Question

A researcher studying the nutritional value of a new candy places a 5.00-gram sample of the candy inside a bomb calorimeter and combusts it in excess oxygen. The observed temperature increase is 2.25 °C. If the heat capacity of the calorimeter is 39.90 kJ·K–1, how many nutritional Calories are there per gram of the candy?

Answer 1

@maheshmeghwal9

Answer 2

\[q=(C)(\Delta T)\] i don't believe the mass has anything to do with this problem because you have the heat capacity for the calorimeter, and by the fact there is nothing to cancell out the grams. Change you degrees C into K

Answer 3

q= (39.90kj)(275.4)

Answer 4

That is how i would answer it

Answer 5

and what to do after i got "q" ?

Answer 6

you need to find a conversion factor that brings you from kj to cal

Answer 7

ok so...my answer right now should be in kj, and i have to convert that to J first...then convert from J to Cal correct?

Answer 8

nvm i just found out that 1 kj = .2390 cal

Answer 9

did they give you the conversion factors to do that?

Answer 10

they didn't

Answer 11

2626 Cal <-- sounds right ?

Answer 12

(10988.2)(.2390) = 2626

Answer 13

yea looks right to me however if they have different conversion factors or even a different periodic table our answers are going to differ slightly

Answer 14

you mean this?
1 Cal = 1000 cal = 4.184 kJ

Answer 15

yes that

Answer 16

uh oh...

Answer 17

how many kj did you get?

Answer 18

i got 10988 kj

Answer 19

\[10988 kj (\frac{1 Cal}{4.184kj})=\]

Answer 20

that still get me 2626.30

Answer 21

so it's the samething as multiply by .2930 then... :D

Answer 22

just trust me and always use the conversion factors that are given. Sometimes you will get slightly off looking up other conversion factors because the number could be more or less exact. the periodic table can behave in the same way and because you are doing this on a computer program it's not going to understand why you are coming up with a different answer than it is

Answer 23

know what i mean?

Answer 24

yeah i'll keep that in mind thanks :D

Answer 25

hmmm its wrong ^^!

Answer 26

maybe that 5 grams have something to do with it

Answer 27

" how many nutritional Calories are there per gram of the candy?"
2626/5 = 525.2 maybe ?

Answer 28

yea try that

Answer 29

omg still wrong lol...wtf I'm gonna go crazy cuz of this x_X

Answer 30

I would write all the chemistry down and take it to the teacher tomorrow because i'm pretty sure we have been right

Answer 31

but check your sig figs

Answer 32

tomorrow is saturday lol :D

Answer 33

good point, do you have another shot at this question? if so put in 525.500 Cal

Answer 34

hmm still wrong :(

Answer 35

it give some explanation:
First, use the temperature change and the heat capacity of the calorimeter to calculate the amount of heat produced in kilojoules. Then convert to Calories. Finally, divide your answer by the mass of candy burned to express the energy in Calories per gram.

Answer 36

we did that

Answer 37

divide by mass of candy burned ? where is that coming from?

Answer 38

wth =.=

Answer 39

try 525.20 Cal

Answer 40

unless you are out of chances

Answer 41

i don't think sig fig is necessary in this case

Answer 42

cuz the other problem i didn't do sig fig either and i got them right...this problem just weird..

Answer 43

well we did everything the hints told us to do

Answer 44

ya..wtf.. if i miss a sig fig, it would tell me to fix it..but it didn't say anything about sig fig so i guess that's not it :D

Answer 45

oh well..i gtg now, thanks for the help zbay
cya later!

Answer 46

sorry i couldn't be more help