How is enthalpy used to predict whether a reaction is endothermic or exothermic?

Which type of precipitation would most likely form when the surface air temperature is slightly below freezing and the air temperature increases as you move upward away from the ground?

You are attempting to recrystallize a crude product mixture. you add the appropriate amount of hot solvent and are allowing the solution to slowly cool to room temperature. however, at room temperature no crystals have appeared, which of the following methods should be used to induce crystallization? choose all correct answers. a) place the flask in an ice bath. b) swirl the contents of the flask. c) add a small seed crystal of the desired product. d) scratch the inside of the glassware using a stir rod. it can be multiple choices

What two factors can affect the properties of a hydrocarbon? a. the number of its carbon atoms and the number of single bonds b. the number of its carbon atoms and the arrangement of its atoms c. the arrangement of its atoms and the number of its double bonds