Question

A closed container of water vapor is heated using 7,500 J of energy from 105°C to 140°C. What is the mass of the vapor in the container?

Answer 1

112.8 g.

Step-by-step explanation:

What is given?

We have water vapor in the closed container:

Q (heat) = 7,500 J.

c (specific heat of water vapor) = 1.9 J/g°C.

ΔT (change of temperature) = Final temperature - Initial temperature = 140 °C - 105 °C = 35 °C.

Step-by-step solution:

To solve this problem, we have to use the formula of specific heat:

`c=(Q)/(m\cdot\Delta T).`

Where c is the specific heat, in this case, the specific heat of water vapor in J/g°C; m is the mass in g; and ΔT is the change of temperature in °C.

We want to find the mass of the vapor in the container, so we have to solve for 'm' and replace the given data, like this:

`m=(Q)/(c\cdot\Delta T)=\frac{7,500\text{ J}}{1.9(J)/(g\degree C)\cdot35\degree C}=112.78\text{ g}\approx112.8\text{ g.}`

The answer would be that the mass of the vapor in the container is 112.8 g.