2Na(s) + 2HCl(aq)
2 NaCl(aq) + H, (3)

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

he uptake of drugs from the intestine is often strongly influenced by diffusion. for example, consider a water-insoluble steroid for treating inflammation that is solubilized in aggregates of detergent molecules, called micelles. these micelles, aggregates of 80 soap molecules, have a molecular weight of 24,000, a diameter of 2.6 nm, and a charge of -27. the positively charge ions (counterions) in this system are na".