# Chemistry

posted by .

How much energy does it take to convert 0.800 kg ice at -20.°C to steam at 250.°C?

Specific heat capacities:
ice, 2.1 J g-1 °C-1
liquid, 4.2 J g-1 °C-1
steam, 2.0 J g-1 °C-1

ΔHvap = 40.7 kJ/mol, ΔHfus = 6.02 kJ/mol

This is what I tried to do:
Heating ice
q= ( 2.1 J g-1 °C-1)*(800g)*(20°C)=...

Ice to water
q=(6.02 kJ / mol)*(800g)*(1 mol/18g)=...

Heating water
q=(4.2 J g-1 °C-1)*(800g) * (20)
Is the change in temperature still 20? This is where I am confused...

Water to steam
q=(40.7 kJ/mol)*(800g)*(1 mol/ 18g)=...

Heating steam
q=(2.0 J g-1 °C-1)*(800g)*(change in temp=???? 250-(-20)???)

Please can you check if I am doing this right and I need help with the change in temperature

• Chemistry -

Portions may be right but most steps leave out something. Here is how you do it.

q1 = heat to move T of ice from -20 to zero C.
q1 = mass ice x specific heat ice x (Tfinal-Tinitial). Tfinal = 0 and Tinitial = -20; therefore, Tfinal-Tinitial = 0 -(-20) = +20.

q2 = heat to melt the ice at zero C to liquid water at zero C.
q2 = mass ice x heat fusion.

q3 = heat to move T from zero C to 100 C.
q3 = mass water x specific heat water x 100 (that is Tfinal-Tinitial) or (100-0 = 100).

q4 = heat to convert from liquid water at 100 C to steam at 100 C.
q4 = mass water x delta Hvap.

q5 = heat to move T of steam at 100 C to steam at 250 C.
q5 = mass x specific heat steam x (Tfinal-Tinitial).
Total energy required is
qtotal = q1 + q2 + q3 + q4 + q5.

## Similar Questions

1. ### Physics

How much heat is added to a 10.0 g of ice at -20.0 degrees Celsius to convert it to steam at 120.0 degrees Celsius?
2. ### chemistry

Given that the specific heat capacities of ice and steam are 2.06 J/g°C and 2.03 J/g°C, the molar heats of fusion and vaporization for water are 6.02 kJ/mol and 40.6 kJ/mol, respectively, and the specific heat capacity of water is …
3. ### CHEMISTRY

Given that the specific heat capacities of ice and steam are 2.06 J/g°C and 2.03 J/g°C, the molar heats of fusion and vaporization for water are 6.02 kJ/mol and 40.6 kJ/mol, respectively, and the specific heat capacity of water is …
4. ### chemistry

Calculate the energy in the form of heat, in kJ, required to convert 225 grams of liquid water at 21.0 °C to steam at 115 °C. Heat of fusion = 0.333 kJ/g; heat of vaporization = 2.26 kJ/g; specific heat capacities: liquid water = …
5. ### chemistry

the heat of fusion water is335 J/g. The heat of evaporization of water is 2.26 kJ/g, the specific 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 …
6. ### CHEMISTRY

Consider a 58.4 g sample of H2O(g) at 125°C. What phase or phases are present when -162 kJ of energy is removed from this sample?
7. ### Chemistry

22.) The molar heats of fusion and vaporization for water are 6.02 kJ/mol and 40.6 kJ/mol, respectively, and the specific heat capacity of liquid water is 4.18 J/gC. (1) What quantity of heat is required to melt 25.0 g of ice at 0C?
8. ### Phase Changes

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 …
9. ### Physical Science

A 5.00 kg block of ice at –25 oC is converted to steam at 125 oC. How much energy (in kilojoules) is expended in this process?
10. ### chemistry

1. Given that 50 grams of ice is heated at -20.0 °C to steam at 135.0 °C. i. Show the graph of the changes from ice to steam ii. Calculate the energy needed to change the ice to steam Please use these values: Heat of fusion = 334.16 …

More Similar Questions