Questions (23)-(26) refer to the liquid-solid phase diagram shown below 23.) A m
ID: 557813 • Letter: Q
Question
Questions (23)-(26) refer to the liquid-solid phase diagram shown below 23.) A mixture at a exists as (a.) A liquiod (b.) Two solids (c.) A liquid and a solid (d.) A liquid and two solids solic 0 15 24.) If the mixture is cooled to Mole faction of B. a, the mixture exists as (a.) A liquiod (b.) Two solids (c.) A liquid and a solid (d.) A liquid and two solids 25.) Suppose you have two solutions (I and II) of A and B mixture. Solution I has a mole fraction ofx,-0.3, and in solution II x, -0.8. If both solutions are subject to cooling, in which of the two solutions does A crystallize out first? (a.) A crystallizes out at the same time from solution I as from solution II (b.) A crystallizes first form solution I (c.) A crystallizes first form solution II (d.) A does not crystallize form either of the two solutions 26.) Which of the following is most likely to be the cooling curve for a solution with composition (lowest meltir point)?Explanation / Answer
1. A liquid
because the temperature at A1 is more ,hence making the mixture liquid.
2. A liquid and two solids
because at A3 the mixture stands on the line of solid and liquid as per the provided temperature and it is called eutectic mixture of A and B.
3. A crystallizes first from solution 1 as it has less mole fraction than soln 2.
beacause the freezing is directly proportional to mole fraction.
4. graph C
As we cool pure liquid A nothing much happens until we reach the melting point of A. At the melting point of A the curve takes a "halt." That is, the temperature holds constant until all of the liquid has been converted into solid. The temperature stays constant for a period of time because our cooling mechanism, whatever it is has to remove the heat of fusion which is given off when the liquid is convert into solid. When all of the liquid has been converted to solid we begin cooling the solid and nothing else.
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