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171 mL of H2O), initially at 82.4°C, is cooled to 0°C. How many moles of ice (at 0°C) can
be melted with the energy given off by water? Be sure that your answer has at least one
decimal place.

Respuesta :

1) Energy released from water

List known data

Volume: 171 mL H2O

Initial temperature: 82.4ºC

Final temperature: 0ºC

c=4.184 J/gºC

List unknown data

Energy released:

2) Set the equation

q=mcΔT

3) Change volume into mass

[tex]\text{mass of H}_2O=171mL\cdot\frac{1g}{1mL}=171gH_2O[/tex]

4) Replace known values

[tex]q=(171gH_2O)(4.184\frac{J}{gºC})(0ºC-82.4ºC)=-58954.23\text{ J}[/tex]

The total energy released -58954.23 J

5) The energy required to melt ice

List known data

q= -58954.23 J

ΔH(fus)= 334 J/g

List unknown data

m=

6) Set the equation

q=mΔH(fus)

7) Replace known values

+58954.23 J = m (334 J/g)

8) Solve the equation for m.

[tex]m=\frac{+58954.23\text{ J}}{\frac{334J}{g}}=176.51g[/tex]

9) Find moles

[tex]\text{molesofH}_2O=176.51gH_2O\cdot\frac{1molH_2O}{18.01g}=9.80molH_2O[/tex]

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