How do you find the total energy

[CrazCo]

For example

 

1 kg of water is heated from 5 degrees C to 100 degrees C to make steam. What's the total energy.

 

I tried q = mc delta t

 

and adding it with delta H = nH but I keep getting it wrong, can someone just show me how to do this one example so I can apply it to my questions.

[ydoaPs]

1 kg of water is heated from 5 degrees C to 100 degrees C to make steam. What's the total energy.

 

Emphasis mine.

[insane_alien]

well, you have the sensible heat and the latent heat combined, are you maybe required to factor in the changing heat capacity with temperature?

 

EDIT: ydoaps crazco mentioned adding on the latent heat of vapourisation.

[ydoaPs]

EDIT: ydoaps crazco mentioned adding on the latent heat of vapourisation.

so, THAT's what that was.......unfamiliar notation.

[CrazCo]

Ill show what I did

 

took the Kg to grams to get moles of water giving me 55.49 moles of water.

 

I then used delta H = 55.49 x 40.8 due to the vaporization giving me 2264 KJ

 

following this i used q =mc delta t

 

1000g x 4.19 x 95 = 398.05 kj

 

i then added them together and was wrong i think

[ydoaPs]

Ill show what I did

 

took the Kg to grams to get moles of water giving me 55.49 moles of water.

 

I then used delta H = 55.49 x 40.8 due to the vaporization giving me 2264 KJ

 

following this i used q =mc delta t

 

1000g x 4.19 x 95 = 398.05 kj

 

i then added them together and was wrong i think

 

Can you show all your units?

[CrazCo]

55.49 mols

40.8 kj/mol

1000g

4.19 kj/g*Celcius

95 degrees celcius

[insane_alien]

i got 2655kJ

 

yours is 2662kJ according to the final numbers you made

 

this is close enough. i'm not seeing a problem. what makes you think anything is wrong?

 

EDIT: i hope you meant J/gK and not kJ on the water heat capacity though.

[CrazCo]

i rounded the units.. maybe the books wrong!

[insane_alien]

what does the book say?

[CrazCo]

it was something ridiculous like 3.9 megajoules

 

i dont have it with me right now though

[insane_alien]

that is pretty high. if it's over 2.7MJ then it is flat out wrong.