Question

Duncan knows that it takes 36400cal of energy to heat a pint of water from room temperature to boiling. However, Duncan has prepared ramen noodles so many times he does not need to measure the water carefully. If he happens to heat 0.600pint of room-temperature water, how many kilojoules of heat energy will have been absorbed by the water at the moment it begins to boil?
Express your answer numerically in kilojoules.

Answer 1

Hmm, looks like a proportion. The new amount of energy is 0.600 times 36.400 kJ/pint

Answer 2

21.84

Answer 3

Unless I'm missing something, I think it is just that simple.
Though, for the sake of significant figures, I'd round to 21.8 kJ

Answer 4

do you have any idea carlos

Answer 5

Oh, woops, forgot to convert calories to joules...
Derp

Answer 6

Sorry, I was missing something.

Answer 7

so 21.8 is the calories and we convert to kilojoules

Answer 8

21.84 is kilocalories because already divided by 1000

Answer 9

It is not right.
If you need 36400 cal for 1 pint, for 0.6 pints yo need 0.6x36400=21840 cal=21.840 Kcal Now you need to convert Kcal to Kjoules: 1Kcal=4.1868 KJoules, then the solution is: 91.44 KJoules

Answer 10

yes that is what i got

Answer 11

thansk carlos

Answer 12

welcome

Answer 13

can you do one more

Answer 14

shoot

Answer 15

water (3110g ) is heated until it just begins to boil. If the water absorbs 5.01×105J of heat in the process, what was the initial temperature of the water?

Answer 16

i dont get this one at all

Answer 17

do you get it

Answer 18

\[Q=m·c·\Delta T\] We know it is heated until it boils, then \[\Delta T=100-T_0\] and \[c=4.18 KJ·Kg^{-1}·ºC^{-1}\]\[100-T_0=\frac{ 5.01·10^2 }{ 4.18·3.11 }=38.5 \rightarrow T_0=100-38.5=61.5\]in Celsius
Note that I have converted gr to Kgr and Joules to KJoules to match the constant "c" units

Answer 19

Note also that by definition: 1Kcal increases the temperature of 1 liter of water in 1 Degree Celsius. Converting 1 Kcal = 4.18KJ you get the constant I have given you

Answer 20

@toxicsugar22 solution is ready

Answer 21

ok

Answer 22

so 61.5 is the solution

Answer 23

you made theis problem so easy

Answer 24

Can you assess the solution?

Answer 25

yes so is 61.5 the answer

Answer 26

so we got it right. Its been more than 30 years I have not solved problems of Thermodynamics

Answer 27

thanks you you are the best tutor ever

Answer 28

you explain everthing so simply

Answer 29

not at all. There are very good people around here, really knowledgeable

Answer 30

UP NOPE IT WAS NOT RIGHT

Answer 31

The problem was easy itself. Sometimes I become entangled in my own explanations

Answer 32

i put it in my homeowork

Answer 33

and it says it not right

Answer 34

Hoe many decimal places youve got to give?

Answer 35

it says Enter your answer using dimensions of temperature

Answer 36

decimals are fine

Answer 37

I see no other solution:

1 calory increases 1 cc of water (1g) by one degree celsius. 1 Kcal increase 1C in one liter. The rest is easy

Answer 38

like how so was it right 61.5

Answer 39

and then we hoave to add hte units

Answer 40

Exat solution is: 61.4609456 C that I have rounded up to 1 decimal place 61.5

Answer 41

ok and the units

Answer 42

Unites are degrees celsius

Answer 43

Maybe you have to put 61.5C

Answer 44

i did

Answer 45

and did not work?

Answer 46

NO

Answer 47

MAYBE IT IS RIGHT BUT I DONT KNOW WHAY THEY ARE COUNTING IT AS WRONG

Answer 48

NO 61.5 WAS CORECT SORRY

Answer 49

FORGOT TO PUT DEGREE SIGN

Answer 50

oops!