Compounds like \(\mathrm{CCl}_{2} \mathrm{~F}_{2}\) are known as chlorofluorocarbons, or CFCs. These compounds were once widely used as refrigerants but are now being replaced by compounds that are believed to be less harmful to the environment. The heat of vaporization of \(\mathrm{CCl}_{2} \mathrm{~F}_{2}\) is \(289 \mathrm{~J} / \mathrm{g}\). What mass of this substance must evaporate to freeze \(200 \mathrm{~g}\) of water initially at \(15^{\circ} \mathrm{C} ?\) (The heat of fusion of water is \(334 \mathrm{~J} / \mathrm{g} ;\) the specific heat of water is \(4.18 \mathrm{~J} / \mathrm{g}-\mathrm{K} .)\)

= -12540 J #Step 2: Calculate the energy required to freeze the water# Next, we need to find the energy required to freeze 200g of water at 0°C. We can use the formula: q = mL Where q is the heat energy, m is the mass of water, and L is the heat of fusion of water (334 J/g). q = (200 g)(334 J/g) = 66800 J #Step 3: Calculate the total energy required# Now, we can find the total energy required to cool and freeze the water by adding the energy from step 1 and step 2: Total energy = -12540 J + 66800 J = 54260 J #Step 4: Find the mass of CCl₂F₂ that must evaporate# Finally, we can find the mass of CCl₂F₂ that must evaporate using the heat of vaporization of CCl₂F₂ (289 J/g) and the total energy calculated in step 3. We can use the formula: mass = q / heat of vaporization mass = 54260 J / 289 J/g = 187.75 g Therefore, 187.75 grams of CCl₂F₂ must evaporate to freeze 200 grams of water initially at 15°C.