Why must reagent bottles be closed when not in use?

A sample of a white solid contains 0.212 g of magnesium and 0.140 g oxygen. What is the empirical formula of this compound?

In the reaction Mg (s) + 2HCl (aq) → H2 (g) + MgCl2 (aq), how many moles of hydrogen gas will be produced from 250.0 milliliters of a 3.0 M HCl in an excess of Mg? 0.75 moles 0.38 moles 3.0 moles 1.5 moles

Which list of elements contain a metal, metalloid, nonmetal, and a noble gas

A 2.00 L container of nitrogen has a pressure of 3.2 atm. What volume would the container be at if the pressure decreased to 1.00 atm

You want to determine the concentration of a liquid solute dissolved in a liquid solvent. Which of the following would be the best to use?

Given the following information, calculate the mass for B-11. B-10 has a natural abundance of 19.9 percent, while B-11 has a natural abundance of 80.1 percent. The mass of B-10 is 10.013 amu.

How many moles of oxygen react with 0.23 moles of NH3

How many moles of carbon do you have in 100 quadrillion carbon atoms? report answer to 2 sig figs

A small 15 kilogram canoe is floating downriver at a speed of 4 m/s. What is the canoe's kinetic energy?

Liquid water is heated until it boils and becomes water gas. Which statement is true about the water?