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# Chem help please me..?

1. _____________ is the direct conversion from the solid phase to the gas phase.

2. The heat of fusion of water is 335 J/g, the heat of vaporization of water is 2.26 kJ/g, the specifc heat of ice is 2.05 J/deg/g, the specific heat of steam is 2.08 J/deg/g and the specific heat of liquid water is 4.184 J/deg/g. How much heat would be needed to convert 10.57 g of ice at -7 °C to steam at 142 °C?

3. The heat of fusion of water is 335 J/g. How much heat would be required to melt 55.2 g of ice?

4. The heat of fusion of water is 335 J/g, the heat of vaporization of water is 2.26 kJ/g, and the specific heat of water is 4.184 J/deg/g. How many grams of ice at 0 ° could be converted to steam at 100 °C by 7,573 Joules of heat?

5. The heat of vaporization of water is 2.26 kJ/g. How much heat is needed to change 2.07 g of water to steam?

### 2 Answers

- ColinLv 77 years agoFavorite Answer
5. The heat of vaporization of water is 2.26 kJ/g. How much heat is needed to change 2.07 g of water to steam?

Assuming it is water at 100C turning to steam at 100C, then

Heat required = 2.07 x 2.26 kJ

This question should really state start and finish temperatures.

Source(s): Rtc - 7 years ago
1. Sublimation

2.(tips)

You will have to calculate the energy required, part-by-part. You have to understand the phases that it went through! Now look at this:

Ice -> water -> steam

So, here you have to calculate the energy:

E1: (The energy required to change the ice's temperature from -7 to 0 degree celcius. The ice havent melts into water. HAVENT! Use Q=mcƟ )

E2: (The energy required to convert the ice to water at 0Degree celcius. In this phase, the energy is used to break the bond inside the ice to change to water form, and therefore the temperature of water is still 0 degree celcius. The energy is not used to raise the temperature of the water. Use Q=ml)

E3: (The energy required to change the temperature of water from 0 to 100)

E4: (The energy required to change the state of the water to steam at 100 degree celcius. It remains the temperature, because the energy is used to break the bond in water to form steam. Use Q=ml)

E5: (The energy required to change the temperature of steam from 100 to 142 degree celcius. Use Q=mcƟ)

Therefore, the total energy required would be: E1+E2+E3+E4+E5

Good luck!

Source(s): I took foundation in science in UTAR :D