[Physics]heat and calorimeter

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r/AskPhysics
[heat and calorimeter] I can't solve a question correct.
u/SuriAttacker
Hey there guys, first of all English is not my main language so it will be a little hard for me to say things in english. I am dutch native speaker so I will translate most of the things in english using google translator. I hope you guys are okay with that.

Task : One wants the heat capacity of a calorimeter. It does so by one in the empty calorimeter, which has a temperature of 19.3 C, 50 grams of benzene with a temperature of 13, 5 c is added. This drops the temperature of the calorimeter to 15, 9 c.

a)Calculate the value of the heat capacity of this calormeter.

b)Directly after this (the temperature of the calorimeter is still 15.9 *c), a Platinum bullet is added, which has a mass of 15.0 gram, in the calorimeter. This platinum ball has been kept in a glass flame beforehand; the temperature of the calorimeter runs to 23.7 c. determine the temperature of the gas flame

Okay, I had no problem answering a , here is my answer -> http://i.imgur.com/gOZuEfL.jpg and according to the book the answer is correct.

Now I've tried the same thing with b , but after getting the final answer it seemed that it's not correct according to my book answer, the answer should be 604 *c. I still have no idea what I did wrong... here is the calculation I did : http://i.imgur.com/7t7Xqdu.jpg It might be a little annoying since it's written in dutch, but I do hope you understand. Any help is appreciated, thank you