For some jobs, “good enough” is good enough. That’s sometimes true in chemistry. More often, though, careful planning, calculations, measurement, and laboratory work are necessary to get the desired result. Imagine two tasks that would involve a chemical reaction of some sort. For one, measurement is not all that critical. For the other, careful stoichiometry and laboratory process is essential. Identify and describe two tasks (projects, operations, devices, etc.) that differ in this way.

Drag each label to the correct location on the chart. classify each reaction as endothermic or exothermic.

Compare and contrast physical changes with chemical changes.

7. using your knowledge of colligative properties explain whether sodium chloride or calcium chloride would be a more effective substance to melt the ice on a slick sidewalk. use 3 – 4 sentences in your explanation. 8. when a 2.5 mol of sugar (c12h22o11) are added to a certain amount of water the boiling point is raised by 1 celsius degree. if 2.5 mol of aluminum nitrate is added to the same amount of water, by how much will the boiling point be changed? show all calculations leading to your answer or use 3 – 4 sentences to explain your answer. 9. if 5.40 kcal of heat is added to 1.00 kg of water at 100⁰c, how much steam at 100⁰c is produced? show all calculations leading to an answer. 10. the freezing of water at 0⁰c can be represented as follows: h2o (l) ↔ h2o(s) the density of liquid water is 1.00 g/cm3. the density of ice is 0.92 g/cm3. in 3 – 4 sentences explain why applying pressure causes ice to melt.