slimshady45
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WILL GIVE BRAINLIEST 40 PTS!!!!

You place a bottle containing 2.6 Liters of mineral water at 25*C into a refrigerator to cool to 4*C. Remember to show work when necessary.
a. How many kJ of heat are lost by the water?
b. How many kJ of heat are absorbed by the refrigerator?
c. What assumptions did you make in your calculations?

Respuesta :

XRZ

a) and b) will be the same (assuming but "absorbed by the refrigerator" they mean increasing the temperature into the refrigerator to be removed by its action as a heat pump).

The first thing to determine is the temperature drop.  You know that after a long time the temperature of the bottle will be 7°C.  That makes ΔT = 25.0 - 7.0 = 18.0 °C = 18.0 °K.

You also know that 2 litres of water will weigh approximately 2 kilograms (since the density of water is 1kg/L) or 2000 g.

The heat capacity shows the relationship between temperature, mass and energy.  For water (at 25°C) this is 4.1813 J/g.°K. [1].

Using the equation C = Q/ΔT [2].  Therefore, Q = CΔT = 4.1813 (J/g.°K) * 18.0 (°K) ~ 75.26 (J/g).

You know you have 2000 grams of water so the amount of heat energy = 75.26 * 2000 (J) ~ 150,500 J or taking this to 3 significant figures and changing to kilojoules approximately 151 kJ.

Enjoy :)

joseaaronlara

Answer:

The answer to your question is below

Explanation:

data

volume = 2.6 l

temperature 1 = 25°C

temperature 2 = 4°C

density = 1 g/ml

specific heat = 4.186 J/g

Process

1.- Convert volume to milliliters

         1000 ml --------------- 1 l

             x         -------------- 2.6 l

             x = (2.6 x 1000)/1

             x = 2600 ml

2.- Calculate the mass of water

mass = density x volume

         = 1 x 2600

         = 2600 g

3.- Calculate the heat (Q)

Formula

           Q = mC(T2 - T1

-Substitution

            Q = (2600)(4.186)(4 - 25)

            Q = (2600)(4.186)(-21)

            Q = -228555.6 J  or - 228.6 kJ

a)     Heat lost = -228.6 kJ

b)     Heat absorbed = 228.6 kJ

c)     The assumptions I made were the specific heat of water, the density of water, lost of heat is negative and absorption of heat is positive.

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