What do parentheses around a group of atoms in a chemical formula indicate?

8. A student performing an investigation of chemical reactions mixes two aqueous solutions and observes a change in color.

The half-life of radium-226 is 1600 years. How many grams of a 0.25 g sample will remain after 4800 years?

Who first proposed the idea of an atom?

At what temperature will the following reaction happen spontaneously, given that ΔH = 8.91*103 J/mol and ΔS = - 219.20 J/mol·K? CaSO4 (s) + 2HCl (g) → CaCl2 (s) + H2SO4 (l)

During an experiment, distilled water was placed in a sealed container and the container was heated gradually. Describe this system when it reaches phase equilibrium.

Which statement is true according to the kinetic theory? 1. Moles of different gases with the same mas and temperature always have the same average density. 2.

A substance with a pH of 9 has A) no H30 + ions or OH - ions. B) more H30 + ions than OH - ions. C) more OH - ions than H30 + ions. D) the same number of H30 + ions as it does OH - ions.

Consider the following quantities used in thermodynamics: E, H, q, w, S, G. How many of them are state functions? a. 2 b. 0 c. 3 d. 1 e. 4

What are some good problem statements

A 5.00L reaction vessel is filled with 1.00mol of H2, 1.00mol of I2, and 2.50mol of HI. If equilibrium constant for the reaction is 129 at 500k, what are the equilibrium concentrations of all species?