Question

3350 J of heat is required to raise the temperature of a sample of AlF3 from 250C to 800C. What is the mass of the sample?

Answer 1

Answer:

1. Look up the specific heat capacity of AlF₃
2. Calculate ΔT
3. Calculate the mass of AlF₃

Explanation:

The formula for for the heat (q) absorbed by an object is

 q = mCΔT, where

m = the mass of the sample

 C = the specific heat capacity of the sample. and

ΔT = the change in temperature

1. What you must do

• Look up the specific heat capacity of AlF₃
• Calculate ΔT
• Calculate the mass of AlF₃

2. Sample calculation

For this example, I assume that the specific heat capacity of AlF₃ is 1.16 J·K⁻¹mol⁻¹ .

(a) Calculate ΔT  

$\Delta T = T_{\text{f}} - T_{\text{i}} = 800 \, ^{\circ}\text{C} -250 \, ^{\circ}\text{C} = 550 \, ^{\circ}\text{C}$

(b) Calculate m

$\begin{array}{rcl}\text{3350 J} & = & m \times 1.16 \text{ J}\cdot\text{K}^{-1} \text{mol}^{-1}\times \text{550 K}\\3350 & = & m \times \text{638 g}^{-1}\\m & = &\dfrac{3350}{\text{638 g}^{-1}}\\\\ & = & \text{ 5.2 g}\\\end{array}$