The temperature of a 24.4 g sample of gold increases from 23.7°C to 30.8°C. If the specific heat of gold is 0.129 J/g-K, how many joules of heat are absorbed?

1 answer

To calculate the amount of heat absorbed by the sample, you can use the formula for heat transfer, which is given by:

\[ q = m \cdot c \cdot \Delta T \]

where:

  • \( q \) is the heat absorbed (in joules),
  • \( m \) is the mass of the substance (in grams),
  • \( c \) is the specific heat capacity (in J/g-K), and
  • \( \Delta T \) is the change in temperature (in °C or K).

Given:

  • Mass of gold \( m = 24.4 , \text{g} \)
  • Specific heat capacity of gold \( c = 0.129 , \text{J/g-K} \)
  • Initial temperature \( T_{\text{initial}} = 23.7 , \text{°C} \)
  • Final temperature \( T_{\text{final}} = 30.8 , \text{°C} \)

First, we need to calculate the change in temperature:

\[ \Delta T = T_{\text{final}} - T_{\text{initial}} = 30.8 , \text{°C} - 23.7 , \text{°C} = 7.1 , \text{°C} \]

Now, we can plug the values into the heat transfer formula:

\[ q = (24.4 , \text{g}) \cdot (0.129 , \text{J/g-K}) \cdot (7.1 , \text{K}) \]

Calculating this step by step:

  1. Calculate \( (24.4 , \text{g}) \cdot (0.129 , \text{J/g-K}) \): \[ 24.4 \times 0.129 = 3.1506 , \text{J/K} \]

  2. Now multiply by the change in temperature \( (7.1 , \text{K}) \): \[ q = 3.1506 , \text{J/K} \cdot 7.1 , \text{K} = 22.38926 , \text{J} \]

Rounding this to three significant figures (based on the precision of the given values), we find:

\[ q \approx 22.4 , \text{J} \]

Thus, the amount of heat absorbed by the gold is approximately 22.4 joules.