separating + purifying - exam qs

Created by

amisha

Cards (13)

Chromatography - Give a change that could be made to the experiment to obtain an Rf value for the insoluble colouring.
Use a different solvent
Describe how oxygen and nitrogen are obtained from liquid air by fractional distillation:
Liquid air enters the fractionating column. The liquid air is boiled and nitrogen has a lower boiling point it can be collected from the top of the column while oxygen is collected from the bottom.
Give an example of a soluble and insoluble substance in water:
Aluminium nitrate and lead sulphate
What is the appearance of barium sulphate?
It is a white precipitate or powder
How can a pure dry sample of solid carbonate be obtained from sodium carbonate and lead nitrate?
Mix sodium carbonate and lead nitrate. Filter out the precipitate and then leave it to dry.
What colour will copper sulphate turn in flame test?
Blue green
Is ammonium chloride soluble or insoluble?
Soluble
Is lithium sulphate soluble or insoluble?
Soluble
Is magnesium carbonate soluble or insoluble?
Insoluble
Hexane and water are immiscible. Describe how separate samples of hexane and water can be obtained of hexane and water?
Use separating funnel and allow the liquids to separate
Methane is a typical simple molecular, covalent compound. What is the property of methane?
Low boiling point, low melting point, not good at conducting electricity
Graphite is a form of the element carbon. Graphite is a giant molecular covalent substance. Use the structure and bonding in graphite to explain why it can be used as a lubricant and as a conductor of electricity:
Carbon atoms are joined together by covalent bonds and each atom is bonded to 3 other carbon atoms in a hexagonal arrangement. There are weak forces between layers and they can slide over each other making it a good lubricant. There are free electrons between layers that can move and carry current hence the conduction of electricity.
Give a use of graphite due to its electric conduction?
Electrodes