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 2.42 g/cm3 is desired. compute the concentration of li (in wt%) that is required. the densities of aluminum and lithium are 2.71 and 0.534 g/cm3, respectively.

Which common material is an example of a polymer? (25 pts) a. steel b. plastic c. petroleum d. rubbing alcohol

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

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)