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Biker

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## Homework Statement

The following chart shows the temperature before and after Melting Ice. (A, B) have the same amount of water. If the heat required to fuse both cube are equal. The ratio between the two cubes mass:

Cup Before After

A 25 21

B 25 23

A :B

1) 2: 1

2) 1:1

3) 1:2

4) 1: 4

## Homework Equations

q = M C dT

dH = n (molar dH)

## The Attempt at a Solution

I am going to assume both ice are at exactly 0 C and they only calculated until the [/B]

This question came in an exam two years ago and it is confusing me a lot.

"Heat required to fuse both cubes are equal" Which implies that the two cubes must have the same mass.

But there is a difference in the temperature so the mass must not be the same

I used this equation.

n (molar dH) = M(water) C dT

for both a and b which means

that The ice cube placed in A has twice the mass of ice cube placed in B.

They chosed 3 as an answer by the following way

q = m(a) c dT

q = m(b) c dT

and by the statement of "Heat required to fuse both cubes are equal" you get Mb:Ma 2:1

But there is a couple of problems here.

First if we assume that they placed it at 0 C and then left both cups until they reach equilibrium. You dT is not a common factor between the ice and water so you can't use this equation.. Secondly C isn't the same you can make an approximation to calculate it which shows that c is not the same. So The question is poorly made.A real solution would make an expression of the heat required to fuse it to water then raise that amount of water(Ice after melted) temperature to the equilibrium temperature. Which would be close to 1:1 because the amount of heat needed to raise to equilibrium temperature is negligible

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