When sodium bicarbonate and acetic acid are combined in a beaker and allowed to
run to completion, a small amount of sodium bicarbonate remains unreacted at the
bottom of the beaker at the end of the experiment. This means that the sodium
bicarbonate is the
in this experiment.
limiting reactant
O excess reactant
O product
catalyst

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8