Joules required to heat/how much heat is released

jacob95

1. The problem statement, all variables and given/known data

1.)How many joules are required to heat 250 grams of liquid water from 25 C to 100 C

2.)How much heat is released when 200 grams of steam condenses?

2. Relevant equations

q=m*(delta) t*c
q=(delta)H*m



3. The attempt at a solution

1.)q=250g*75°C*4.186joules ? = 74 487joules ?
74 487 joules = 18,758 cal?
2.)

rock.freak667

For the first one, you have the formula

Q=mcΔT, so what is c for water ? You are given m and you can get ΔT (the change in temperature). So just plug in the numbers.

For the second one. What is the latent heat of water for this case of going from a gas to a liquid?

jacob95

so would it be

q=250g*75°C*4.186j=78487.5 joules?
or
q=250g*75°C*1

then I would have to convert it to calories

78 487 joules = 18 758 cal?

jacob95

yes?

rock.freak667

It would be the first one since c= 4.186 J/g°C

jacob95

thanks

what does ΔH stand for in

q=ΔH*m?

nayfie

I think that's the latent heat.