What mineral is not scratched by a fingernail, but is scratched by a copper penny?

Using data from seismic waves, geologists have learned that earth’s interior is made up of several

Given the following at 25c calculate delta hf for hcn (g) at 25c. 2nh3 (g) +3o2 (g) + 2ch4 (g) > 2hcn (g) + 6h2o (g) delta h rxn= -870.8 kj. delta hf=-80.3 kj/mol for nh3 (g), -74.6 kj/mol for ch4, and -241.8 kj/mol for h2o (g)

Assume that 13.5 g solid aluminum (al) react with hcl to produce solid aluminum chloride (alcl3) salt and gaseous hydrogen (h2) at standard temperature and pressure.