Question

Question 2 (3 points)

Answer 1

Answer:

259,000 Joules

Explanation:

To calculate the heat energy needed to change 100 grams of liquid water at 75°C to vapor at 225°C, we will do this in steps;

Step 1: Heat energy required to raise the temp of water from 75°C to 100°C

Mass of water = 100 g

Heat capacity of water = 4.184J/g °C

Temperature change (75°C to 100°C) = 25°C

Using the formula to get Quantity of heat;

Q = mcΔT

   = 100 g × 4.184 J/g °C × 25°C

  = 10,460 joules

Step 2: Heat required to change water at 100°C to vapor at 100°C

Mass of water = 100 g

Heat of vaporization = 2,256 J/g

Heat required to change water to vapor without a change in temperature is given by;

Q = m × Lv

   = 100 × 2,256 J/g

  = 225,600 Joules

Step 3: Heat energy required to raise the temperature of ice from 100°C to 225°C.

Mass of vapor = 100 g

Specific heat of gas = 1.84 J/g °C

Change in temperature (100°C to 225°C) = 125°C

Therefore;

Q = mcΔT

  = 100 g × 1.84 J/g °C × 125°C

  = 23,000 joules

Step 4: Total heat energy required

Total energy = 10,460 J + 225,600 J +  23,000 J

                      = 259,060 J

                     = 259,000 J(approx)

Therefore, heat energy required is 259,000 Joules