If you add 700 kJ of heat to 700 g of water at 70.0°C, how much water is left in the container? The latent heat of vaporization of water is 2.26 × 10⁶ J/kg and its specific heat is 4190 J/(kg∙K). A) 429 g B) 258 g C) 340 g D) 600 g E) none

Question

Quizplus · Accepted Answer

First, we need to calculate the initial energy stored in the water:
Q = mcΔT
Q = 0.7 kg × 4190 J/(kg∙K) × (70.0°C - 0°C)
Q = 206,090 J
Next, we need to calculate how much energy is needed to completely vaporize the water:
Q = mL
206,090 J = 0.7 kg × L
L = 294,414 J/kg 
Now we can calculate how much water is vaporized with the additional 700 kJ of heat:
m = Q/L = 700,000 J / 294,414 J/kg ≈ 2.38 kg
Therefore, the amount of water left in the container is:
700 g - 2.38 kg ≈ 0.429 kg = 429 g (choice A).

If You Add 700 KJ of Heat to 700 G