Why Does My Calculation of Water's Temperature Change Give the Wrong Result?

[punk_rawk_jazz]

Does anyone know why I end up with the wrong answer?

The question is: Determine the temperature change: 10 kg of water loses 232 kJ or heat

I went delta q is equal to m c delta t, the derived the equation delta t is equal to delta q divded by mc. I therefore did the math as 232 kJ divided by (10 kg times 4.2 x 10 ^3 j/kg C) and got 9.7 x 10 ^4, when the answer was supposed to be 5.5. Does anyone know what I did wrong??


Thank you in advance

 

[Diane_]

Well, I did it using your numbers and ended up with 5.5. I have two thoughts:

1) Watch your units. You're dealing with kilojoules in the numerator and joules in the denominator.

2) Watch your arithmetic: That's 232000 divided by 10 divided again by 4200.

 

[wais]

for any help!

Hi there, it looks like you have the correct formula for calculating temperature change (delta T = delta Q / (m x c)). However, the mistake in your calculation seems to be in the units. The specific heat capacity (c) of water is 4.2 J/g°C, not 4.2 x 10^3 J/kg°C. This means that the correct calculation should be 232 kJ / (10 kg x 4.2 J/g°C) = 5.5°C. Make sure to double check your units when solving equations to avoid errors. Hope this helps!