Astudent is preparing to perform a series of calorimetry experiments. she first wishes to determine the calorimeter constant (ccal) for her coffee cup calorimeter. she pours a 50.0 ml sample of water at 345 k into the calorimeter containing a 50.0 ml sample of water at 298 k. she carefully records the final temperature of the water as 317 k. what is the value of ccal for the calorimeter? a student is preparing to perform a series of calorimetry experiments. she first wishes to determine the calorimeter constant (ccal) for her coffee cup calorimeter. she pours a 50.0 ml sample of water at 345 k into the calorimeter containing a 50.0 ml sample of water at 298 k. she carefully records the final temperature of the water as 317 k. what is the value of ccal for the calorimeter? 99 j/k 21 j/k 76 j/k 28 j/k 19 j/k

Calorimetry is the measurement technique, in which heat of the chemical reactions and heat capacity is measured. The value of Ccal for the calorimeter is 99 J/K.

According to the first law of thermodynamics, the energy cannot be created nor be destroyed. It can be transferred from one form to another.

Such as:

Also, from the formula, it can be calculated as:

Given that,

Now, substituting the values, heat released by the water will be:

Similarly, heat absorbed by the cold water will be:

Now, the overall heat absorbed by the calorimeter will be equal to:

The value of Ccal will be:

Therefore, the Ccal for the calorimeter will be equal to approximately 99 J/K.

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Explanation:

1) First law of thermodynamic (energy balance)

2) Energy change of each substance:

Heat released or absorbed = mass × Specific heat × change in temperature

       Heat₁ = 49.9 g × 1 cal / g°C × (345 K - 317 K) = 49.9 g × 1 cal / g°C × (28K)

       Heat₂ = 49.9 g × 1 cal / g°C × (317 K - 298 K) = 49.9 g × 1 cal / g°C × (19K)

       Heat₃ = Ccal × (317 K - 298 K) = Ccal × (19K)

4) Balance

49.9 g × 1 cal / g°C × (28 K) = 49.9 g × 1 cal / g°C × (19 K) + Ccal × (19 K)

Ccal = [49.9 g × 1 cal / g°C × (28 K) - 49.9 g × 1 cal / g°C × (19 K) ] / 19K

Ccal = 23.6 cal/ K

       23.6 cal / K × 4.18 J / cal = 98.6 J/K

Which rounded to 2 signficant figures leads to 99 J/k, which is the first choice.

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water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.