A pot on the stove contains 400 g of water at 20 degree C. An unknown mass of ic

Question

A pot on the stove contains 400 g of water at 20 degree C. An unknown mass of ice that is originally at -10 degree C is placed in an identical pot on the stove. Heat is then added to the two samples of water at precisely the same constant rate. Assume that this heat is transferred immediately to the ice or water (in other words, neglect the increase in temperature for the pot). We will also neglect evaporation. The ice melts and becomes water, and you observe that both samples of water reach 70.0 degree C at the same time. (a) How does the mass of the original piece of ice in the second pot compare to the mass of the water in the first pot? The mass of the ice is smaller than the mass of the water. The mass of the ice is larger than the mass of the water. The mass of the ice is the same as the mass of the water. There's not enough information to answer this question. (b) Which system will reach 80 degree C first? The first pot, which had the 20 degree C water in it at the beginning. The second pot, which had the ice in it at the beginning When the pots reach 70.0 degree C, they both contain water, so they will both reach 80 degree C at the same time. There's not enough information to answer this question. (c) Solve for the mass of the ice that was originally in the second pot. The specific heat of liquid water is 4186 J/(kg degree C), and of solid water is 2060 J/(kg degree C). The latent heat of fusion of water is 3.35 times 10^5 J/kg.

Explanation / Answer

(A) same heat is provided to both of the samples.

Q = m C deltaT

for ice deltaT is greater hence m will be smaller.

Ans: mass of is smaller then the mass of water.

(B) now both are at same temp.

and mass of ice is less so it will require less heat.

Ans: The second pot, which had the ice in it at the beginning.

(C) Q = 0.40 x 4186 x (70 - 20)

Q = 83720 J

For ice pot,

Q = (m x 2060 x 10) + (m x 3.35 x 10^5) + (m x 4186 x 70)

Q = 648620m = 83720

m = 0.129 kg Or 129 grams

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