15.0 mL of 0.50 M HCl is added to a 100.-mL sample of 0.314 M HNO, (Ka for
HNO2,=4.0 x 10-4). What is the equilibrium concentration of No2 ions?

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.)

Which of the following is true about the speed of light? it depends on the wavelength.

What is the mass of 0.750 mole of aluminum oxide, al2o3?