The dissolution of CaCl(s) in water is exothermic, with ΔHsoln= -...

Question

The dissolution of CaCl(s) in water is exothermic, with ΔHsoln= - 81.3 kJ>mol. If you were to prepare a 1.00 m 
solution of CaCl2 beginning with water at 25.0 °C, what would the final temperature of the solution be in °C? Assume that the specific heats of both pure H2O and the solution are the same, 4.18 J>1K g2.

Accepted Answer

Hello everyone today. We are being asked the following question. A .55 Allow solution of sodium iodide is prepared at 25°C, determine the final temperature of the solution. Given that the specific heat capacity of the solution is the same as water. And The entropy change of the solution of sodium iodide is negative. 7.53 kg per mole. So we are being given different variables. Here we are being given A . moral which if we write that out um allow is in units. So Malala is in units of moles per kilogram. So this would be equal to .55 moles of our sodium iodide per one kg of water. Secondly, we want to find the mass of the solution. So we want to find the mass of the solution and so that's going to be equal to our one kg of water. And when we convert that to grams, that's going to be 10 to the third grams is equal to one kg because we want this in units of grams ultimately. And then we're gonna add that to our molds that we have. So we have the mass of the solution that would be comprised of the water and the mass of the sodium iodide. And so that is going to be . malls there multiply By the molar mass of that which would be 149 g per mole. The molar mass of sodium iodide. That is when our units cancel out and we put this into our calculator, we get an answer of 1,082. g. So we're gonna hold on to this number for later. Our 3rd step is to calculate the heat of our solution. And so that can be done using the following formula here. So the heat of our reaction, you could do the entropy change of our solution or the opposite or negative for our moles of our sodium iodide. And so that's going to include a negative 7.53 kg per mole per the question. And we're gonna multiply this by the number of moles that we have for sodium iodine, which is .55 moles. Ultimately we're going to end up with 4 -4.14 kila jewels which then needs to be converted to regular jules. So that's gonna be 4.14 kg joules times 1000 jewels is equal to one killer jewel. And this is gonna give us negative 4,141.5 jewels. So now that we have the heat of our solution, we have our heat of our reaction times equal to the negative or the opposite heat of our solution equal to negative M cat or a mass times specific heat capacity times are changing temperature. So the heat of our reaction we calculated was negative 4,141.5 jewels were gonna equal to the mass that we sold for for our solution. And so that's going to be -1082.44 g Times specific heat capacity of water, which is 4.18 jewels programs at Times C. And then we don't have a final temperature, But we do have an initial temperature of 25°C. And when we calculate this, we end up with a final temperature of 25.9°C as our final answer. And with that we have answered the question overall. I hope that this helped and until next time.

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