Edexcel (9-1) Topic 2

Solids, Liquids and Gases are the three main states of matter. Which is the correct order of state changes?

Which of the following are the ways in which fresh water is sterilised?

Complete the following sentences about treating fresh water. In the United Kingdom (UK), rain provides water with low levels of dissolved substances (called [blank_start]fresh[blank_end] water) that collects in the ground and in lakes and rivers. To make this water potable, it must go through these steps: [blank_start]sedimentation[blank_end] - solids sink to the bottom and are removed [blank_start]filtration[blank_end] - fine particles like sand are removed sterilising - microbes are [blank_start]killed[blank_end]

Paper chromatography works because some of the coloured substances are better at dissolving in the liquid than they are at bonding with the paper, so they travel further [blank_start]up[blank_end] the paper.

[blank_start]Filtration[blank_end] is a method for separating an [blank_start]insoluble[blank_end] solid from a liquid. A mixture of liquid and solid is passed through filter paper into a flask below. The solid stays on the filter paper ([blank_start]residue[blank_end]), and the liquid passes through to the container below ([blank_start]filtrate[blank_end]). [blank_start]Crystallisation/evaporation[blank_end] is a method that separates a [blank_start]soluble[blank_end] solid from a liquid. A solution of liquid and dissolved solid is heated, causing the solvent to evaporate and leaves solid crystals behind. [blank_start]Simple distillation[blank_end] is a method for separating the [blank_start]solvent[blank_end] from a solution, leaving behind the solute. This method works because the solvent has a much lower boiling point than the dissolved solute. Heating the solution allows the solvent to evaporate, and then it passes through a condenser, where it is cooled and condensed into a separate container. The [blank_start]solute[blank_end] does not evaporate and so it stays behind. [blank_start]Fractional distillation[blank_end] is a method of separating multiple [blank_start]liquids[blank_end] from each other. The technique works in the same way as distillation, but on a much larger scale.

A pure substance is either a single element, or compound, that is not mixed with any other substance.

Calculate the Rf value of the red spot if it moved 7 cm, and the solvent moved 9 cm (2 d.p.). [blank_start]0.78[blank_end]

Paper chromatography consists of two stages: the [blank_start]stationary[blank_end] phase (a.k.a. the phase that doesn't move - this is the [blank_start]paper[blank_end]) the [blank_start]mobile[blank_end] phase (a.k.a. the phase that moves - this is the [blank_start]solvent[blank_end])