1. An 8.7-g ice cube is placed into 255g of water. Calculate the temperature cha

Question

1. An 8.7-g ice cube is placed into 255g of water. Calculate the temperature change in the water upon the complete melting of the ice. Assume that all of the energy required to melt the ice comes from the water. Express your answer in terms of the initial temperature of water, T.

ANS. I don't know how to get to the asnwer ---> = -0.033T-2.6C

2. Suppose that 1.12g of rubbing alcohol (C3H8O)evaporates from a 69.0g aluminum block. If the aluminum block is initially at 25?C, what is the final temperature of the block after the evaporation of the alcohol? Assume that the heat required for the vaporization of the alcohol comes only from the aluminum block and that the alcohol vaporizes at 25?C. Heat of vaporization of the alcohol at 25 ?C is 45.4 kJ/mol

3. Calculate the amount of heat required to completely sublime 43.0g of solid dry ice (CO2) at its sublimation temperature. The heat of sublimation for carbon dioxide is 32.3 kJ/mol.

Explanation / Answer

1. Latent heat of fusion Ql = 335 J/gram

For 8.6 g , heat required = 333.5 x 8.6J = 2918.85 J = 2.91885 kJ

As this heat is taken from the water, Q = m x Cp x delta T (where delta T is the change in the temperature)

Cp = specific heat of water = 4.18 kJ /(kg°C)

mass m = 255 g = 0.255 kg

So, 2.91885 kJ = 0.255 x 4.18 kJ/kg°C x (T1-T2)

T1-T2 = 2.91885/(4.18 x 0.255) = 2.74°

T2 = T1 - 2.74°

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.