Answer:
274.5g of CCl₂F₂
Explanation:
To freeze 200g of water yo need to decrease the temperature of water from 15°C to 0°C and then change its phase from solid to liquid. That is:
Decreasing temperature:
q = 4.18J/gK ×200g× (15°C - 0°C)
q = 12540J
In the change of phase:
q = 334 J/g × 200g
q = 66800J
Thus, total heat is:
12540J + 66800J = <em>79340J</em>.
If this heat comes from CCl₂F₂ vaporization, must be evaporated:
79340J × (1g / 289J) = <em>274.5g of CCl₂F₂</em>
The reaction equation is Mg(OH)2 + 2HCl = MgCl2 + H2O. The mol number of Mg(OH)2 is 2.96/58=0.051 mol. So we need 0.051*2=0.102 mol HCl to neutralize. The volume is 0.102/0.126=0.810 L =810 mL.
