Sunday, January 30, 2005

Acids and Oxides

Good work today in class - I'm looking specifically for understanding of the experiment's aim.

Explicitly the aim of today was to use a metal oxide and explain the reaction with an acid and from this to extrapolate to wider conclusions.

What I want to see in your conclusion is the following:

  1. What did you observe?
  2. What do you expect to see in the evaporating dish tomorrow?
  3. What reaction happened? How could you tell that a reaction had occured?
  4. What happens when acids are reacted with metal oxides? Take a look at P101 for more ideas on this.
  5. What type of salt is always produced when sulphuric acid is used in a neutralisation?

So I want you to comment on observations, explain them in equations if you can, and use your results to predict what will happen if similar experiments are carried out.

The worksheet you were given will give you some ideas on oxide reactions and are good practice.

If everything is as in the book, you should not have seen any bubbles coming off as no gas should have been produced. Some of you noticed some bubbles. Was there enough to call this fizzing? Would we say that gas is a major product here? If not where do we think it may have come from?

What could we have done better in this experiment? Rarely are experiments ever perfect.

Don't forget to write your own method

Thursday, January 27, 2005

Acids and Alkalis - revision from year 8

Some of the trouble you may encounter in year 9 can be easily avoided by revising your year 8 notes. Acids, bases and salts builds on the acids and alkalis unit from last year and is not really all that different, except for the more detailed description of ion disociation.

Just as a reminder, I have scanned and uploaded the notes for the year 8 module from the year 8 book and added the questions for year 8 chemistry from the CGP guide for you to download and print. It would be a good idea to do these questions (use your books if you wish) and read these notes if you are having any difficulty.

Remember you can always ask any questions by email.

Notes can be found by clicking the following links:

Year 8 book - acids and alkalis chapter and summary
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Year 8 - CGP Practice Questions
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Hope these come in useful. Download and save quickly before the copyright people get me!

Monday, January 24, 2005

Acids, bases and salts – What you should know by the end of this unit

8.1 The characteristic properties of acids and bases
– describe the characteristic properties of acids as reactions with metals, bases, carbonates and effect on litmus
- define acids and bases in terms of proton transfer, limited to aqueous solutions
- describe the meaning of weak and strong acids and bases

– describe the characteristic properties of bases as reactions with acids and with ammonium salts and effect on litmus
– describe neutrality and relative acidity and alkalinity in terms of pH (whole numbers only) measured using Universal Indicator paper
– describe and explain the importance of controlling acidity in soil
8.2 Types of oxides
– classify oxides as either acidic or basic, related to metallic and non-metallic character
– further classify other oxides as neutral or amphoteric
8.3 Preparation of salts
– describe the preparation, separation and purification of salts as examples of some of the techniques specified in section 2.2 (b) and the reactions specified in section 8.1
– describe the preparation of insoluble salts by precipitation
– suggest a method of making a given salt from suitable starting materials, given appropriate information