the equation to get an idea of what you need to do to find the specific heat. Let's look at this problem: “Find the specific heat of 350 g of an unknown material when 34,700 J of heat is applied and the temperature rises from 22ºC to 173ºC”.
Step 2. Make a list of known and unknown factors
Once you are comfortable with the problem, you can mark each known variable and the unknown ones. Here's how to do it:
- m = 350 g
- Q = 34,700 J
- Δt = 173 ºC - 22 ºC = 151 ºC
- cp = unknown
Step 3. Substitute known values into the equation
You know all the values except "c", so you should substitute the rest of the factors in the original equation to find "c". Here's how to do it:
- Original equation: c = Q / mΔt
- c = 34.700 J / (350 g x 151 ºC)
Step 4. Solve the equation
Now that you've entered the known factors into the equation, just do some simple arithmetic. Specific heat, the final answer, is 0.65657521286 J / (g x ºC).
- c = 34.700 J / (350 g x 151 ºC)
- c = 34.700 J / (52.850 g x ºC)
- cp = 0, 65657521286 J / (g x ºC)
Advice
- Metal heats up faster than water due to its low specific heat.
- A calorimeter can sometimes be used with a heat transfer during a physical or chemical change.
- When solving the specific heat equation, simplify the units of measurement, if possible.
- The units for specific heat are Joules. But calories are still used for calculations involving water.
- Thermal variations are greater in materials with low specific heat, all other conditions being equal.
- The specific heat of many objects can be found online to check your work.
- Learn the formula for calculating the specific heat of food. cp = 4.180 x w + 1.711 x p + 1.928 x f + 1, 547 x c + 0.908 x a is the equation used to find the specific heat of food where "w" is water, "p" is protein, "f" is fat, "c" is carbohydrate and "a" is ash. This equation takes into account the mass fraction (x) of all food components. The calculation of the specific heat is expressed in kJ / (kg - K).
