Chemical Analysis

• What is formulations?

  mixture that has been designed as a useful product
• What is a pure susbstance?

  a pure substance is a single element or compound, not mixed with any other substance.
• What is an example of a formulation?

  -cleaning agents

  -paints

  -alloys
• How are formulations made?


  Formulations are made by mixing the components in carefully measured quantities to ensure that the product has the required properties
• What is chromotography?

  ● Used to separate mixtures and give information to help identify substances

  ● Involves a stationary phase and a mobile phase

  ● Separation depends on the distribution of substances between the phase
• What is a retention factor?

  The ratio of the distance moved by a compound (centre of spot from origin) to the distance moved by the solvent can be expressed as its Rf value
• How is retention factors calculated?

  Rf = distance moved by substance/distance moved by solvent
• What are the uses of chromotography?

  -detect bombs

  -fingerprinting

  -identify drugs and alcohol
• What is the test for Oxygen?

  ● Uses a glowing splint inserted into a test tube of the gas

  Splint relights in oxygen
• What is the test for hydrogen?

  ● Use a burning splint held at the open end of a test tube of the gas

  -Creates a ‘squeaky pop’ sound (hydrogen burns rapidly)
• What is the test for carbon dioxide?

  ● Bubble the gas through the limewater (calcium hydroxide (aq))

  • it will turn milky (cloudy
• How can we tell if a sample is impure?

  -melt/boil it and compare to known data.If it dosent match its impure eg water melts at 0 degress and boil at 100 degrees

  -do chromatography(one spot only)
• Explain how chromoatography separates substances?

  -the samples dissolve in the mobile phase (solvent)

  -they are carried up in the stationary phase (paper)

  -they are deposited
• what errors can be done in chromotography set up?

  -base line below solvent line

  -wrong solvent solution

  -base line in pen
• Chromatography practical

  1) take a piece of chromatography paper and draw a pencil line about 1-2 c, up from the bottom with a ruler

  2)under the line note down the samples

  3)then spot the sample on the base line above the label

  4)place the paper onto a beaker containing solvent.The solvent must be below the base line

  5)leave the beaker untouched,so the sample can separate

  6)once the solvent line is near the top,take the paper out and let it dry

  7)then calculate the retention factor =distance moved by spot/distance moved by solvent(always under 1)
• water purification practical

  -added universal indicator to different water samples to find ph

  -weighed a watch glass,the place a sample of water on top and evaporate it

  -reweigh with impurities left to identify which sample of water was most pure(the one with least stuff on)

  -also test a water sample from distillation which was pure