7. Crude oil

Crude oil is a ___________________ found ______ in the Earth crust. It’s a ___________of different _________________, molecules made of ______________ and ___________. Some of _________________ in the mixture are very small – just a few ___________ joined together. Others are far more ____________ with many _________ forming long chain _______________. But as a mixture it’s _____________. The different_____________ need _________. The technique used is _____________. This simple ______________ is set up in a fume cupboard. ____________ wool stops the __________ spitting when it’s __________. ___________ is dropped into the _____________ of the tube. A collecting __________ is put in place. And the ______________ leveled with the side arm ___________ temperature. The ___________ step is to gently heat the ___________ by immersing the __________ into a hot ___________ bath. The ___________ with a lower __________ point begin to _____________ immediately. They’re ____________. So it’s safer not to _________ with a naked _________. As the vapor _________, it enters the side arm where it ________ and ________. This happens at about ___________. The ___________ which boil at this ___________ drip ___________ the side arm and form our first ___________. It’s a colorless ___________. The _____________ stays at around ____ until all the __________ with this ___________point ______________. The hydrocarbons left __________ aren’t _____ enough to _________. Their _______ point must be _______. Once the first _________ has been ________, it’s safe to ______ heating with a Bunsen. As the ______________ rises, other ______________ begin to boil. A new _________ is collected at about _____ Celsius. It’s slightly ________ in color. And so the _________ continues. By carefully__________ the oil and collecting the ________ which ________ at a number of different ____________, the many ________________ hydrocarbons in __________ can be _________. This is known as _____________ distillation. On a larger scale, a __________ column is used. The oil is __________ with an _____________ heater for _______. The vapor is ________ by a Liebig ________ and is _________ in a conical flask. Hot ________ rises up the ____________ column. It’s a long _____ to _____, and the _________ from the ________ source, the _______ it gets. Most of the vapor __________ on the glass _________ inside the ________ and drips back into the _________. Only the ______________ which are still ________ at the very ______ of the ________ enter the side arm and ________ to liquid. _________ uses the same _________ but on a mammoth scale in _______ fractional ___________ columns. The hot _____ enters near the _________ at a __________ 330 Celsius. The column becomes ________ towards the top. ___________ which remain as _________ at 85 Celsius go _______ to the top and are piped _______. Different ________ condense at different ____________ running off at __________ levels. Those with __________boiling points are __________ at the ______. Those with ________ boiling ______ run off near the __________. The _________ the molecules the ________ the boiling _______. __________ distillation ________ crude oil into ________ fractions each containing _________ of similar size.