hey guys here is a whole topic summary for a QA chemistry chemical analysis now in here on the different parts that you need to know if you want to check stuff off as we go along you can get that in a free version grab watching at my website or perhaps a pure substance is just gonna have one thing in it whether that is an element or one compound in it a mixture is gonna have lots of different things in it lots of different elements and lots different compounds compounds are going to be things that are
chemically bonded together mixtures are not chemically bonded together if you have a pure substance it is going to melt at its melting points if you have a mixture is grandparents over a range of melting points we can test this by getting some crystals of pure solution into a very very thin tube putting it into a rather old-fashioned tear melting point apparatus you can see that the ends are the very thin tube have the crystals in so we can see that happening and then they go in at the top of the melting point apparatus and as
the temperature rises this is slowly heated up we can have a look through a little glass window and see if the substance melts at one temperature or whether it melts slowly over a range of temperatures we can use chromatography to separate out compounds and you're going to get probably waited in classes beautiful beautiful and separations by phelp em we need to make sure that the end of paper is just in the water and that you've drawn your start line in pencil if you draw it in hairnet then you'll start really into one as well and
those gonna cause you problems we're gonna put a lid on here to stop the silver and evaporating when we once work out are a father you EDD students moved by the spot divided by the distance moved by the sulphate in an experiment when you see bubbles coming up something chance so it's going to be one of these four types of gases hydrogen gas okay gasps carbon dioxide or chlorine gas which test for hydrogen gas it is a squeaky pup oxygen gas is going to relight a glowing splint carbon dioxide turns cloudy and chlorine gas is
going to bleach I love flame tests they are so so pretty you need to know that lithium will burn with the crimson flame sodium or Burma the yellow flame casseon will burn with the line at frame calcium with red flame barium with the green flame you've known as an unlit green and copper is going to burn with a blue green flame if you're going to say to my dioxide chest feel positive ions we need to look at the oil equations and we need to look at the precipitates testing for aluminium of sodium hydroxide is going
to give you a white precipitate which is then going to dissolve testing for calcium with sodium hydroxide is just going to give you a white precipitate which will not solve testing for magnesium reseda hydroxide will give you a white precipitate so in this circumstance you would need another test to differentiate between calcium and magnesium copper ions will give you a light blue precipitate iron two ions will give you a gray green 6 8 and 9 3 ions will give you an orange precipitates for the ionic equations we have our hydroxide iron and then our metal
ions and you are expected to know all of these then you just need to make sure your number of negative hydroxyl ions equals the number of positive ions so aluminum is three positive so it needs the wee negative ions to become a neutral overall calcium is two positive so it needs two negative ions to become neutral overall magnesium of h2 calcium o h2 iron o h 2i n 3o h3 if you want to test for halide ions you can add silver nitrate and chloride ions will give a white precipitate bright red eyes will give cream
sift a and iodide ions will give a yellow precipitate yellow but not as yellow as the walls my lab used to be now this can sometimes be very very such a difference in the best way to do it is by comparing it with the other things if you want to test something for a carbonate iron you need to add hydrochloric acid set up a delivery tube so any gas evolved would be collected down into lime water and if his carbon dioxide the Lima Walker cloudy if you want to test a sample sip it and then
Sophia and she need to add her to correct acid in it add barium chloride and if it contains so far ions you will get a white precipitate formed in some cases during testing class might not be as good as using an instrumental method instrumental methods can be faster they can be more accurate and they're unbiased [Music]
