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#103121 HSN Notes for Higher Physics

Posted by appujal on 11 October 2010 - 02:07 PM in Physics

hey guys when will it be possible to upload other notes for physics? I would relly help if you upload them soon :)
thanks



#103120 2011 Timetable SQA

Posted by appujal on 11 October 2010 - 01:21 PM in Revision and Exams

http://www.sqa.org.u...metable2011.pdf

I am sitting my highers this year.
What about you guys?



#103119 PPA Hints

Posted by appujal on 10 October 2010 - 04:18 PM in Chemistry

View Postbred, on 05 May 2005 - 09:11 PM, said:

<u><b>PPA Answers</b></u>

<u><b>Unit 1</b></u>

<b>PPA1 - the effect of concentration changes on reaction rate</b>

Aim: The aim is to find the effect of varying the concentration of iodide ions on the rate of reaction between hydrogen peroxide and acidified potassium iodide solution.

a) Suggest a method for measuring the rate of this reaction

<b>Since the amount of thiosulphate ions initially present will be the same in each experiment, the appearance of the blue/black colour will always represent the same extent of reaction. So if t is the time it takes for the blue/black colour to appear then we can take 1/t as a measure of the reaction rate.</b>

b) The experiment was carried out to investigate the effect of iodide ion concentration on reaction rate. Suggest two factors which should be kept constant throughout the experiment.

<b>
1. The concentration of hydrogen peroxide
2. The temperature at which the experiments are performed.</b>

c) How is the course of reaction followed?

<b>The course of this reaction can be followed by carrying it out in the presence of small quantities of starch and sodium thiosulphate solutions.</b>

d) Suggest any safety precautions which should be carried out.

<b>
1. Safety glasses should be worn as both 1 mol l-1 sulphuric acid and 0. 1 mol l-1 hydrogen peroxide irritate the eyes.
2. Syringes should be pointed downwards to prevent inury.</b>

<b>PPA2 - the effect of temperature changes on reaction rate</b>

Aim: The aim is to find the effect of varying temperature on the rate of reaction between oxalic acid and an acidified solution of potassium permanganate.

a) Suggest an experiment to investigate the effect of temperature on the reaction rate - can you name the acid used?

<b>Oxalic acid.</b>

b) Suggest two factors which should be kept constant throughout the experiment.

<b>The concentrations and volumes of the reactants.</b>

c) How is the course of the reaction followed?

<b>Initially the reaction mixture is purple in colour due to the presence of the permanganate ions but it will turn colourless as soon as they are used up.</b>

d) What are the units of reaction rate?

<b>s-1</b>

e) Suggest any safety precautions which should be carried out.

<b>
1. Safety glasses should be worn as both 1 mol l-1 sulphuric acid and 0.1 mol l-1 hydrogen peroxide irritate the eyes.
2. Syringes should be pointed downwards to prevent inury.</b>

<b>PPA3 - The Enthalpy of Combustion</b>

Aim: The aim is to determine the enthalpy of combustion of ethanol.

a) Draw a diagram of the apparatus you would use

<img src='http://img.photobucket.com/albums/v664/bred2k5/ethanol.jpg' border='0' alt='user posted image' />

b) List all the safety precautions you should take

<b>
1. Safety glasses hould be worn.
2. Experiment apparatus should be kept well away from other flammable substances.</b>

c) The experimental value is often much less than the data book value. Give two reasons for this, including one which is not related to heat loss to the surroundings.

<b>
1. Heat was lost to the surroundings.
2. Incomplete combustion of ethanol.</b>

<b><u>Unit 2</u></b>

<b>PPA 1 - Oxidation</b>

Aim: The aim is to use the mild oxidising agents (acidified potassium dichromate solution, Benedict's solution and Tollen's reagent) to distinguish between two given carbonyl compounds, one of which is an aldehyde, the other a ketone.

a) Name suitable oxidising agents and be able to give the colour change involved when they react.

<b>
With aldehydes:
Tollen's reagent gives a silver mirror effect on the side of the test tube.
With Fehling's solution the blue colour transforms into a dark red precipitate of copper (I) oxide.
With ketones:
There is no change.</b>

b) Why is the potassium dichromate acidified?

<b>To increase the number of H+ ions</b>

c) List all the safety precautions you should take

<b>
1. Safety glasses should be worn
2. Gloves should be worn to handle Tollen's reagent and the carbonyl compounds.</b>

<b>PPA2 - making esters</b>

Aim: The aim is to prepare an ester and identify some of the characteristic properties of esters.

a) Describe the function of the sulphuric acid.

