Consider the chemical equations shown here. 2 equations. 1: 2 upper H subscript 2 (g) plus upper O subscript 2 (g) right arrow 2 upper H subscript 2 upper O (g). Delta H 1 equals negative 483.6 kilojoules divided by 2 equals negative 241.8 kilojoules per mole. 2: 3 upper O subscript 2 (g) right arrow 2 upper O subscript 3 (g). Delta H 2 equals 284.6 kilojoules divided by 2 equals 142.3 kilojoules per mole. What is the overall enthalpy of reaction for the equation shown below? 3 upper H subscript 2 (g) plus upper O subscript 3 (g) right arrow 3 upper H subscript 2 upper O (g). kJ

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.)

The ozone molecule o3 has a permanent dipole moment of 1.8×10−30 cm. although the molecule is very slightly bent-which is why it has a dipole moment-it can be modeled as a uniform rod of length 2.5×10−10 m with the dipole moment perpendicular to the axis of the rod. suppose an ozone molecule is in a 8000 n/c uniform electric field. in equilibrium, the dipole moment is aligned with the electric field. but if the molecule is rotated by a small angle and released, it will oscillate back and forth in simple harmonic motion.what is the frequency f of oscillation?

A4.86 g piece of metal was placed in a graduated cylinder containing 15.5 ml of water. the water level rose to 17.3 ml. what is the density of the metal. i need the steps of how to solve it to so i can use a formula to work out other problems.