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.

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

 

Emphasis mine.

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.

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

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

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

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?

55.49 mols

40.8 kj/mol

1000g

4.19 kj/g*Celcius

95 degrees celcius

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.

i rounded the units.. maybe the books wrong!

what does the book say?

it was something ridiculous like 3.9 megajoules

 

i dont have it with me right now though

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