is heating water endothermic or exothermic? (1 Viewer)

[pinkcupcakes]

is heating water endothermic or exothermic?


im doing calcultions in change in enthalphy (heat)
and well
im using the formula:

change in heat [ joules ] = - mass [grams] x [specific heat capaticity] x change in temp. [K]


and if change in heat is negative.. the reaction must be EXOTHERMIC ?
however, water being heated does not sound like an exothermic reaction as it absorbs heat ?

q: how much energy will be requied to raise the temp. of 1 L of water in a kettle from 17 to 100 C?

I got -347 kJ.
thus an exothermic ?
is the formula im using wrong ?


Thankss

 

[nat_doc]

its endo. cause heat is absorbed . that formula is for combustion. they put a neg. sign there because combustion is always exo, so when u punch in numbers, you get a postive number for the value of the molar heat of combustion... if the english in this response is bad, excuse ti cause i cbf.

 

[danal353]

It simply means that 347kJ of energy has been used (i.e. taken away from combustion of the fuel) to heat up the water. As said above, water heating up would be endothermic

 

[Pwnage101]

is heating water endothermic or exothermic?


im doing calcultions in change in enthalphy (heat)
and well
im using the formula:

change in heat [ joules ] = - mass [grams] x [specific heat capaticity] x change in temp. [K]


and if change in heat is negative.. the reaction must be EXOTHERMIC ?
however, water being heated does not sound like an exothermic reaction as it absorbs heat ?

q: how much energy will be requied to raise the temp. of 1 L of water in a kettle from 17 to 100 C?

I got -347 kJ.
thus an exothermic ?
is the formula im using wrong ?


Thankss

Your formula is indeed wrong - There should NOT be a minus sign. Hence when the temperature decreases, i.e. the change in temperature is negative, then your answer will be negative, indicating an exothermic reaction, since heat has been liberated.