Student Name Course/Section Date 4-2-18 Instructor PRE-LAB ASSIGNMENT L. A mixtu

Question

Student Name Course/Section Date 4-2-18 Instructor PRE-LAB ASSIGNMENT L. A mixture of KCI and KCIO, has a mass of 2.565 grams. The mixture KCIOs is decomposed. After cooling, its mass is found to be 1.987 grams. the following calculations and show all work is heated and the Perform each of (a) Calculate the mass of oxygen lost from the mixture. Q. 565 - 1.9870.518 1os oF Oz (b) Calculate the number of moles of O, lost from the mixture. O. 5780 ÷3a, mol =00180625 mol (c) Calculate the number of moles of KCIO; in the original mixture. 0.0036 mol /6xa 001 a mol hCIO (d) Calculate the mass of KCIO; in the original mixture. 1.981-0.5785-1.409ghC103 (e) Calculate the percentage of KCIO; in the original mixture 1.4 ta | 3.565

Explanation / Answer

1 .(a) If the test tube is not heated long enough, then all the KClO3 will not decompose and mass lost due to oxygen will be less than actual. So, mass percent of KClO3 (calculated) will be less than actual value.

(b) The mixture which is lost contains both KCl and KClO3. But it happens after weighing. So there will be error in calculating the mass of lost O2 and it will be less than actual value. So, the calulated mass of KClO3 ( based on the mass of lost O2) will be less than actual and mass percent of KClO3 (calculated) will be less than actual value.

(c) If the test tube contains some moisture, it mixes with the mixture and actual mass (recorded) is more than the actual mass of the mixture. The calculated mass of KClO3 will be less than actual value.

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