Understanding Specific Heat Capacity and Heat Calculation for a Substance

Understanding the specific heat capacity of a substance is a crucial skill in both academic and practical applications. This article explains how to calculate the heat required to raise the temperature of a given mass of a substance using its specific heat capacity. By the end of this guide, you will be able to solve such problems confidently.

Understanding Specific Heat Capacity

The specific heat capacity (Cp) of a substance is defined as the amount of heat energy required to raise the temperature of one gram of that substance by one degree Celsius (or one Kelvin). It is an important physical property that helps us understand how substances react to changes in temperature.

Calculating Heat (Q)

To calculate the heat (Q) required to raise the temperature of a substance, we use the formula:

Q m × c × ΔT

where:

Q is the heat energy in joules (J) m is the mass of the substance in grams (g) c is the specific heat capacity of the substance in joules per gram per degree Celsius (J/g°C) ΔT is the change in temperature in degrees Celsius (°C)

Example Calculation

Suppose we have a substance with a specific heat capacity of 3 J/g°C, and we need to raise the temperature of 1 gram of this substance by 5 °C. Let's walk through the calculation step-by-step.

m 1 gram

c 3 J/g°C

ΔT 5 °C

The formula we will use is:

Q m × c × ΔT

Substituting the values:

Q 1 gram × 3 J/g°C × 5 °C

Q 15 J

This means that 15 joules of heat are required to raise the temperature of 1 gram of the substance by 5 °C.

Additional Examples

Here are a few more examples to help solidify your understanding:

Example 1

M 1 gram, CpM 3 J/g-deg C, ΔT 5 deg C

Q M × CpM × ΔT

Q 1 gram × 3 J/g-deg C × 5 deg C

Q 15 J

Example 2

Given:

q 3 J (to raise 1 gram by 1 °C) ΔT 5 °C

Since it takes 3 J to raise 1 gram by 1 °C, for a 5 °C increase, we need:

q 3 J/°C × 5 °C

q 15 J

Example 3

Using the formula:

q m × C × ΔT

q 1 g × 3 J/g°C × 5 °C

q 15 J

Again, the units of grams (g) and degrees Celsius (°C) cancel out, leaving joules (J).

Conclusion

Understanding and applying the concept of specific heat capacity is essential for various fields, including chemistry, physics, and engineering. By using the formula Q m × c × ΔT, you can calculate the amount of heat required to raise the temperature of a substance. Practice these examples to ensure you grasp the concept thoroughly.