25.0 cm3 of a solution of sodium hydroxide required 18.8 cm3 of 0.0500 mol/dm3 H2SO4

H2SO4+2NaOH—> Na2SO4+ 2H2O

1) find the concentration of the sodium hydroxide solution in mol/dm-3

2) find the concentration of sodium hydroxide solution in g/dm3

Silver tarnishes as silver metal reacts with hydrogen sulfide, h2s, in the air. in this reaction, dark silver sulfide, au2s, covers the surface of silver. when silver is polished, this coating of silver sulfide can be removed from the surface. this makes the silver shiny again. enter the coefficients that balance the tarnishing reaction equation. (type 1 for no coefficient.)

Compare and contrast physical changes with chemical changes.

Enzymes affect the reactions in living cells by changing the