1. why does putting baking soda on a fire put it out? a. the baking soda cools the fire off so it can’t burn. b. co2 gas is produced reducing the amount of heat. c. the fuel is covered and not available to the fire. d. co2 gas is produced cutting off the flow of oxygen. 2. why does baking bread require a constant input of heat from the oven? a. it is a physical reaction. b. it is an endothermic reaction. c. it is a chemical reaction. d. it is an exothermic reaction.

Hot air balloons float in the air because of the difference in density between cold and hot air. in this problem, you will estimate the minimum temperature the gas inside the balloon needs to be, for it to take off. to do this, use the following variables and make these assumptions: the combined weight of the pilot basket together with that of the balloon fabric and other equipment is w. the volume of the hot air inside the balloon when it is inflated is v. the absolute temperature of the hot air at the bottom of the balloon is th (where th> tc). the absolute temperature of the cold air outside the balloon is tc and its density is ďc. the balloon is open at the bottom, so that the pressure inside and outside the balloon is the same. as always, treat air as an ideal gas. use g for the magnitude of the acceleration due to gravity.

Think about how you can use le chatelier’s principle to find possible solutions to the design problem. describe at least two ways to increase the yield (amount) of ammonia based on this principle.

What overall charge must all compounds have