1: Write the positive and negative ions that result when the following compounds are dissolved in an aqueous solution: Compound:
1. Na2CO3(a)
2. FeBr3(aq)
3. Al2(SO4)3(aq)

2: Write word and formula equations for the reaction of sodium hydroxide, NaOH(aq) and phosphoric acid, H3PO4(aq). Word equation. Formula equation. Why does this reaction occur?

Which function is performed by earths atmosphere? a. ultraviolet rays are prevented from reaching the ozone layer. b. earths temperature is raised and moderated by trapping in heat c. charged particles from the sun are prevented from reaching earth. d. magnetic charges from space are prevented from reaching earths surface.

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.

7. what temperature is need to just dissolve 50 g of nh4cl in 75 g of water? '