When cooking frozen cheese ravioli, the directions say to put the 255 grams of f

Question

When cooking frozen cheese ravioli, the directions say to put the 255 grams of filled pasta into 3 quarts of boiling water. Why should you use 3 quarts when 1 quart would easily cover them all?  

Suppose they are in the freezer at - 40 °C. You may consider the ravioli to have a specific heat of 0.4 cal/gam-°C both when frozen and when in water.

(A) By how much does the temperature of the 3 quarts of water drop when you add the frozen ravioli?

(B) How much would the water temperature drop if you used only 1 quart?

(C) So what is the answer? Why do they ask for 3 quarts?

Explanation / Answer

The final temperatures of both ravioli and water are say t.

Heat lost by water = heat gained by ravioli

So 3 quarts =3 * 946gms =2838gms,specific heat of water is 1 cal/gm

So 2838*1*t(water) = 255*0.4*(t)(ravioli)

Boiling water has initial temperature of 100°C

So 2838*(100-t) =102*(t-(-40))

Solving for t we get 2782-27.82t =t +40

t = 2742/28.82

T =95.14°C

If we use 1 quart then it is 946 grams

946(100-t) =102*(t+40)

T = 887/10.27= 86.3°C

To cook ravioli we need more than 90°C

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