Database Systems Assignment Example | Topics and Well Written Essays - 250 words

Database Systems - Assignment Example A distributed request refers data from several different data processor sites. Each request can access data from many sites where a transaction access several data sites. Similar to requests, transactions can also be categorised as remote and distributed. A remote transaction is composed with several requests but accesses data in a single data processor site. A distributed transaction allows referring several local and remote data processor sites where an individual request can refer data in single location but the entire transaction will refer several sites to complete the transaction. Question 2 Most of these problems occur due to data transformation incompatibilities and conventions used. With in the different divisions of an organization, operational data may vary in terms of how they are recorded or on the data type and structures used. For an example if we take a sales company the Customer service division may use ‘pending’,’ active’, ‘inactiveà ¢â‚¬â„¢ and ‘cancelled’ but Audit division may use number tags such as 1, 2, 3, and 4. For same two divisions they may use different conventions for entering customer phone number to the database. For an instance where the phone number can be entered as 091-3453489 by Audit division and the Customer services division enters it as 0913453489.

Enthalpy of Neutralisation Lab Report Example | Topics and Well Written Essays - 500 words

Enthalpy of Neutralisation - Lab Report Example As a matter of fact, this variation is attributed to the fact that when a strong acid is used, full ionization takes place while with a weak acid; ionization is incomplete (Jarvis, 2011). In this experiment, NaOH is mixed with HCL and later with CH3COOH. Place 500 mL of water into the calorimeter and add 150 mL of 1.0 M sodium hydroxide. Measure 160 mL (an excess) of 1.0 M hydrochloric acid into a 400 mL beaker. Start the stopwatch and stir the two solutions with separate stirring rods and measure their temperatures (use separate thermometers) at 30 s intervals as above. (DO NOT stir the solutions with the thermometers.) After 5 min (do not reset timer to zero) rapidly, but quantitatively, pour the HCl into the calorimeter. Replace the stopper. Continue stirring and record the temperature of the reaction mixture at 30 s intervals for the next 5 min. After the experiment is completed, test the solution with two drops of phenolphthalein. If the reaction mixture is alkaline, insufficient acid has been added and the results are worthless † start again. The first part of the experiment is about reactions between fully ionized strong acids and strong bases and the sole real chemical change is formation of water molecule from hydrogen ions and hydroxide ions. This is given as follows, Evidently, the reaction between NaOH and HCL yields a higher enthalpy of neutralization as compared to the reaction between NaOH and CH3COOH. This is attributed to the fact that the enthalpy of neutralization of a NaOH with a HCL involves complete ionization of the dilute aqueous solutions and hence the reaction involves higher energy. In the case of CH3COOH, while NaOH undergoes complete ionization, CH3COOH only partly ionizes and as a result the enthalpy of neutralization is lower. There are various methods used in measurement of such heat. Initially measurements were premised on simple thermometric