What happens to the mass of a substance during a physical change?

A pure substance made of one kind of atom

How many molecules are in 9.8 moles of Ni?

What are the terms used to describe locations on a sand dune

A 100.0 g sample of water at 27.0°c is poured into a 70.3 g sample of water at 89.0°c. what will be the final temperature of the water?

Which of the following elements has two valence electrons?

The characteristic flame test colors of metal ions are due to atomic emission spectra. Duscuss the relationship between the absoption and emission of light and the factors responsible for flame test colors.

Should a bartender use ice and scoop directly from ice machine or use an ice holding device and scoop to make drinks and refill drinks from

What classification should this reaction have? 4Al + 3O2 → 2Al2O3

If you start with 100 grams of a radionuclide, how much will you have after two half-lives have passed?

Identify the spectator ions in the following complete ionic equation. 2k (aq) s2 - (aq) pb2 (aq) 2no-3 (aq) →pbs (s) 2k (aq) 2no-3 (aq) express your answers as ions separated by a comma.