Physics, Chemistry & Maths Glossary

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H

Heisenberg Uncertainty Principle

It would be impossible to make accurate measurements of certain pairs of properties, since any technique used for measuring one of them will disturb the system and will cause the measurement of the other one to be imprecise. For instance the method used to measure the position of the particle will result in an uncertainty in the precision of the measurement of the momentum of the particle.

Hemiacetal

It is the product of nucleophilic addition of an aldehyde or ketone to an alcohol. 1 molecule of alcohol adds to 1 molecule of aldehyde or ketone to yield hemiacetal.

Formula: RCR'(OR")(OH). OR" has been supplied by the alcohol whereas R and R' originally belong to the aldehyde or ketone. If it is an aldehyde, then one of the two i.e. R or R' must be H.

PS: Hemi means half. Hemiketal name is no longer in use by IUPAC, it was used in the past to distinguish between aldehydes & ketones.

Hydrocarbon Combustion

\(C_x H_y + (x + {y \over 4})O_2 \to xCO_2 + {y \over 2}H_2 O\)