A teacher has found two white powders on a desk in the chemistry laboratory. she wants to test to see if they are pure substances, so she measures the melting points. substance X melts at 122 and substance Y melts between 87 and 93. explain which one is a pure substance

The difference between the atomic number of an element and the element’s atomic mass is the number of ions.

Which statement is usually true about the relationship between activation energy and reaction rates? low activation energy barriers result in low rates. high activation energy barriers result in low rates. low activation energy barriers result in no reaction. high activation energy barriers result in no reaction.

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?