Separating Mixtures Flashcards
What are the differences between compounds and elements?
Compounds are made up of two or more different elements (chemically bonded), but elements are made up of only one type of atom (chemically bonded)
What are the differences between a compound and a mixture?
A compound has chemically bonded elements, whereas, mixtures are just two substances mixed together, not chemically bonded
What are features of metals?
- hard
- high electrical and thermal conductivity
- high melting and boiling points
What are features of non-metals?
- softer than metals
- many times colorful
- react with hydrogen and form stable hydrides
What is used to measure the volume of a liquid or gas?
burette
What is used to measure weight and mass?
weight - newtonmeter
mass - scale
What is a solution? What about solvent and solutes?
A solution is a uniform mixture of two substances, formed by a solute and a solvent. The solute is the substance dissolved and the solvent is the substance the solute was dissolved in.
What are two ways to separate a solid from a liquid? How do they work?
Filtration: solution is placed on filter paper, which is on funnel. The solid will not go through the filter paper, but the liquid will. The liquid is called the filtrate and the solid is called the residue
Centrifugation: a centrifuge is used to spin the solution very quickly so that the solid particles will fall to the bottom.
What are two ways to separate a solid from its solution? How do they work?
Evaporation: the solution is heated up so that the liquid evaporates and leaves the solid behind.
Crystallisation: a solution is heated up to leave the solid behind but this time instead the solid forms a crystal
What is distillation? How does it work?
Distillation is the separation process which removes a solvent from its solution.
The solution is heated up so that the solvent will evaporate. The flask is connected to a condenser tube which is surrounded by cold water and turns the evaporated gas a liquid again, to be placed in a different flask.
What is fractional distillation?
Fractional distillation is a separating process which separates two or more liquids from a mixture. It works by heating up the solution, which will make one of the liquids evaporate. When the liquid evaporates, it goes through the fractionating column which helps the separation to occur smoothly. Then it’ll be condensed again into a liquid by a condenser, thus separating that liquid from the solution. For this process to work, the liquids must have different boiling points.
What is chromatography?
Chromatography is a process of finding out the different substances in a solution. It can be used to find the different colored substances in ink.
How do you find the Rf (retardation factor) in a chromatography experiment?
You divide the distance of centre of spot from start by the distance of the solvent front.
What does the Rf tell us?
If the Rf is closer to 0, it has a low affinity with the solvent.
If the Rf is closer to 1, it has a higher affinity with the solvent.
What is a locating agent in chromatography?
It is used to locate substances that do not have color in the experiment.
