The equation below represents a chemical reaction at 1 atm and 298 K.

Identify the change in energy that occurs in order to break the bonds in the hydrogen molecules.

2H2 (g) + O2 (g) --> 2H2) (g)

1. Endothermic and absorbed

2. Exothermic and released

3.Endothermic and released

4.Exothermic and absorbed

Aluminum–lithium (al-li) alloys have been developed by the aircraft industry to reduce the weight and improve the performance of its aircraft. a commercial aircraft skin material having a density of 2.47 g/cm3 is desired. compute the concentration of li (in wt%) that is required.

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size

In a reaction equation, where are the products located? a.) above the arrow b.) to the right of the arrow c.) to the left of the arrow d.) below the arrow