purity and formulations Flashcards
what’s a pure substance?
a chemically pure substance is a single element or compound.
how many substances does a chemically pure substance contain?
one substance
how’s purity worked out?
by looking at the melting and boiling points of samples.
examples of pure substances->
water, copper sulphate, glucose, oxygen gas and sodium choride.
what point do impurities lower?
the melting point and increase the range of temperatures at which the sample will melt.
what point do impurities increase?
the boiling point and increase the range of temperatures at which the sample will boil.
what are formulations?
mixtures of chemicals that are designed to create useful products
to ensure a formulation does what it’s supposed to each chemical component must be?.
present in a precisely measured quantity.
examples of formulations that we encounter in everyday life->
fuels, cleaning agents, metal alloys, medicines and fertilisers.
what’s chromatography?
a process that seperates a mixture into it’s different components.
2 phases of chromatography->
substances are picked up and carried by a mobile phase (liquid or gas).
the mobile phase then moves through a stationary phase (solid or viscous liquid.)
when does a substance move far?
if it’s attracted to the mobile phase.
when does a substance not move far?
if it’s more attracted to the stationary phase.
in chromatography, substances are picked up and carried by a mobile phase (liquid or gas)
which then moves through a stationary phase (solid or viscous liquid)
what are the two phases of chromatography?
mobile and stationary.
3 impacts of adding impurities to a sample->
decrease the melting point
increase the range of temperatures at which a sample will melt or boil
and increase the boiling point
What do we call mixtures of chemical components that are designed to create useful products?
formulations
How many chromatography spots are produced by pure samples, and why
The definition of a chemically pure substance is that it consists of only a single element or compound.
This means that pure samples will only ever produce 1 chromatography spot regardless of solvent identity.
stages of chromatography->
the substance is picked up by the mobile phase.
the mobile phase moves through the stationary phase.
in chromatography the number of spots produces by a mixture can vary depending on?..
which solvent is used
what reduces the sharpness of a melting point?
impurities
Which state of matter can a mobile phase in chromatography not be?
solid
The closer the experimentally recorded melting and boiling points are to those found in the databook, the ? a sample is.
the purer a sample is.
