Exactly what is in a Medicine? (WM)
In this document you will ﬁnd the following material to pay the new AS speciﬁcation together with your students. Notes for students and teachers Modified Chemical Suggestions 13. four part n Answers to problems pertaining to 13. some part n Revised activity WM3 Answers to queries for revised activity WM3 Revised check your notes Revised map from the unit two 3 6th 7 on the lookout for 10 10
© Harcourt Education Ltd 2005 Salters Advanced Chemistry These pages had been downloaded coming from www.heinemann.co.uk/science
Notes for students and teachers
Chemical Story lines
At the end of WM3 on-page 109: 1 . Instead of Chemical substance Ideas 13. 4 examine 13. four part w, which is available on the Heinemann website. installment payments on your Read Section 13. 5 in your Chemical substance Ideas book which works with naming and making esters.
1 . While doing Substance Ideas 13. 5 to become alarmed to cover polyesters (page 318) or ester hydrolysis (page 319). These kinds of will be protected in Designer Polymers (DP). As a result there is no need to do Challenges 4, 6 (parts d & e) or eight (parts g & e). 2 . Add Esters coming from salicylic acid solution (page 315). 3. Remember that the anhydride reactions in pages 318–319 do not need to always be learned. They can be to explain activity WM5. you: A preparation of acetylsalicylsaure.
A revised version of activity WM3 investigates the hormone balance of –OH groups. It can be available on the Heinemann internet site.
End of unit check
Question three or more part electronic is not suitable for the brand new speciﬁcation. (This work is actually covered inside the Polymer Revolution (PR). )
© Harcourt Education Ltd 2005 Salters Advanced Chemistry These pages have been completely downloaded from www.heinemann.co.uk/science
a couple of
THE –OH GROUP IN ALCOHOLS, PHENOLS AND STOMACH ACIDS, part m
The —OH group in alcohols, phenols and stomach acids, part m
The hydroxyl group, —OH, can occur in three diverse environments in organic elements: G placed on an alkane chain in alcohols, one example is CH CH –OH several 2 ethanol. Alcohols will be of 3 types, major, secondary and tertiary, according to the position with the OH group. You have already studied these in Section 13. 4, portion a. G
attached to a benzene ring in phenols, for example
(Although phenols appear similar to alcohols they act very in a different way. It is generally true that functional organizations behave in another way when attached with an perfumed ring coming from when they are placed on an alkyl group. ) G
within a carboxyl group in carboxylic acids, for example To CH3 C OH ethanoic acid
Pertaining to details on naming carboxylic stomach acids see
section 13. several.
In this section we will certainly compare the fact that —OH group behaves during these three different kinds of compounds.
The —OH group can respond with water like this: R—OH + WATER
R—O– + H3O+
where Ur stands for the group of atoms which makes up the rest of the molecule (see Section 12. 1). Water on its own does this to a very small extent in the effect H—OH & H2O
H—O– & H3O+
Therefore , at any one time a small number of normal water molecules contribute H+ ions to other water molecules: water behaves as a weakened acid (see Section eight. 1). An identical reaction occurs with ethanol, but to a lesser extent. The equilibrium is situated further left, and ethanol is a weaker acid than water. With phenol, the equilibrium is placed further to the right within water: phenol is more acidic than water. Carboxylic acids are actually more acidic, though nonetheless weak. The order of acid strength is ethanol < water < phenol < carboxylic acids It is the stability of the R—O– ion formed through the acid which in turn decides how strong the acid is, for example where the position of equilibrium lies. In case the negative charge on the oxygen can be shared with other atoms, the R—O– ion will be more stable and more of it will probably be made. Inside the R—O– ion derived from alcohols, no this kind of sharing is possible. However , in phenols in addition to carboxylic stomach acids the electrical charge gets spread out with a process referred to as delocalisation. This requires a spreading out of the bad particals over the...