Question

How many moles of NO2 are needed to increase the temperature of a 333-gram block of iron from 22°C to 1300°C? (Specific heat of iron is 0.49 J/g°C).

a) 8.16 moles
b) 0.36 moles
c) 3.33 moles
d) 0.81 moles

Answer 1

To increase the temperature of the iron block, 333 grams in mass, from 22°C to 1300°C, approximately 0.36 moles of NO2 are needed.

Step-by-step explanation:

To calculate the amount of heat required to increase the temperature of the iron block, we can use the equation Q = mcΔT, where Q is the heat, m is the mass, c is the specific heat, and ΔT is the change in temperature.

In this case, the mass of the iron block is 333 grams and the specific heat is 0.49 J/g°C. The change in temperature is (1300 - 22) = 1278°C.

Plugging these values into the equation, we get:

Q = (333 g)(0.49 J/g°C)(1278 °C)

Q ≈ 210,651 J

To convert the heat from joules to moles, we need to use the molar heat capacity of NO2, which is 33.2 J/mol°C. We can use the equation Q = nCΔT, where n is the number of moles, ΔT is the change in temperature, and C is the molar heat capacity.

Setting up the equation, we have:

210,651 J = n(33.2 J/mol°C)(1278 °C)

Solving for n, we get:

n ≈ 0.36 moles