<b>Sulphuric acid performs as a strong oxidising agent.</b>

b) Draw a diagram to show how you would heat the mixture

<img src='http://img.photobucket.com/albums/v664/bred2k5/esters.jpg' border='0' alt='user posted image' />

c) Mention any necessary safety precautions

<b>Safety goggles should be worn.</b>

d) Describe how you would detect the presence of an ester

<b>
1. There should be an oily layer on the top of the reaction mixture if an ester is present.
2. The ester should also give off a pleasant smell, similar to that of fruits.</b>

e) It was stated that some of the reaction mixture would be lost through evaporation during heating. Make an addition to your diagram to show how this could be reduced.

<b>This is the wet paper towel wedge shown in the above diagram.</b>

<b>PPA3 - Factors affecting enzyme activity</b>

Aim: The aim is to investigate the effect of pH or temperature changes on enzyme activity.

a) Suggest a method for measuring enzyme activity of an enzyme under conditions of varied pH or temperature.

<b>
pH:
Addition of hydrogen peroxide to a test tube containing 3 potato discs. Record the number of bubbles of oxygen given off during a period of 3 minutes with a soluton of pH 7, another of pH 1, and another of pH 13.
Temperature:
Same as pH except the only solution used should be deionised water and 4 experiments should be carried out: one with the water at 30°C, another at 40°C, another at 50°C, and another at 60°C.</b>

b) What measurements would you take?

<b>
For both pH and temperature:
- Count and record the number of bubbles of oxygen produced during the first 3 minutes of the reaction
For temperature only:
Measure and record the steady temperature just before adding the hydrogen peroxide.</b>

c) What form would the resulting graph of pH/temperature against enzyme activity take?

<b>The form of a line graph.</b>

<b><u>Unit 3</u></b>

<b>PPA1 - Hess's Law</b>

Aim : The aim of the experiment is to confirm Hess's law.

a) What measurements must be taken at each stage?

<b>
1. The change in temperature
2. The mass of KOH
3. The mass of acid/water</b>

b) Explain why a plastic beaker is preferable to a metal one.

<b>Plastic performs better as a heat insulator than metal.</b>

c) List any safety precautions you would take.

<b>1. Safety goggles should be worn as the hydrochloric acid will irrate the eyes if contact is made
2. Care should also be taken with the potassium hydroxide as it is corrosive.</b>

d) Before adding together the solutions of acid and alkali, how is the initial temperature determined?

<b>The acid and alkali are each poured into a plastic beaker or polystyrene cup then their temperature is determined with the use of a thermometer.</b>

<b>PPA2 - Quantative Electrolysis</b>

Aim: The aim is to confirm the reaction 2H+(aq) + 2e ----> H2(g), that is to determine the quantity of electricity required to produce one mole of hydrogen by electrolysing dilute sulphuric acid.

a) Draw a diagram of the apparatus used.

<b>Basically, sketch the apparatus in this photo:</b>
<img src='http://www.labsupply.com.hk/images/Sci-ed%20chem%20electrolysis.jpg' border='0' alt='user posted image' />

b) In order to find the quantity of electricity in order to produce one mole of hydrogen by electrolysis, what measurements have to be made?

<b>96,500C is the charge associated with one mole of electrons.
The mass or volume of an element discharged can be calculated by the quantity of
electricity passed and vice-versa.</b>

c) List any safety precautions you would take.

<b>1. Safety glasses should be worn
2. An alternating current should be used to prevent electric shocks.</b>

<b>PPA3 - A Redox Titration</b>

Aim: The aim is to determine the mass of vitamin C in a tablet by carrying out a redox titration using a solution of iodine of accurately known concentration and starch solution as an indicator.

a) What is meant by a standard solution and how can one be prepared?

<b>A standard solution is a solution of known molarity. One can be prepard by adding some deionised water of a known volume to a vitamin C tablet in a beaker. Add a few drops of starch solution and then add iodine solution from a burette.</b>

b) How could the end point of the titration be determined?

<b>By the colour change from clear to blue/black.</b>

c) List an apparatus needed for such a titration.

<b>-small beaker
- wash bottle
- 250cm cubed standard flask
- filter funnel
- 25cm cubed pipette
- 50cm cubed burette
- conical flask
- pipette filter
- white tile
- standard solution of iodine
- starch solution
- vitamin C tablet
- deionised water</b>

d) From the results of several titrations, including a rough one, what volume of solution would be used in the calculation?

<b>75cm cubed.</b>

Thanks :)



#103118 HSN Notes for Higher Physics

Posted by appujal on 08 October 2010 - 06:12 PM in Physics

Could you possibly put course notes on for Electricity and Electronics? As Free

I was hoping I could use them ....because the maths ones really healped me (thanks!! :) )