There are four F atoms on the products side.
Since two more F atoms are required on the reactant side, you multiply the number of F2 molecules by two.
So 2 should be placed in front of F2
5 moles of H2
..............
The purpose of using distilled water in the cuvette of the spectrophotometer is to calibrate the instrument. It is generally considered that distilled water shows zero absorbance and 100 % transmittance. So, to zero out the absorbance of compounds other than the analyte being determined, distilled water is used as a blank.
If the unknown being determined is prepared using ethanol as the base solution, the blank used must be ethanol. This is because absorbance if any from the solvent, ethanol must be zeroed out as when the measurement of the actual unknown is being made, the absorbance of the solvent does not interfere.
Sodium Diacetate is a compound with the formula of NaH2. it is a salt of acetic acid. it is a colorless liquid that is used in seasonings and as an antimicrobial agent.
In the first situation: the mechanism of covection is the main form of heat transfer when warm air from a heater moves around and upward.
In the case of the metal pan the mechanism of heat transfer is conduction.
In the case of sunburn the mechanism is radiation.
In the case of an ice cube melting in a hand, conduction is the most important mechanism.
